U.S. patent application number 11/318334 was filed with the patent office on 2006-08-31 for tissue penetration device.
Invention is credited to Don Alden, Dirk Boecker, Barry Dean Briggs, Dominique Freeman, Ray Freeman, George Gogue, Jon Hewitt Leonard.
Application Number | 20060195133 11/318334 |
Document ID | / |
Family ID | 40707672 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060195133 |
Kind Code |
A1 |
Freeman; Dominique ; et
al. |
August 31, 2006 |
Tissue penetration device
Abstract
A tissue penetration device includes a magnetic source that
produces a controllable magnetic field in a magnetically active
region adjacent the magnetic source. A magnetic member is disposed
at least partially in the magnetically active region. A permanent
magnet is disposed at a proximal end of the magnetically active
region for zeroing the position of the magnetic member while the
tissue penetration device is inactive.
Inventors: |
Freeman; Dominique; (La
Hondo, CA) ; Boecker; Dirk; (Palo Allo, CA) ;
Alden; Don; (Sunnyvale, CA) ; Briggs; Barry Dean;
(Campbell, CA) ; Leonard; Jon Hewitt; (Sunnyvale,
CA) ; Freeman; Ray; (Cambridge, GB) ; Gogue;
George; (Beaverton, OR) |
Correspondence
Address: |
HELLER EHRMAN LLP
275 MIDDLEFIELD ROAD
MENLO PARK
CA
94025-3506
US
|
Family ID: |
40707672 |
Appl. No.: |
11/318334 |
Filed: |
December 22, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10127395 |
Apr 19, 2002 |
7025774 |
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11318334 |
Dec 22, 2005 |
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60298055 |
Jun 12, 2001 |
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60298126 |
Jun 12, 2001 |
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60297861 |
Jun 12, 2001 |
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60298001 |
Jun 12, 2001 |
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60298056 |
Jun 12, 2001 |
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60297864 |
Jun 12, 2001 |
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60297860 |
Jun 12, 2001 |
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Current U.S.
Class: |
606/181 |
Current CPC
Class: |
A61B 5/150175 20130101;
A61B 5/15123 20130101; B01L 2200/10 20130101; A61M 2005/004
20130101; A61B 5/150099 20130101; A61B 5/15186 20130101; A61B
17/32093 20130101; A61B 5/15176 20130101; A61B 5/15146 20130101;
A61B 5/15019 20130101; A61B 5/150221 20130101; B01L 3/502715
20130101; A61B 5/15117 20130101; A61B 5/15171 20130101; G01N
33/4905 20130101; B01L 2300/18 20130101; A61B 5/157 20130101; A61B
5/150167 20130101; A61B 5/150427 20130101; A61B 5/15113 20130101;
A61B 5/15151 20130101; A61B 5/15153 20130101; A61B 5/15169
20130101; G01N 33/557 20130101; A61B 5/150061 20130101; A61B
5/14532 20130101; A61B 5/150358 20130101; A61B 5/150068 20130101;
A61B 5/150503 20130101; A61B 5/150572 20130101; A61B 5/150152
20130101; B01L 3/5027 20130101; A61B 5/150213 20130101; A61B
5/15184 20130101; B01L 3/50273 20130101; B01L 3/502746 20130101;
B01L 2300/0663 20130101; A61M 5/158 20130101; A61B 5/150022
20130101; A61B 5/15163 20130101; A61M 5/46 20130101; A61B 5/15178
20130101 |
Class at
Publication: |
606/181 |
International
Class: |
A61B 17/32 20060101
A61B017/32 |
Claims
1. A tissue penetration device, comprising: a) a magnetic source
that produces a controllable magnetic field in a magnetically
active region adjacent the magnetic source; b) a magnetic member
disposed at least partially in the magnetically active region; c) a
permanent magnet disposed at a proximal end of the magnetically
active region for zeroing the position of the magnetic member while
the tissue penetration device is inactive.
2. The tissue penetration device of claim 1, wherein the permanent
magnet comprises a bar magnet.
3. The tissue penetration device of claim 1, wherein the magnetic
source comprises at least one coiled electrical conductor and the
permanent magnet comprises a cylindrical magnet having an aperture
disposed about the proximal end of the magnetically active
region.
4. The tissue penetration device of claim 3, wherein the permanent
magnet is spaced proximally from a proximal end of the at least one
coiled electrical conductor.
5. A controllable electromagnetic driver for driving a lancet and
obtaining a sample of blood from a patient, comprising: a) a driver
coil pack having a proximal end and a distal end comprising a
plurality of adjacent electric coils with each coil being comprised
of an electrical conductor wound about an axial lumen of each coil
with the axial lumens of the coils in a coaxial configuration; b)
an elongate coupler shaft having a proximal end and a distal end
disposed within an axial lumen of the driver coil pack; c) a
magnetic member secured to a distal portion of the elongate coupler
shaft and configured to slide axially within the axial lumen of the
driver coil pack; d) a position sensor disposed at adjacent the
driver coil pack, comprising an optical reader and an optical flag
secured to a proximal section of the coupler shaft with the optical
flag configured to slide axially adjacent the optical reader and to
measure the position of the coupler shaft relative to the position
sensor and driver coil pack; e) a processor which is electrically
coupled to the electrical conductors of the plurality of adjacent
electric coils and position sensor and which is configured to
control a magnitude of a magnetic field in the axial lumen of the
driver coil pack by controlling the amount of electrical current
flowing through the electrical conductor of each coil based on
closed loop feedback position data from the position sensor; and f)
a lancet coupler secured to the distal end of the coupler shaft and
configured to be coupled to a lancet.
6. A flat coil tissue penetration device, comprising: a) a magnetic
source that produces a first magnetic field in a first magnetically
active region and a second magnetic field in a second magnetically
active region; b) a flat coil secured to a translation substrate
and having a leading segment disposed at least partially within the
first magnetically active region and. a trailing segment disposed
at least partially within the second magnetically active region;
and c) a sharpened member configured to penetrate tissue and
mechanically coupled to the translation substrate.
7. The tissue penetration device of claim 5, wherein the
translation substrate is configured to pivot about an axis.
8. The tissue penetration device of claim 5, wherein the
translation substrate is configured to move linearly.
9. The flat coil tissue penetration device of claim 5, further
comprising a feedback loop having processor which is electrically
coupled to elongate electrical conductors of the flat coil and
configured to control the magnitude of the force on the translation
substrate based on feedback from a position sensor that provides
position data of the translation substrate to the processor.
10. The tissue penetration device of claim 9, wherein the processor
is configured to control the magnetic force on the translation
substrate so as to have the translation substrate and tissue
sharpened member follow a predetermined tissue penetration profile.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No. 10/127,395
filed Apr. 19, 2002, which claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/298,055 filed Jun. 12, 2001; U.S.
Provisional Patent Application Ser. No. 60/298,126 filed Jun. 12,
2001; U.S. Provisional Patent Application Ser. No. 60/297,861 filed
Jun. 12, 2001; U.S. Provisional Patent Application Ser. No.
60/298,001 filed Jun. 12, 2001, U.S. Provisional Patent Application
Ser. No. 60/298,056 filed Jun. 12, 2001; U.S. Provisional Patent
Application Ser. No. 60/297,864 filed Jun. 12, 2001; and U.S.
Provisional Patent Application Ser. No. 60/297,860 filed Jun. 12,
2001; all U.S. patent applications stated above being hereby
incorporated by reference.
[0002] This application is also related to copending U.S. patent
application Ser. No. 10/127,201 filed Apr. 19, 2002 and U.S. Patent
Application Ser. No. 60/374,304 filed Apr. 19, 2002, both of which
are hereby incorporated by reference in their entirety.
BACKGROUND
[0003] Lancing devices are known in the medical health-care
products industry for piercing the skin to produce blood for
analysis. Biochemical analysis of blood samples is a diagnostic
tool for determining clinical information. Many point-of-care tests
are performed using whole blood, the most common being monitoring
diabetic blood glucose level. Other uses for this method include
the analysis of oxygen and coagulation based on Prothrombin time
measurement. Typically, a drop of blood for this type of analysis
is obtained by making a small incision in the fingertip, creating a
small wound, which generates a small blood droplet on the surface
of the skin.
[0004] Early methods of lancing included piercing or slicing the
skin with a needle or razor. Current methods utilize lancing
devices that contain a multitude of spring, cam and mass actuators
to drive the lancet. These include cantilever springs, diaphragms,
coil springs, as well as gravity plumbs used to drive the lancet.
Typically, the device is pre-cocked or the user cocks the device.
The device is held against the skin and the user, or pressure from
the users skin, mechanically triggers the ballistic launch of the
lancet. The forward movement and depth of skin penetration of the
lancet is determined by a mechanical stop and/or dampening, as well
as a spring or cam to retract the lancet. Such devices have the
possibility of multiple strikes due to recoil, in addition to
vibratory stimulation of the skin as the driver impacts the end of
the launcher stop, and only allow for rough control for skin
thickness variation. Different skin thickness may yield different
results in terms of pain perception, blood yield and success rate
of obtaining blood between different users of the lancing
device.
[0005] Success rate generally encompasses the probability of
producing a blood sample with one lancing action, which is
sufficient in volume to perform the desired analytical test. The
blood may appear spontaneously at the surface of the skin, or may
be "milked" from the wound. Milking generally involves pressing the
side of the digit, or in proximity of the wound to express the
blood to the surface. The blood droplet produced by the lancing
action must reach the surface of the skin to be viable for testing.
For a one-step lance and blood sample acquisition method,
spontaneous blood droplet formation is requisite. Then it is
possible to interface the test strip with the lancing process for
metabolite testing.
[0006] When using existing methods, blood often flows from the cut
blood vessels but is then trapped below the surface of the skin,
forming a hematoma. In other instances, a wound is created, but no
blood flows from the wound. In either case, the lancing process
cannot be combined with the sample acquisition and testing step.
Spontaneous blood droplet generation with current mechanical
launching system varies between launcher types but on average it is
about 50% of lancet strikes, which would be spontaneous. Otherwise
milking is required to yield blood. Mechanical launchers are
unlikely to provide the means for integrated sample acquisition and
testing if one out of every two strikes does not yield a
spontaneous blood sample.
[0007] Many diabetic patients (insulin dependent) are required to
self-test for blood glucose levels five to six times daily.
Reducing the number of steps required for testing would increase
compliance with testing regimes. A one-step testing procedure where
test strips are integrated with lancing and sample generation would
achieve a simplified testing regimen. Improved compliance is
directly correlated with long-term management of the complications
arising from diabetes including retinopathies, neuropathies, renal
failure and peripheral vascular degeneration resulting from large
variations in glucose levels in the blood. Tight control of plasma
glucose through frequent testing is therefore mandatory for disease
management.
[0008] Another problem frequently encountered by patients who must
use lancing equipment to obtain and analyze blood samples is the
amount of manual dexterity and hand-eye coordination required to
properly operate the lancing and sample testing equipment due to
retinopathies and neuropathies particularly, severe in elderly
diabetic patients. For those patients, operating existing lancet
and sample testing equipment can be a challenge. Once a blood
droplet is created, that droplet must then be guided into a
receiving channel of a small test strip or the like. If the sample
placement on the strip is unsuccessful, repetition of the entire
procedure including re-lancing the skin to obtain a new blood
droplet is necessary.
[0009] What is needed is a device, which can reliably, repeatedly
and painlessly generate spontaneous blood samples. In addition, a
method for performing analytical testing on a sample that does not
require a high degree of manual dexterity or hand-eye coordination
is required. Integrating sample generation (lancing) with sample
testing (sample to test strip) will result in a simple one-step
testing procedure resulting in better disease management through
increased compliance with self testing regimes.
SUMMARY
[0010] Advantages can be achieved by use of a tissue penetration
device that has user definable control of parameters such as lancet
displacement, velocity of incision, retraction, acceleration, and
tissue dwell time. A device having features of the invention can
compensate for long-term changes in skin physiology, nerve
function, and peripheral vascular perfusion such as occurs in
diabetes, as well as diurnal variation in skin tensile properties.
Alternatively, a device having features of the invention can
compensate for skin differences between widely differing
populations such as pediatric and geriatric patients, in addition
to reducing the pain associated with lancing.
[0011] In one embodiment of the present invention, a tissue
penetration device includes a magnetic source that produces a
controllable magnetic field in a magnetically active region
adjacent the magnetic source. A magnetic member is disposed at
least partially in the magnetically active region. A permanent
magnet is disposed at a proximal end of the magnetically active
region for zeroing the position of the magnetic member while the
tissue penetration device is inactive.
[0012] In another embodiment of the present invention, a
controllable electromagnetic driver for driving a lancet and
obtaining a sample of blood from a patient is provided. A driver
coil pack has a proximal end and a distal end with a plurality of
adjacent electric coils. Each has an electrical conductor wound
about an axial lumen of each coil with the axial lumens of the
coils being in a coaxial configuration. An elongate coupler shaft
has a proximal end and a distal end disposed within an axial lumen
of the driver coil pack. A magnetic member is secured to a distal
portion of the elongate coupler shaft and is configured to slide
axially within the axial lumen of the driver coil pack. A position
sensor is disposed adjacent to the driver coil pack. The position
sensor is an optical reader and an optical flag secured to a
proximal section of the coupler shaft. The optical flag is
configured to slide axially adjacent the optical reader and measure
the position of the coupler shaft relative to the position sensor
and driver coil pack. A processor is electrically coupled to the
electrical conductors of the plurality of adjacent electric coils
and position sensor. The processor is configured to control a
magnitude of a magnetic field in the axial lumen of the driver coil
pack by controlling the amount of electrical current flowing
through the electrical conductor of each coil based on closed loop
feedback position data from the position sensor. A lancet coupler
is secured to the distal end of the coupler shaft and is configured
to be coupled to a lancet.
[0013] In another embodiment of the present invention, a flat coil
tissue penetration device is provided. A magnetic source produces a
first magnetic field in a first magnetically active region and a
second magnetic field in a second magnetically active region. A
flat coil is secured to a translation substrate and has a leading
segment disposed at least partially within the first magnetically
active region, and a trailing segment disposed at least partially
within the second magnetically active region. A sharpened member is
configured to penetrate tissue and is mechanically coupled to the
translation substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1-3 are graphs of lancet velocity versus position for
embodiments of spring driven, cam driven, and controllable force
drivers.
[0015] FIG. 4 illustrates an embodiment of a controllable force
driver in the form of a flat electric lancet driver that has a
solenoid-type configuration.
[0016] FIG. 5 illustrates an embodiment of a controllable force
driver in the form of a cylindrical electric lancet driver using a
coiled solenoid-type configuration.
[0017] FIG. 6 illustrates a displacement over time profile of a
lancet driven by a harmonic spring/mass system.
[0018] FIG. 7 illustrates the velocity over time profile of a
lancet driver by a harmonic spring/mass system.
[0019] FIG. 8 illustrates a displacement over time profile of an
embodiment of a controllable force driver.
[0020] FIG. 9 illustrates a velocity over time profile of an
embodiment of a controllable force driver.
[0021] FIG. 10 illustrates the lancet needle partially retracted,
after severing blood vessels; blood is shown following the needle
in the wound tract.
[0022] FIG. 11 illustrates blood following the lancet needle to the
skin surface, maintaining an open wound tract.
[0023] FIG. 12 is a diagrammatic view illustrating a controlled
feed-back loop.
[0024] FIG. 13 is a graph of force vs. time during the advancement
and retraction of a lancet showing some characteristic phases of a
lancing cycle.
[0025] FIG. 14 illustrates a lancet tip showing features, which can
affect lancing pain, blood volume, and success rate.
[0026] FIG. 15 illustrates an embodiment of a lancet tip.
[0027] FIG. 16 is a graph showing displacement of a lancet over
time.
[0028] FIG. 17 is a graph showing an embodiment of a velocity
profile, which includes the velocity of a lancet over time
including reduced velocity during retraction of the lancet.
[0029] FIG. 18 illustrates the tip of an embodiment of a lancet
before, during and after the creation of an incision braced with a
helix.
[0030] FIG. 19 illustrates a finger wound tract braced with an
elastomer embodiment.
[0031] FIG. 20 is a perspective view of a tissue penetration device
having features of the invention.
[0032] FIG. 21 is an elevation view in partial longitudinal section
of the tissue penetration device of FIG. 20.
[0033] FIG. 22 is an elevation view in partial section of an
alternative embodiment.
[0034] FIG. 23 is a transverse cross sectional view of the tissue
penetration device of FIG. 21 taken along lines 23-23 of FIG.
21.
[0035] FIG. 24 is a transverse cross sectional view of the tissue
penetration device of FIG. 21 taken along lines 24-24 of FIG.
21.
[0036] FIG. 25 is a transverse cross sectional view of the tissue
penetration device of FIG. 21 taken along lines 25-25 of FIG.
21.
[0037] FIG. 26 is a transverse cross sectional view of the tissue
penetration device of FIG. 21 taken along lines 26-26 of FIG.
21.
[0038] FIG. 27 is a side view of the drive coupler of the tissue
penetration device of FIG. 21.
[0039] FIG. 28 is a front view of the drive coupler of the tissue
penetration device of FIG. 21 with the lancet not shown for
purposes of illustration.
[0040] FIGS. 29A-29C show a flowchart illustrating a lancet control
method.
[0041] FIG. 30 is a diagrammatic view of a patient's finger and a
lancet tip moving toward the skin of the finger.
[0042] FIG. 31 is a diagrammatic view of a patient's finger and the
lancet tip making contact with the skin of a patient's finger.
[0043] FIG. 32 is a diagrammatic view of the lancet tip depressing
the skin of a patient's finger.
[0044] FIG. 33 is a diagrammatic view of the lancet tip further
depressing the skin of a patient's finger.
[0045] FIG. 34 is a diagrammatic view of the lancet tip penetrating
the skin of a patient's finger.
[0046] FIG. 35 is a diagrammatic view of the lancet tip penetrating
the skin of a patient's finger to a desired depth.
[0047] FIG. 36 is a diagrammatic view of the lancet tip withdrawing
from the skin of a patient's finger.
[0048] FIGS. 37-41 illustrate a method of tissue penetration that
may measure elastic recoil of the skin.
[0049] FIG. 42 is a graphical representation of position and
velocity vs. time for a lancing cycle.
[0050] FIG. 43 illustrates a sectional view of the layers of skin
with a lancet disposed therein.
[0051] FIG. 44 is a graphical representation of velocity vs.
position of a lancing cycle.
[0052] FIG. 45 is a graphical representation of velocity vs. time
of a lancing cycle.
[0053] FIG. 46 is an elevation view in partial longitudinal section
of an alternative embodiment of a driver coil pack and position
sensor.
[0054] FIG. 47 is a perspective view of a flat coil driver having
features of the invention.
[0055] FIG. 48 is an exploded view of the flat coil driver of FIG.
47.
[0056] FIG. 49 is an elevational view in partial longitudinal
section of a tapered driver coil pack having features of the
invention.
[0057] FIG. 50 is a transverse cross sectional view of the tapered
coil driver pack of FIG. 49 taken along lines 50-50 in FIG. 49.
[0058] FIG. 51 shows an embodiment of a sampling module which
houses a lancet and sample reservoir.
[0059] FIG. 52 shows a housing that includes a driver and a chamber
where the module shown in FIG. 51 can be loaded.
[0060] FIG. 53 shows a tissue penetrating sampling device with the
module loaded into the housing.
[0061] FIG. 54 shows an alternate embodiment of a lancet
configuration.
[0062] FIG. 55 illustrates an embodiment of a sample input port,
sample reservoir and ergonomically contoured finger contact
area.
[0063] FIG. 56 illustrates the tissue penetration sampling device
during a lancing event.
[0064] FIG. 57 illustrates a thermal sample sensor having a sample
detection element near a surface over which a fluid may flow and an
alternative position for a sampled detection element that would be
exposed to a fluid flowing across the surface.
[0065] FIG. 58 shows a configuration of a thermal sample sensor
with a sample detection element that includes a separate heating
element.
[0066] FIG. 59 depicts three thermal sample detectors such as that
shown in FIG. 58 with sample detection elements located near each
other alongside a surface.
[0067] FIG. 60 illustrates thermal sample sensors positioned
relative to a channel having an analysis site.
[0068] FIG. 61 shows thermal sample sensors with sample detection
analyzers positioned relative to analysis sites arranged in an
array on a surface.
[0069] FIG. 62 schematically illustrates a sampling module device
including several possible configurations of thermal sample sensors
including sample detection elements positioned relative to sample
flow channels and analytical regions.
[0070] FIG. 63 illustrates a tissue penetration sampling device
having features of the invention.
[0071] FIG. 64 is a top view in partial section of a sampling
module of the tissue penetration sampling device of FIG. 63.
[0072] FIG. 65 is a cross sectional view through line 65-65 of the
sampling module shown in FIG. 64.
[0073] FIG. 66 schematically depicts a sectional view of an
alternative embodiment of the sampling module.
[0074] FIG. 67 depicts a portion of the sampling module surrounding
a sampling port.
[0075] FIGS. 68-70 show in sectional view one implementation of a
spring powered lancet driver in three different positions during
use of the lancet driver.
[0076] FIG. 71 illustrates an embodiment of a tissue penetration
sampling device having features of the invention.
[0077] FIG. 72 shows a top surface of a cartridge that includes
multiple sampling modules.
[0078] FIG. 73 shows in partial section a sampling module of the
sampling cartridge positioned in a reader device.
[0079] FIG. 74 is a perspective view in partial section of a tissue
penetration sampling device with a cartridge of sampling
modules.
[0080] FIG. 75 is a front view in partial section of the tissue
penetration sampling device of FIG. 56.
[0081] FIG. 76 is a top view of the tissue penetration sampling
device of FIG. 75.
[0082] FIG. 77 is a perspective view of a section of a sampling
module belt having a plurality of sampling modules connected in
series by a sheet of flexible polymer.
[0083] FIG. 78 is a perspective view of a single sampling module of
the sampling module belt of FIG. 59.
[0084] FIG. 79 is a bottom view of a section of the flexible
polymer sheet of the sampling module of FIG. 78 illustrating the
flexible conductors and contact points deposited on the bottom
surface of the flexible polymer sheet.
[0085] FIG. 80 is a perspective view of the body portion of the
sampling module of FIG. 77 without the flexible polymer cover sheet
or lancet.
[0086] FIG. 81 is an enlarged portion of the body portion of the
sampling module of FIG. 80 illustrating the input port, sample flow
channel, analytical region, lancet channel and lancet guides of the
sampling module.
[0087] FIG. 82 is an enlarged elevational view of a portion of an
alternative embodiment of a sampling module having a plurality of
small volume analytical regions.
[0088] FIG. 83 is a perspective view of a body portion of a lancet
module that can house and guide a lancet without sampling or
analytical functions.
[0089] FIG. 84 is an elevational view of a drive coupler having a
T-slot configured to accept a drive head of a lancet.
[0090] FIG. 85 is an elevational view of the drive coupler of FIG.
84 from the side and illustrating the guide ramps of the drive
coupler.
[0091] FIG. 86 is a perspective view of the drive coupler of FIG.
84 with a lancet being loaded into the T-slot of the drive
coupler.
[0092] FIG. 87 is a perspective view of the drive coupler of FIG.
86 with the drive head of the lancet completely loaded into the
T-slot of the drive coupler.
[0093] FIG. 88 is a perspective view of a sampling module belt
disposed within the T-slot of the drive coupler with a drive head
of a lancet of one of the sampling modules loaded within the T-slot
of the drive coupler.
[0094] FIG. 89 is a perspective view of a sampling module cartridge
with the sampling modules arranged in a ring configuration.
[0095] FIG. 90 is a perspective view of a sampling module cartridge
with the plurality of sampling modules arranged in a block matrix
with lancet drive heads configured to mate with a drive coupler
having adhesive coupling.
[0096] FIG. 91 is a side view of an alternative embodiment of a
drive coupler having a lateral slot configured to accept the
L-shaped drive head of the lancet that is disposed within a lancet
module and shown with the L-shaped drive head loaded in the lateral
slot.
[0097] FIG. 92 is an exploded view of the drive coupler, lancet
with L-shaped drive head and lancet module of FIG. 91.
[0098] FIG. 93 is a perspective view of the front of a lancet
cartridge coupled to the distal end of a controlled electromagnetic
driver.
[0099] FIG. 94 is an elevational front view of the lancet cartridge
of FIG. 93.
[0100] FIG. 95 is a top view of the lancet cartridge of FIG.
93.
[0101] FIG. 96 is a perspective view of the lancet cartridge of
FIG. 93 with a portion of the cartridge body and lancet receptacle
not shown for purposes of illustration of the internal
mechanism.
[0102] FIGS. 97-101 illustrate an embodiment of an agent injection
device.
[0103] FIGS. 102-106 illustrate an embodiment of a cartridge for
use in sampling having a sampling cartridge body and a lancet
cartridge body.
DETAILED DESCRIPTION
[0104] Variations in skin thickness including the stratum corneum
and hydration of the epidermis can yield different results between
different users with existing tissue penetration devices, such as
lancing devices wherein the tissue penetrating element of the
tissue penetration device is a lancet. Many current devices rely on
adjustable mechanical stops or damping, to control the lancet's
depth of penetration.
[0105] Displacement velocity profiles for both spring driven and
cam driven tissue penetration devices are shown in FIGS. 1 and 2,
respectively. Velocity is plotted against displacement X of the
lancet. FIG. 1 represents a displacement/velocity profile typical
of spring driven devices. The lancet exit velocity increases until
the lancet hits the surface of the skin 10. Because of the tensile
characteristics of the skin, it will bend or deform until the
lancet tip cuts the surface 20, the lancet will then penetrate the
skin until it reaches a full stop 30. At this point displacement is
maximal and reaches a limit of penetration and the lancet stops.
Mechanical stops absorb excess energy from the driver and transfer
it to the lancet. The energy stored in the spring can cause recoil
resulting in multiple piercing as seen by the coiled profile in
FIG. 1. This results in unnecessary pain from the additional tissue
penetration as well as from transferring vibratory energy into the
skin and exciting nerve endings. Retraction of the lancet then
occurs and the lancet exits the skin 40 to return into the housing.
Velocity cannot be controlled in any meaningful way for this type
of spring-powered driver.
[0106] FIG. 2 shows a displacement/velocity profile for a cam
driven driver, which is similar to that of FIG. 1, but because the
return path is specified in the cam configuration, there is no
possibility of multiple tissue penetrations from one actuation. Cam
based drivers can offer some level of control of lancet velocity
vs. displacement, but not enough to achieve many desirable
displacement/velocity profiles.
[0107] Advantages are achieved by utilizing a controllable force
driver to drive a lancet, such as a driver, powered by
electromagnetic energy. A controllable driver can achieve a desired
velocity versus position profile, such as that shown in FIG. 3.
Embodiments of the present invention allow for the ability to
accurately control depth of penetration, to control lancet
penetration and withdrawal velocity, and therefore reduce the pain
perceived when cutting into the skin. Embodiments of the invention
include a controllable driver that can be used with a feedback loop
with a position sensor to control the power delivered to the
lancet, which can optimize the velocity and displacement profile to
compensate for variations in skin thickness
[0108] Pain reduction can be achieved by using a rapid lancet
cutting speed, which is facilitated by the use of a lightweight
lancet. The rapid cutting minimizes the shock waves produced when
the lancet strikes the skin in addition to compressing the skin for
efficient cutting. If a controllable driver is used, the need for a
mechanical stop can be eliminated. Due to the very light mass of
the lancet and lack of a mechanical stop, there is little or no
vibrational energy transferred to the finger during cutting.
[0109] The lancing devices such as those whose velocity versus
position profiles are shown in FIGS. 1 and 2 typically yield 50%
spontaneous blood. In addition, some lancing events are
unsuccessful and yield no blood, even on milking the finger. A
spontaneous blood droplet generation is dependent on reaching the
blood capillaries and venuoles, which yield the blood sample. It is
therefore an issue of correct depth of penetration of the cutting
device. Due to variations in skin thickness and hydration, some
types of skin will deform more before cutting starts, and hence the
actual depth of penetration will be less, resulting in less
capillaries and venuoles cut. A controllable force driver can
control the depth of penetration of a lancet and hence improve the
spontaneity of blood yield. Furthermore, the use of a controllable
force driver can allow for slow retraction of the lancet (slower
than the cutting velocity) resulting in improved success rate due
to the would channel remaining open for the free passage of blood
to the surface of the skin.
[0110] Spontaneous blood yield occurs when blood from the cut
vessels flow up the wound tract to the surface of the skin, where
it can be collected and tested. Tissue elasticity parameters may
force the wound tract to close behind the retracting lancet
preventing the blood from reaching the surface. If however, the
lancet were to be withdrawn slowly from the wound tract, thus
keeping the wound open, blood could flow up the patent channel
behind the tip of the lancet as it is being withdrawn (ref. FIGS.
10 and 11). Hence the ability to control the lancet speed into and
out of the wound allows the device to compensate for changes in
skin thickness and variations in skin hydration and thereby
achieves spontaneous blood yield with maximum success rate while
minimizing pain.
[0111] An electromagnetic driver can be coupled directly to the
lancet minimizing the mass of the lancet and allowing the driver to
bring the lancet to a stop at a predetermined depth without the use
of a mechanical stop. Alternatively, if a mechanical stop is
required for positive positioning, the energy transferred to the
stop can be minimized. The electromagnetic driver allows
programmable control over the velocity vs. position profile of the
entire lancing process including timing the start of the lancet,
tracking the lancet position, measuring the lancet velocity,
controlling the distal stop acceleration, and controlling the skin
penetration depth.
[0112] Referring to FIG. 4, an embodiment of a tissue penetration
device is shown. The tissue penetration device includes a
controllable force driver in the form of an electromagnetic driver,
which can be used to drive a lancet. The term Lancet, as used
herein, generally includes any sharp or blunt member, preferably
having a relatively low mass, used to puncture the skin for the
purpose of cutting blood vessels and allowing blood to flow to the
surface of the skin. The term Electromagnetic driver, as used
herein, generally includes any device that moves or drives a tissue
penetrating element, such as a lancet under an electrically or
magnetically induced force. FIG. 4 is a partially exploded view of
an embodiment of an electromagnetic driver. The top half of the
driver is shown assembled. The bottom half of the driver is shown
exploded for illustrative purposes.
[0113] FIG. 4 shows the inner insulating housing 22 separated from
the stationary housing or PC board 20, and the lancet 24 and flag
26 assembly separated from the inner insulating housing 22 for
illustrative purposes. In addition, only four rivets 18 are shown
as attached to the inner insulating housing 22 and separated from
the PC board 20. In an embodiment, each coil drive field core in
the PC board located in the PC Board 20 and 30 is connected to the
inner insulating housing 22 and 32 with rivets.
[0114] The electromagnetic driver has a moving part comprising a
lancet assembly with a lancet 24 and a magnetically permeable flag
26 attached at the proximal or drive end and a stationary part
comprising a stationary housing assembly with electric field coils
arranged so that they produce a balanced field at the flag to
reduce or eliminate any net lateral force on the flag. The electric
field coils are generally one or more metal coils, which generate a
magnetic field when electric current passes through the coil. The
iron flag is a flat or enlarged piece of magnetic material, which
increases the surface area of the lancet assembly to enhance the
magnetic forces generated between the proximal end of the lancet
and a magnetic field produced by the field coils. The combined mass
of the lancet and the iron flag can be minimized to facilitate
rapid acceleration for introduction into the skin of a patient, to
reduce the impact when the lancet stops in the skin, and to
facilitate prompt velocity profile changes throughout the sampling
cycle.
[0115] The stationary housing assembly consists of a PC board 20, a
lower inner insulating housing 22, an upper inner insulating
housing 32, an upper PC board 30, and rivets 18 assembled into a
single unit. The lower and upper inner insulating housing 22 and 32
are relieved to form a slot so that lancet assembly can be slid
into the driver assembly from the side perpendicular to the
direction of the lancet's advancement and retraction. This allows
the disposal of the lancet assembly and reuse of the stationary
housing assembly with another lancet assembly while avoiding
accidental lancet launches during replacement.
[0116] The electric field coils in the upper and lower stationary
housing 20 and 30 are fabricated in a multi-layer printed circuit
(PC) board. They may also be conventionally wound wire coils. A
Teflon.RTM. material, or other low friction insulating material is
used to construct the lower and upper inner insulating housing 22
and 32. Each insulating housing is mounted on the PC board to
provide electrical insulation and physical protection, as well as
to provide a low-friction guide for the lancet. The lower and upper
inner insulating housing 22 and 32 provide a reference surface with
a small gap so that the lancet assembly 24 and 26 can align with
the drive field coils in the PC board for good magnetic
coupling.
[0117] Rivets 18 connect the lower inner insulating housing 22 to
the lower stationary housing 20 and are made of magnetically
permeable material such as ferrite or steel, which serves to
concentrate the magnetic field. This mirrors the construction of
the upper inner insulating housing 32 and upper stationary housing
30. These rivets form the poles of the electric field coils. The PC
board is fabricated with multiple layers of coils or with multiple
boards. Each layer supports spiral traces around a central hole.
Alternate layers spiral from the center outwards or from the edges
inward. In this way each layer connects via simple feed-through
holes, and the current always travels in the same direction,
summing the ampere-turns.
[0118] The PC boards within the lower and upper stationary housings
20 and 30 are connected to the lower and upper inner insulating
housings 22 and 32 with the rivets 18. The lower and upper inner
insulating housings 22 and 32 expose the rivet heads on opposite
ends of the slot where the lancet assembly 24 and 26 travels. The
magnetic field lines from each rivet create magnetic poles at the
rivet heads. An iron bar on the opposite side of the PC board
within each of the lower and upper stationary housing 20 and 30
completes the magnetic circuit by connecting the rivets. Any
fastener made of magnetically permeable material such as iron or
steel can be used In place of the rivets. A single component made
of magnetically permeable material and formed in a horseshoe shape
can be used in place of the rivet/screw and iron bar assembly. In
operation, the magnetically permeable flag 26 attached to the
lancet 24 is divided into slits and bars 34. The slit patterns are
staggered so that coils can drive the flag 26 in two, three or more
phases.
[0119] Both lower and upper PC boards 20 and 30 contain drive coils
so that there is a symmetrical magnetic field above and below the
flag 26. When the pair of PC boards is turned on, a magnetic field
is established around the bars between the slits of the
magnetically permeable iron on the flag 26. The bars of the flag
experience a force that tends to move the magnetically permeable
material to a position minimizing the number and length of magnetic
field lines and conducting the magnetic field lines between the
magnetic poles.
[0120] When a bar of the flag 26 is centered between the rivets 18
of a magnetic pole, there is no net force on the flag, and any
disturbing force is resisted by imbalance in the field. This
embodiment of the device operates on a principle similar to that of
a solenoid. Solenoids cannot push by repelling iron; they can only
pull by attracting the iron into a minimum energy position. The
slits 34 on one side of the flag 26 are offset with respect to the
other side by approximately one half of the pitch of the poles. By
alternately activating the coils on each side of the PC board, the
lancet assembly can be moved with respect to the stationary housing
assembly. The direction of travel is established by selectively
energizing the coils adjacent the metal flag on the lancet
assembly. Alternatively, a three phase, three-pole design or a
shading coil that is offset by one-quarter pitch establishes the
direction of travel. The lower and upper PC boards 20 and 30 shown
in FIG. 4 contain electric field coils, which drive the lancet
assembly and the circuitry for controlling the entire
electromagnetic driver.
[0121] The embodiment described above generally uses the principles
of a magnetic attraction drive, similar to commonly available
circular stepper motors (Hurst Manufacturing BA Series motor, or
"Electrical Engineering Handbook" Second edition p 1472-1474,
1997). These references are hereby incorporated by reference. Other
embodiments can include a linear induction drive that uses a
changing magnetic field to induce electric currents in the lancet
assembly. These induced currents produce a secondary magnetic field
that repels the primary field and applies a net force on the lancet
assembly. The linear induction drive uses an electrical drive
control that sweeps a magnetic field from pole to pole, propelling
the lancet before it. Varying the rate of the sweep and the
magnitude of the field by altering the driving voltage and
frequency controls the force applied to the lancet assembly and its
velocity.
[0122] The arrangement of the coils and rivets to concentrate the
magnetic flux also applies to the induction design creating a
growing magnetic field as the electric current in the field
switches on. This growing magnetic field creates an opposing
electric current in the conductive flag. In a linear induction
motor the flag is electrically conductive, and its magnetic
properties are unimportant. Copper or aluminum are materials that
can be used for the conductive flags. Copper is generally used
because of its good electrical conductivity. The opposing
electrical field produces an opposing magnetic field that repels
the field of the coils. By phasing the power of the coils, a moving
field can be generated which pushes the flag along just below the
synchronous speed of the coils. By controlling the rate of sweep,
and by generating multiple sweeps, the flag can be moved at a
desired speed.
[0123] FIG. 5 shows another embodiment of a solenoid type
electromagnetic driver that is capable of driving an iron core or
slug mounted to the lancet assembly using a direct current (DC)
power supply. The electromagnetic driver includes a driver coil
pack that is divided into three separate coils along the path of
the lancet, two end coils and a middle coil. Direct current is
alternated to the coils to advance and retract the lancet. Although
the driver coil pack is shown with three coils, any suitable number
of coils may be used, for example, 4, 5, 6, 7 or more coils may be
used.
[0124] The stationary iron housing 40 contains the driver coil pack
with a first coil 52 is flanked by iron spacers 50 which
concentrate the magnetic flux at the inner diameter creating
magnetic poles. The inner insulating housing 48 isolates the lancet
42 and iron core 46 from the coils and provides a smooth, low
friction guide surface. The lancet guide 44 further centers the
lancet 42 and iron core 46. The lancet 42 is protracted and
retracted by alternating the current between the first coil 52, the
middle coil, and the third coil to attract the iron core 46.
Reversing the coil sequence and attracting the core and lancet back
into the housing retracts the lancet. The lancet guide 44 also
serves as a stop for the iron core 46 mounted to the lancet 42.
[0125] As discussed above, tissue penetration devices which employ
spring or cam driving methods have a symmetrical or nearly
symmetrical actuation displacement and velocity profiles on the
advancement and retraction of the lancet as shown in FIGS. 6 and 7.
In most of the available lancet devices, once the launch is
initiated, the stored energy determines the velocity profile until
the energy is dissipated. Controlling impact, retraction velocity,
and dwell time of the lancet within the tissue can be useful in
order to achieve a high success rate while accommodating variations
in skin properties and minimize pain. Advantages can be achieved by
taking into account that tissue dwell time is related to the amount
of skin deformation as the lancet tries to puncture the surface of
the skin and variance in skin deformation from patient to patient
based on skin hydration.
[0126] The ability to control velocity and depth of penetration can
be achieved by use of a controllable force driver where feedback is
an integral part of driver control. Such drivers can control either
metal or polymeric lancets or any other type of tissue penetration
element. The dynamic control of such a driver is illustrated in
FIG. 8 which illustrates an embodiment of a controlled displacement
profile and FIG. 9 which illustrates an embodiment of a the
controlled velocity profile. These are compared to FIGS. 6 and 7,
which illustrate embodiments of displacement and velocity profiles,
respectively, of a harmonic spring/mass powered driver.
[0127] Reduced pain can be achieved by using impact velocities of
greater than 2 m/s entry of a tissue penetrating element, such as a
lancet, into tissue.
[0128] Retraction of the lancet at a low velocity following the
sectioning of the venuole/capillary mesh allows the blood to flood
the wound tract and flow freely to the surface, thus using the
lancet to keep the channel open during retraction as shown in FIGS.
10 and 11. Low-velocity retraction of the lancet near the wound
flap prevents the wound flap from sealing off the channel. Thus,
the ability to slow the lancet retraction directly contributes to
increasing the success rate of obtaining blood. Increasing the
sampling success rate to near 100% can be important to the
combination of sampling and acquisition into an integrated sampling
module such as an integrated glucose-sampling module, which
incorporates a glucose test strip.
[0129] Referring again to FIG. 5, the lancet and lancet driver are
configured so that feedback control is based on lancet
displacement, velocity, or acceleration. The feedback control
information relating to the actual lancet path is returned to a
processor such as that illustrated in FIG. 12 that regulates the
energy to the driver, thereby precisely controlling the lancet
throughout its advancement and retraction. The driver may be driven
by electric current, which includes direct current and alternating
current.
[0130] In FIG. 5, the electromagnetic driver shown is capable of
driving an iron core or slug mounted to the lancet assembly using a
direct current (DC) power supply and is also capable of determining
the position of the iron core by measuring magnetic coupling
between the core and the coils. The coils can be used in pairs to
draw the iron core into the driver coil pack. As one of the coils
is switched on, the corresponding induced current in the adjacent
coil can be monitored. The strength of this induced current is
related to the degree of magnetic coupling provided by the iron
core, and can be used to infer the position of the core and hence,
the relative position of the lancet.
[0131] After a period of time, the drive voltage can be turned off,
allowing the coils to relax, and then the cycle is repeated. The
degree of magnetic coupling between the coils is converted
electronically to a proportional DC voltage that is supplied to an
analog-to-digital converter. The digitized position signal is then
processed and compared to a desired "nominal" position by a central
processing unit (CPU). The CPU to set the level and/or length of
the next power pulse to the solenoid coils uses error between the
actual and nominal positions.
[0132] In another embodiment, the driver coil pack has three coils
consisting of a central driving coil flanked by balanced detection
coils built into the driver assembly so that they surround an
actuation or magnetically active region with the region centered on
the middle coil at mid-stroke. When a current pulse is applied to
the central coil, voltages are induced in the adjacent sense coils.
If the sense coils are connected together so that their induced
voltages oppose each other, the resulting signal will be positive
for deflection from mid-stroke in one direction, negative in the
other direction, and zero at mid-stroke. This measuring technique
is commonly used in Linear Variable Differential Transformers
(LVDT). Lancet position is determined by measuring the electrical
balance between the two sensing coils.
[0133] In another embodiment, a feedback loop can use a
commercially available LED/photo transducer module such as the
OPB703 manufactured by Optek Technology, Inc., 1215 W. Crosby Road,
Carrollton, Tex., 75006 to determine the distance from the fixed
module on the stationary housing to a reflective surface or target
mounted on the lancet assembly. The LED acts as a light emitter to
send light beams to the reflective surface, which in turn reflects
the light back to the photo transducer, which acts as a light
sensor. Distances over the range of 4 mm or so are determined by
measuring the intensity of the reflected light by the photo
transducer. In another embodiment, a feedback loop can use a
magnetically permeable region on the lancet shaft itself as the
core of a Linear Variable Differential Transformer (LVDT).
[0134] A permeable region created by selectively annealing a
portion of the lancet shaft, or by including a component in the
lancet assembly, such as ferrite, with sufficient magnetic
permeability to allow coupling between adjacent sensing coils. Coil
size, number of windings, drive current, signal amplification, and
air gap to the permeable region are specified in the design
process. In another embodiment, the feedback control supplies a
piezoelectric driver, superimposing a high frequency oscillation on
the basic displacement profile. The piezoelectric driver provides
improved cutting efficiency and reduces pain by allowing the lancet
to "saw" its way into the tissue or to destroy cells with
cavitation energy generated by the high frequency of vibration of
the advancing edge of the lancet. The drive power to the
piezoelectric driver is monitored for an impedance shift as the
device interacts with the target tissue. The resulting force
measurement, coupled with the known mass of the lancet is used to
determine lancet acceleration, velocity, and position.
[0135] FIG. 12 illustrates the operation of a feedback loop using a
processor. The processor 60 stores profiles 62 in non-volatile
memory. A user inputs information 64 about the desired
circumstances or parameters for a lancing event. The processor 60
selects a driver profile 62 from a set of alternative driver
profiles that have been preprogrammed in the processor 60 based on
typical or desired tissue penetration device performance determined
through testing at the factory or as programmed in by the operator.
The processor 60 may customize by either scaling or modifying the
profile based on additional user input information 64. Once the
processor has chosen and customized the profile, the processor 60
is ready to modulate the power from the power supply 66 to the
lancet driver 68 through an amplifier 70. The processor 60 measures
the location of the lancet 72 using a position sensing mechanism 74
through an analog to digital converter 76. Examples of position
sensing mechanisms have been described in the embodiments above.
The processor 60 calculates the movement of the lancet by comparing
the actual profile of the lancet to the predetermined profile. The
processor 60 modulates the power to the lancet driver 68 through a
signal generator 78, which controls the amplifier 70 so that the
actual profile of the lancet does not exceed the predetermined
profile by more than a preset error limit. The error limit is the
accuracy in the control of the lancet.
[0136] After the lancing event, the processor 60 can allow the user
to rank the results of the lancing event. The processor 60 stores
these results and constructs a database 80 for the individual user.
Using the database 80, the processor 60 calculates the profile
traits such as degree of painlessness, success rate, and blood
volume for various profiles 62 depending on user input information
64 to optimize the profile to the individual user for subsequent
lancing cycles. These profile traits depend on the characteristic
phases of lancet advancement and retraction. The processor 60 uses
these calculations to optimize profiles 62 for each user. In
addition to user input information 64, an internal clock allows
storage in the database 80 of information such as the time of day
to generate a time stamp for the lancing event and the time between
lancing events to anticipate the user's diurnal needs. The database
stores information and statistics for each user and each profile
that particular user uses.
[0137] In addition to varying the profiles, the processor 60 can be
used to calculate the appropriate lancet diameter and geometry
necessary to realize the blood volume required by the user. For
example, if the user requires a 1-5 micro liter volume of blood,
the processor selects a 200 micron diameter lancet to achieve these
results. For each class of lancet, both diameter and lancet tip
geometry, is stored in the processor to correspond with upper and
lower limits of attainable blood volume based on the predetermined
displacement and velocity profiles.
[0138] The lancing device is capable of prompting the user for
information at the beginning and the end of the lancing event to
more adequately suit the user. The goal is to either change to a
different profile or modify an existing profile. Once the profile
is set, the force driving the lancet is varied during advancement
and retraction to follow the profile. The method of lancing using
the lancing device comprises selecting a profile, lancing according
to the selected profile, determining lancing profile traits for
each characteristic phase of the lancing cycle, and optimizing
profile traits for subsequent lancing events.
[0139] FIG. 13 shows an embodiment of the characteristic phases of
lancet advancement and retraction on a graph of force versus time
illustrating the force exerted by the lancet driver on the lancet
to achieve the desired displacement and velocity profile. The
characteristic phases are the lancet introduction phase A-C where
the lancet is longitudinally advanced into the skin, the lancet
rest phase D where the lancet terminates its longitudinal movement
reaching its maximum depth and becoming relatively stationary, and
the lancet retraction phase E-G where the lancet is longitudinally
retracted out of the skin. The duration of the lancet retraction
phase E-G is longer than the duration of the lancet introduction
phase A-C, which in turn is longer than the duration of the lancet
rest phase D.
[0140] The introduction phase further comprises a lancet launch
phase prior to A when the lancet is longitudinally moving through
air toward the skin, a tissue contact phase at the beginning of A
when the distal end of the lancet makes initial contact with the
skin, a tissue deformation phase A when the skin bends depending on
its elastic properties which are related to hydration and
thickness, a tissue lancing phase which comprises when the lancet
hits the inflection point on the skin and begins to cut the skin B
and the lancet continues cutting the skin C. The lancet rest phase
D is the limit of the penetration of the lancet into the skin. Pain
is reduced by minimizing the duration of the lancet introduction
phase A-C so that there is a fast incision to a certain penetration
depth regardless of the duration of the deformation phase A and
inflection point cutting B which will vary from user to user.
Success rate is increased by measuring the exact depth of
penetration from inflection point B to the limit of penetration in
the lancet rest phase D. This measurement allows the lancet to
always, or at least reliably, hit the capillary beds which are a
known distance underneath the surface of the skin.
[0141] The lancet retraction phase further comprises a primary
retraction phase E when the skin pushes the lancet out of the wound
tract, a secondary retraction phase F when the lancet starts to
become dislodged and pulls in the opposite direction of the skin,
and lancet exit phase G when the lancet becomes free of the skin.
Primary retraction is the result of exerting a decreasing force to
pull the lancet out of the skin as the lancet pulls away from the
finger. Secondary retraction is the result of exerting a force in
the opposite direction to dislodge the lancet. Control is necessary
to keep the wound tract open as blood flows up the wound tract.
Blood volume is increased by using a uniform velocity to retract
the lancet during the lancet retraction phase E-G regardless of the
force required for the primary retraction phase E or secondary
retraction phase F, either of which may vary from user to user
depending on the properties of the user's skin.
[0142] FIG. 14 shows a standard industry lancet for glucose testing
which has a three-facet geometry. Taking a rod of diameter 114 and
grinding 8 degrees to the plane of the primary axis to create the
primary facet 110 produces the lancet 116. The secondary facets 112
are then created by rotating the shaft of the needle 15 degrees,
and then rolling over 12 degrees to the plane of the primary facet.
Other possible geometry's require altering the lancet's production
parameters such as shaft diameter, angles, and translation
distance.
[0143] FIG. 15 illustrates facet and tip geometry 120 and 122,
diameter 124, and depth 126 which are significant factors in
reducing pain, blood volume and success rate. It is known that
additional cutting by the lancet is achieved by increasing the
shear percentage or ratio of the primary to secondary facets, which
when combined with reducing the lancet's diameter reduces skin tear
and penetration force and gives the perception of less pain.
Overall success rate of blood yield, however, also depends on a
variety of factors, including the existence of facets, facet
geometry, and skin anatomy.
[0144] FIG. 16 shows another embodiment of displacement versus time
profile of a lancet for a controlled lancet retraction. FIG. 17
shows the velocity vs. time profile of the lancet for the
controlled retraction of FIG. 16. The lancet driver controls lancet
displacement and velocity at several steps in the lancing cycle,
including when the lancet cuts the blood vessels to allow blood to
pool 130, and as the lancet retracts, regulating the retraction
rate to allow the blood to flood the wound tract while keeping the
wound flap from sealing the channel 132 to permit blood to exit the
wound.
[0145] In addition to slow retraction of a tissue-penetrating
element in order to hold the wound open to allow blood to escape to
the skin surface, other methods are contemplated. FIG. 18 shows the
use of an embodiment of the invention, which includes a retractable
coil on the lancet tip. A coiled helix or tube 140 is attached
externally to lancet 116 with the freedom to slide such that when
the lancet penetrates the skin 150, the helix or tube 140 follows
the trajectory of the lancet 116. The helix begins the lancing
cycle coiled around the facets and shaft of the lancet 144. As the
lancet penetrates the skin, the helix braces the wound tract around
the lancet 146. As the lancet retracts, the helix remains to brace
open the wound tract, keeping the wound tract from collapsing and
keeping the surface skin flap from closing 148. This allows blood
152 to pool and flow up the channel to the surface of the skin. The
helix is then retracted as the lancet pulls the helix to the point
where the helix is decompressed to the point where the diameter of
the helix becomes less than the diameter of the wound tract and
becomes dislodged from the skin.
[0146] The tube or helix 140 is made of wire or metal of the type
commonly used in angioplasty stents such as stainless steel, nickel
titanium alloy or the like. Alternatively the tube or helix 140 or
a ring can be made of a biodegradable material, which braces the
wound tract by becoming lodged in the skin. Biodegradation is
completed within seconds or minutes of insertion, allowing adequate
time for blood to pool and flow up the wound tract. Biodegradation
is activated by heat, moisture, or pH from the skin.
[0147] Alternatively, the wound could be held open by coating the
lancet with a powder or other granular substance. The powder coats
the wound tract and keeps it open when the lancet is withdrawn. The
powder or other granular substance can be a coarse bed of
microspheres or capsules which hold the channel open while allowing
blood to flow through the porous interstices.
[0148] In another embodiment the wound can be held open using a
two-part needle, the outer part in the shape of a "U" and the inner
part filling the "U." After creating the wound the inner needle is
withdrawn leaving an open channel, rather like the plugs that are
commonly used for withdrawing sap from maple trees.
[0149] FIG. 19 shows a further embodiment of a method and device
for facilitating blood flow utilizing an elastomer to coat the
wound. This method uses an elastomer 154, such as silicon rubber,
to coat or brace the wound tract 156 by covering and stretching the
surface of the finger 158. The elastomer 154 is applied to the
finger 158 prior to lancing. After a short delay, the lancet (not
shown) then penetrates the elastomer 154 and the skin on the
surface of the finger 158 as is seen in 160. Blood is allowed to
pool and rise to the surface while the elastomer 154 braces the
wound tract 156 as is seen in 162 and 164. Other known mechanisms
for increasing the success rate of blood yield after lancing can
include creating a vacuum, suctioning the wound, applying an
adhesive strip, vibration while cutting, or initiating a second
lance if the first is unsuccessful.
[0150] FIG. 20 illustrates an embodiment of a tissue penetration
device, more specifically, a lancing device 180 that includes a
controllable driver 179 coupled to a tissue penetration element.
The lancing device 180 has a proximal end 181 and a distal end 182.
At the distal end 182 is the tissue penetration element in the form
of a lancet 183, which is coupled to an elongate coupler shaft 184
by a drive coupler 185. The elongate coupler shaft 184 has a
proximal end 186 and a distal end 187. A driver coil pack 188 is
disposed about the elongate coupler shaft 184 proximal of the
lancet 183. A position sensor 191 is disposed about a proximal
portion 192 of the elongate coupler shaft 184 and an electrical
conductor 194 electrically couples a processor 193 to the position
sensor 191. The elongate coupler shaft 184 driven by the driver
coil pack 188 controlled by the position sensor 191 and processor
193 form the controllable driver, specifically, a controllable
electromagnetic driver.
[0151] Referring to FIG. 21, the lancing device 180 can be seen in
more detail, in partial longitudinal section. The lancet 183 has a
proximal end 195 and a distal end 196 with a sharpened point at the
distal end 196 of the lancet 183 and a drive head 198 disposed at
the proximal end 195 of the lancet 183. A lancet shaft 201 is
disposed between the drive head 198 and the sharpened point 197.
The lancet shaft 201 may be comprised of stainless steel, or any
other suitable material or alloy and have a transverse dimension of
about 0.1 to about 0.4 mm. The lancet shaft may have a length of
about 3 mm to about 50 mm, specifically, about 15 mm to about 20
mm. The drive head 198 of the lancet 183 is an enlarged portion
having a transverse dimension greater than a transverse dimension
of the lancet shaft 201 distal of the drive head 198. This
configuration allows the drive head 198 to be mechanically captured
by the drive coupler 185. The drive head 198 may have a transverse
dimension of about 0.5 to about 2 mm.
[0152] A magnetic member 202 is secured to the elongate coupler
shaft 184 proximal of the drive coupler 185 on a distal portion 203
of the elongate coupler shaft 184. The magnetic member 202 is a
substantially cylindrical piece of magnetic material having an
axial lumen 204 extending the length of the magnetic member 202.
The magnetic member 202 has an outer transverse dimension that
allows the magnetic member 202 to slide easily within an axial
lumen 205 of a low friction, possibly lubricious, polymer guide
tube 205' disposed within the driver coil pack 188. The magnetic
member 202 may have an outer transverse dimension of about 1.0 to
about 5.0 mm, specifically, about 2.3 to about 2.5 mm. The magnetic
member 202 may have a length of about 3.0 to about 5.0 mm,
specifically, about 4.7 to about 4.9 mm. The magnetic member 202
can be made from a variety of magnetic materials including ferrous
metals such as ferrous steel, iron, ferrite, or the like. The
magnetic member 202 may be secured to the distal portion 203 of the
elongate coupler shaft 184 by a variety of methods including
adhesive or epoxy bonding, welding, crimping or any other suitable
method.
[0153] Proximal of the magnetic member 202, an optical encoder flag
206 is secured to the elongate coupler shaft 184. The optical
encoder flag 206 is configured to move within a slot 207 in the
position sensor 191. The slot 207 of the position sensor 191 is
formed between a first body portion 208 and a second body portion
209 of the position sensor 191. The slot 207 may have separation
width of about 1.5 to about 2.0 mm. The optical encoder flag 206
can have a length of about 14 to about 18 mm, a width of about 3 to
about 5 mm and a thickness of about 0.04 to about 0.06 mm.
[0154] The optical encoder flag 206 interacts with various optical
beams generated by LEDs disposed on or in the position sensor body
portions 208 and 209 in a predetermined manner. The interaction of
the optical beams generated by the LEDs of the position sensor 191
generates a signal that indicates the longitudinal position of the
optical flag 206 relative to the position sensor 191 with a
substantially high degree of resolution. The resolution of the
position sensor 191 may be about 200 to about 400 cycles per inch,
specifically, about 350 to about 370 cycles per inch. The position
sensor 191 may have a speed response time (position/time
resolution) of 0 to about 120,000 Hz, where one dark and light
stripe of the flag constitutes one Hertz, or cycle per second. The
position of the optical encoder flag 206 relative to the magnetic
member 202, driver coil pack 188 and position sensor 191 is such
that the optical encoder 191 can provide precise positional
information about the lancet 183 over the entire length of the
lancet's power stroke.
[0155] An optical encoder that is suitable for the position sensor
191 is a linear optical incremental encoder, model HEDS 9200,
manufactured by Agilent Technologies. The model HEDS 9200 may have
a length of about 20 to about 30 mm, a width of about 8 to about 12
mm, and a height of about 9 to about 11 mm. Although the position
sensor 191 illustrated is a linear optical incremental encoder,
other suitable position sensor embodiments could be used, provided
they posses the requisite positional resolution and time response.
The HEDS 9200 is a two channel device where the channels are 90
degrees out of phase with each other. This results in a resolution
of four times the basic cycle of the flag. These quadrature outputs
make it possible for the processor to determine the direction of
lancet travel. Other suitable position sensors include capacitive
encoders, analog reflective sensors, such as the reflective
position sensor discussed above, and the like.
[0156] A coupler shaft guide 211 is disposed towards the proximal
end 181 of the lancing device 180. The guide 211 has a guide lumen
212 disposed in the guide 211 to slidingly accept the proximal
portion 192 of the elongate coupler shaft 184. The guide 211 keeps
the elongate coupler shaft 184 centered horizontally and vertically
in the slot 202 of the optical encoder 191.
[0157] The driver coil pack 188, position sensor 191 and coupler
shaft guide 211 are all secured to a base 213. The base 213 is
longitudinally coextensive with the driver coil pack 188, position
sensor 191 and coupler shaft guide 211. The base 213 can take the
form of a rectangular piece of metal or polymer, or may be a more
elaborate housing with recesses, which are configured to accept the
various components of the lancing device 180.
[0158] As discussed above, the magnetic member 202 is configured to
slide within an axial lumen 205 of the driver coil pack 188. The
driver coil pack 188 includes a most distal first coil 214, a
second coil 215, which is axially disposed between the first coil
214 and a third coil 216, and a proximal-most fourth coil 217. Each
of the first coil 214, second coil 215, third coil 216 and fourth
coil 217 has an axial lumen. The axial lumens of the first through
fourth coils are configured to be coaxial with the axial lumens of
the other coils and together form the axial lumen 205 of the driver
coil pack 188 as a whole. Axially adjacent each of the coils
214-217 is a magnetic disk or washer 218 that augments completion
of the magnetic circuit of the coils 214-217 during a lancing cycle
of the device 180. The magnetic washers 218 of the embodiment of
FIG. 21 are made of ferrous steel but could be made of any other
suitable magnetic material, such as iron or ferrite. The outer
shell 189 of the driver coil pack 188 is also made of iron or steel
to complete the magnetic path around the coils and between the
washers 218. The magnetic washers 218 have an outer diameter
commensurate with an outer diameter of the driver coil pack 188 of
about 4.0 to about 8.0 mm. The magnetic washers 218 have an axial
thickness of about 0.05, to about 0.4 mm, specifically, about 0.15
to about 0.25 mm.
[0159] Wrapping or winding an elongate electrical conductor 221
about an axial lumen until a sufficient number of windings have
been achieved forms the coils 214-217. The elongate electrical
conductor 221 is generally an insulated solid copper wire with a
small outer transverse dimension of about 0.06 mm to about 0.88 mm,
specifically, about 0.3 mm to about 0.5 mm. In one embodiment, 32
gauge copper wire is used for the coils 214-217. The number of
windings for each of the coils 214-217 of the driver pack 188 may
vary with the size of the coil, but for some embodiments each coil
214-217 may have about 30 to about 80 turns, specifically, about 50
to about 60 turns. Each coil 214-217 can have an axial length of
about 1.0 to about 3.0 mm, specifically, about 1.8 to about 2.0 mm.
Each coil 214-217 can have an outer transverse dimension or
diameter of about 4.0, to about 2.0 mm, specifically, about 9.0 to
about 12.0 mm. The axial lumen 205 can have a transverse dimension
of about 1.0 to about 3.0 mm.
[0160] It may be advantageous in some driver coil 188 embodiments
to replace one or more of the coils with permanent magnets, which
produce a magnetic field similar to that of the coils when the
coils are activated. In particular, it may be desirable in some
embodiments to replace the second coil 215, the third coil 216 or
both with permanent magnets. In addition, it may be advantageous to
position a permanent magnet at or near the proximal end of the coil
driver pack in order to provide fixed magnet zeroing function for
the magnetic member (Adams magnetic Products 23A0002 flexible
magnet material (800) 747-7543).
[0161] FIGS. 20 and 21 show a permanent bar magnet 219 disposed on
the proximal end of the driver coil pack 188. As shown in FIG. 21,
the bar magnet 219 is arranged so as to have one end disposed
adjacent the travel path of the magnetic member 202 and has a
polarity configured so as to attract the magnetic member 202 in a
centered position with respect to the bar magnet 219. Note that the
polymer guide tube 205' can be configured to extend proximally to
insulate the inward radial surface of the bar magnet 219 from an
outer surface of the magnetic member 202. This arrangement allows
the magnetic member 219 and thus the elongate coupler shaft 184 to
be attracted to and held in a zero point or rest position without
the consumption of electrical energy from the power supply 225.
[0162] Having a fixed zero or start point for the elongate coupler
shaft 184 and lancet 183 can be critical to properly controlling
the depth of penetration of the lancet 183 as well as other lancing
parameters. This can be because some methods of depth penetration
control for a controllable driver measure the acceleration and
displacement of the elongate coupler shaft 184 and lancet 183 from
a known start position. If the distance of the lancet tip 196 from
the target tissue is known, acceleration and displacement of the
lancet is known and the start position of the lancet is know, the
time and position of tissue contact and depth of penetration can be
determined by the processor 193.
[0163] Any number of configurations for a magnetic bar 219 can be
used for the purposes discussed above. In particular, a second
permanent bar magnet (not shown) could be added to the proximal end
of the driver coil pack 188 with the magnetic fields of the two bar
magnets configured to complement each other. In addition, a disc
magnet 219' could be used as illustrated in FIG. 22. Disc magnet
219' is shown disposed at the proximal end of the driver coiled
pack 188 with a polymer non-magnetic disc 219'' disposed between
the proximal-most coil 217 and disc magnet 219' and positions disc
magnet 219' away from the proximal end of the proximal-most coil
217. The polymer non-magnetic disc spacer 219'' is used so that the
magnetic member 202 can be centered in a zero or start position
slightly proximal of the proximal-most coil 217 of the driver coil
pack 188. This allows the magnetic member to be attracted by the
proximal-most coil 217 at the initiation of the lancing cycle
instead of being passive in the forward drive portion of the
lancing cycle.
[0164] An inner lumen of the polymer non-magnetic disc 219'' can be
configured to allow the magnetic member 202 to pass axially there
through while an inner lumen of the disc magnet 219' can be
configured to allow the elongate coupler shaft 184 to pass through
but not large enough for the magnetic member 202 to pass through.
This results in the magnetic member 202 being attracted to the disc
magnet 219' and coming to rest with the proximal surface of the
magnetic member 202 against a distal surface of the disc magnet
219'. This arrangement provides for a positive and repeatable stop
for the magnetic member, and hence the lancet. A similar
configuration could also be used for the bar magnet 219 discussed
above.
[0165] Typically, when the electrical current in the coils 214-217
of the driver coil pack 188 is off, a magnetic member 202 made of
soft iron is attracted to the bar magnet 219 or disc magnet 219'.
The magnetic field of the driver coil pack 188 and the bar magnet
219 or disc magnet 219', or any other suitable magnet, can be
configured such that when the electrical current in the coils
214-217 is turned on, the leakage magnetic field from the coils
214-217 has the same polarity as the bar magnet 219 or disc magnet
219'. This results in a magnetic force that repels the magnetic
member 202 from the bar magnet 219 or disc magnet 219' and attracts
the magnetic member 202 to the activated coils 214-217. For this
configuration, the bar magnet 219 or disc magnet thus act to
facilitate acceleration of the magnetic member 202 as opposed to
working against the acceleration.
[0166] Electrical conductors 222 couple the driver coil pack 188
with the processor 193 which can be configured or programmed to
control the current flow in the coils 214-217 of the driver coil
pack 188 based on position feedback from the position sensor 191,
which is coupled to the processor 193 by electrical conductors 194.
A power source 225 is electrically coupled to the processor 193 and
provides electrical power to operate the processor 193 and power
the coil driver pack 188. The power source 225 may be one or more
batteries that provide direct current power to the 193
processor.
[0167] FIG. 23 shows a transverse cross sectional view of drive
coupler 185 in more detail. The drive head 198 of the lancet 183 is
disposed within the drive coupler 185 with a first retaining rail
226 and second retaining rail 227 capturing the drive head 198
while allowing the drive head 198 to be inserted laterally into the
drive coupler 185 and retracted laterally with minimal mechanical
resistance. The drive coupler 185 may optionally be configured to
include snap ridges 228 which allow the drive head 198 to be
laterally inserted and retracted, but keep the drive head 198 from
falling out of the drive coupler 185 unless a predetermined amount
of externally applied lateral force is applied to the drive head
198 of the lancet 183 towards the lateral opening 231 of the drive
coupler 185. FIG. 27 shows an enlarged side view into the coupler
opening 231 of the drive coupler 185 showing the snap ridges 228
disposed in the lateral opening 231 and the retaining rails 226 and
227. FIG. 28 shows an enlarged front view of the drive coupler 185.
The drive coupler 185 can be made from an alloy such as stainless
steel, titanium or aluminum, but may also be made from a suitable
polymer such as ABS, PVC, polycarbonate plastic or the like. The
drive coupler may be open on both sides allowing the drive head and
lancet to pass through.
[0168] Referring to FIG. 24, the magnetic member 202 is disposed
about and secured to the elongate coupler shaft 184. The magnetic
member 202 is disposed within the axial lumen 232 of the fourth
coil 217. The driver coil pack 188 is secured to the base 213. In
FIG. 25 the position sensor 191 is secured to the base 213 with the
first body portion 208 of the position sensor 191 disposed opposite
the second body portion 209 of the position sensor 191 with the
first and second body portions 208 and 209 of the position sensor
191 separated by the gap or slot 207. The elongate coupler shaft
184 is slidably disposed within the gap 207 between the first and
second body portions 208 and 209 of the position sensor 191. The
optical encoder flag 206 is secured to the elongate coupler shaft
184 and disposed between the first body portion 208 and second body
portion 209 of the position sensor 191. Referring to FIG. 26, the
proximal portion 192 of the elongate coupler shaft 184 is disposed
within the guide lumen 212 of the coupler shaft guide 211. The
guide lumen 212 of the coupler shaft guide 211 may be lined with a
low friction material such as Teflon.RTM. or the like to reduce
friction of the elongate coupler shaft 184 during the power stroke
of the lancing device 180.
[0169] Referring to FIGS. 29A-29C, a flow diagram is shown that
describes the operations performed by the processor 193 in
controlling the lancet 183 of the lancing device 180 discussed
above during an operating cycle. FIGS. 30-36 illustrate the
interaction of the lancet 183 and skin 233 of the patient's finger
234 during an operation cycle of the lancet device 183. The
processor 193 operates under control of programming steps that are
stored in an associated memory. When the programming steps are
executed, the processor 193 performs operations as described
herein. Thus, the programming steps implement the functionality of
the operations described with respect to the flow diagram of FIG.
29. The processor 193 can receive the programming steps from a
program product stored in recordable media, including a direct
access program product storage device such as a hard drive or flash
ROM, a removable program product storage device such as a floppy
disk, or in any other manner known to those of skill in the art.
The processor 193 can also download the programming steps through a
network connection or serial connection.
[0170] In the first operation, represented by the flow diagram box
numbered 245 in FIG. 29A, the processor 193 initializes values that
it stores in memory relating to control of the lancet, such as
variables that it uses to keep track of the controllable driver 179
during movement. For example, the processor may set a clock value
to zero and a lancet position value to zero or to some other
initial value. The processor 193 may also cause power to be removed
from the coil pack 188 for a period of time, such as for about 10
ms, to allow any residual flux to dissipate from the coils.
[0171] In the initialization operation, the processor 193 also
causes the lancet to assume an initial stationary position. When in
the initial stationary position, the lancet 183 is typically fully
retracted such that the magnetic member 202 is positioned
substantially adjacent the fourth coil 217 of the driver coil pack
188, shown in FIG. 21 above. The processor 193 can move the lancet
183 to the initial stationary position by pulsing an electrical
current to the fourth coil 217 to thereby attract the magnetic
member 202 on the lancet 183 to the fourth coil 217. Alternatively,
the magnetic member can be positioned in the initial stationary
position by virtue of a permanent magnet, such as bar magnet 219,
disc magnet 219' or any other suitable magnet as discussed above
with regard to the tissue penetration device illustrated in FIGS.
20 and 21.
[0172] In the next operation, represented by the flow diagram box
numbered 247, the processor 193 energizes one or more of the coils
in the coil pack 188. This should cause the lancet 183 to begin to
move (i.e., achieve a non-zero speed) toward the skin target 233.
The processor 193 then determines whether or not the lancet is
indeed moving, as represented by the decision box numbered 249. The
processor 193 can determine whether the lancet 183 is moving by
monitoring the position of the lancet 183 to determine whether the
position changes over time. The processor 193 can monitor the
position of the lancet 183 by keeping track of the position of the
optical encoder flag 206 secured to the elongate coupler shaft 184
wherein the encoder 191 produces a signal coupled to the processor
193 that indicates the spatial position of the lancet 183.
[0173] If the processor 193 determines (via timeout without motion
events) that the lancet 183 is not moving (a "No" result from the
decision box 249), then the process proceeds to the operation
represented by the flow diagram box numbered 253, where the
processor deems that an error condition is present. This means that
some error in the system is causing the lancet 183 not to move. The
error may be mechanical, electrical, or software related. For
example, the lancet 183 may be stuck in the stationary position
because something is impeding its movement.
[0174] If the processor 193 determines that the lancet 183 is
indeed moving (a "Yes" result from the decision box numbered 249),
then the process proceeds to the operation represented by the flow
diagram box numbered 257. In this operation, the processor 193
causes the lancet 183 to continue to accelerate and launch toward
the skin target 233, as indicated by the arrow 235 in FIG. 30. The
processor 193 can achieve acceleration of the lancet 183 by sending
an electrical current to an appropriate coil 214-217 such that the
coil 214-217 exerts an attractive magnetic launching force on the
magnetic member 202 and causes the magnetic member 202 and the
lancet 183 coupled thereto to move in a desired direction. For
example, the processor 193 can cause an electrical current to be
sent to the third coil 216 so that the third coil 216 attracts the
magnetic member 202 and causes the magnetic member 202 to move from
a position adjacent the fourth coil 217 toward the third coil 216.
The processor preferably determines which coil 214-217 should be
used to attract the magnetic member 202 based on the position of
the magnetic member 202 relative to the coils 214-217. In this
manner, the processor 193 provides a controlled force to the lancet
that controls the movement of the lancet.
[0175] During this operation, the processor 193 periodically or
continually monitors the position and/or velocity of the lancet
183. In keeping track of the velocity and position of the lancet
183 as the lancet 183 moves towards the patient's skin 233 or other
tissue, the processor 193 also monitors and adjusts the electrical
current to the coils 214-217. In some embodiments, the processor
193 applies current to an appropriate coil 214-217 such that the
lancet 183 continues to move according to a desired direction and
acceleration. In the instant case, the processor 193 applies
current to the appropriate coil 214-217 that will cause the lancet
183 to continue to move in the direction of the patient's skin 233
or other tissue to be penetrated.
[0176] The processor 193 may successively transition the current
between coils 214-217 so that as the magnetic member 202 moves past
a particular coil 214-217, the processor 193 then shuts off current
to that coil 214-217 and then applies current to another coil
214-217 that will attract the magnetic member 202 and cause the
magnetic member 202 to continue to move in the desired direction.
In transitioning current between the coils 214-217, the processor
193 can take into account various factors, including the speed of
the lancet 183, the position of the lancet 183 relative to the
coils 214-217, the number of coils 214-217, and the level of
current to be applied to the coils 214-217 to achieve a desired
speed or acceleration.
[0177] In the next operation, the processor 193 determines whether
the cutting or distal end tip 196 of the lancet 183 has contacted
the patient's skin 233, as shown in FIG. 31 and as represented by
the decision box numbered 265 in FIG. 29B. The processor 193 may
determine whether the lancet 183 has made contact with the target
tissue 233 by a variety of methods, including some that rely on
parameters which are measured prior to initiation of a lancing
cycle and other methods that are adaptable to use during a lancing
cycle without any predetermined parameters.
[0178] In one embodiment, the processor 193 determines that the
skin has been contacted when the end tip 196 of the lancet 183 has
moved a predetermined distance with respect to its initial
position. If the distance from the tip 961 of the lancet 183 to the
target tissue 233 is known prior to initiation of lancet 183
movement, the initial position of the lancet 183 is fixed and
known, and the movement and position of the lancet 183 can be
accurately measured during a lancing cycle, then the position and
time of lancet contact can be determined.
[0179] This method requires an accurate measurement of the distance
between the lancet tip 196 and the patient's skin 233 when the
lancet 183 is in the zero time or initial position. This can be
accomplished in a number of ways. One way is to control all of the
mechanical parameters that influence the distance from the lancet
tip 196 to the patient's tissue or a surface of the lancing device
180 that will contact the patient's skin 233. This could include
the start position of the magnetic member 202, magnetic path
tolerance, magnetic member 202 dimensions, driver coil pack 188
location within the lancing device 180 as a whole, length of the
elongate coupling shaft 184, placement of the magnetic member 202
on the elongate coupling shaft 184, length of the lancet 183
etc.
[0180] If all these parameters, as well as others can be suitably
controlled in manufacturing with a tolerance stack-up that is
acceptable, then the distance from the lancet tip 196 to the target
tissue 233 can be determined at the time of manufacture of the
lancing device 180. The distance could then be programmed into the
memory of the processor 193. If an adjustable feature is added to
the lancing device 180, such as an adjustable length elongate
coupling shaft 184, this can accommodate variations in all of the
parameters noted above, except length of the lancet 183. An
electronic alternative to this mechanical approach would be to
calibrate a stored memory contact point into the memory of the
processor 193 during manufacture based on the mechanical parameters
described above.
[0181] In another embodiment, moving the lancet tip 196 to the
target tissue 233 very slowly and gently touching the skin 233
prior to actuation can accomplish the distance from the lancet tip
196 to the tissue 233. The position sensor can accurately measure
the distance from the initialization point to the point of contact,
where the resistance to advancement of the lancet 183 stops the
lancet movement. The lancet 183 is then retracted to the
initialization point having measured the distance to the target
tissue 233 without creating any discomfort to the user.
[0182] In another embodiment, the processor 193 may use software to
determine whether the lancet 183 has made contact with the
patient's skin 233 by measuring for a sudden reduction in velocity
of the lancet 183 due to friction or resistance imposed on the
lancet 183 by the patient's skin 233. The optical encoder 191
measures displacement of the lancet 183. The position output data
provides input to the interrupt input of the processor 193. The
processor 193 also has a timer capable of measuring the time
between interrupts. The distance between interrupts is known for
the optical encoder 191, so the velocity of the lancet 183 can be
calculated by dividing the distance between interrupts by the time
between the interrupts.
[0183] This method requires that velocity losses to the lancet 183
and elongate coupler 184 assembly due to friction are known to an
acceptable level so that these velocity losses and resulting
deceleration can be accounted for when establishing a deceleration
threshold above which contact between lancet tip 196 and target
tissue 233 will be presumed. This same concept can be implemented
in many ways. For example, rather than monitoring the velocity of
the lancet 183, if the processor 193 is controlling the lancet
driver in order to maintain a fixed velocity, the power to the
driver 188 could be monitored. If an amount of power above a
predetermined threshold is required in order to maintain a constant
velocity, then contact between the tip of the lancet 196 and the
skin 233 could be presumed.
[0184] In yet another embodiment, the processor 193 determines skin
233 contact by the lancet 183 by detection of an acoustic signal
produced by the tip 196 of the lancet 183 as it strikes the
patient's skin 233. Detection of the acoustic signal can be
measured by an acoustic detector 236 placed in contact with the
patient's skin 233 adjacent a lancet penetration site 237, as shown
in FIG. 31. Suitable acoustic detectors 236 include piezo electric
transducers, microphones and the like. The acoustic detector 236
transmits an electrical signal generated by the acoustic signal to
the processor 193 via electrical conductors 238. In another
embodiment, contact of the lancet 183 with the patient's skin 233
can be determined by measurement of electrical continuity in a
circuit that includes the lancet 183, the patient's finger 234 and
an electrical contact pad 240 that is disposed on the patient's
skin 233 adjacent the contact site 237 of the lancet 183, as shown
in FIG. 31. In this embodiment, as soon as the lancet 183 contacts
the patient's skin 233, the circuit 239 is completed and current
flows through the circuit 239. Completion of the circuit 239 can
then be detected by the processor 193 to confirm skin 233 contact
by the lancet 183.
[0185] If the lancet 183 has not contacted the target skin 233,
then the process proceeds to a timeout operation, as represented by
the decision box numbered 267 in FIG. 29B. In the timeout
operation, the processor 193 waits a predetermined time period. If
the timeout period has not yet elapsed (a "No" outcome from the
decision box 267), then the processor continues to monitor whether
the lancet has contacted the target skin 233. The processor 193
preferably continues to monitor the position and speed of the
lancet 183, as well as the electrical current to the appropriate
coil 214-217 to maintain the desired lancet 183 movement.
[0186] If the timeout period elapses without the lancet 183
contacting the skin (a "Yes" output from the decision box 267),
then it is deemed that the lancet 183 will not contact the skin and
the process proceeds to a withdraw phase, where the lancet is
withdrawn away from the skin 233, as discussed more fully below.
The lancet 183 may not have contacted the target skin 233 for a
variety of reasons, such as if the patient removed the skin 233
from the lancing device or if something obstructed the lancet 183
prior to it contacting the skin.
[0187] The processor 193 may also proceed to the withdraw phase
prior to skin contact for other reasons. For example, at some point
after initiation of movement of the lancet 183, the processor 193
may determine that the forward acceleration of the lancet 183
towards the patient's skin 233 should be stopped or that current to
all coils 214-217 should be shut down. This can occur, for example,
if it is determined that the lancet 183 has achieved sufficient
forward velocity, but has not yet contacted the skin 233. In one
embodiment, the average penetration velocity of the lancet 183 from
the point of contact with the skin to the point of maximum
penetration may be about 2.0 to about 10.0 m/s, specifically, about
3.8 to about 4.2 m/s. In another embodiment, the average
penetration velocity of the lancet may be from about 2 to about 8
meters per second, specifically, about 2 to about 4 m/s.
[0188] The processor 193 can also proceed to the withdraw phase if
it is determined that the lancet 183 has fully extended to the end
of the power stroke of the operation cycle of lancing procedure. In
other words, the process may proceed to withdraw phase when an
axial center 241 of the magnetic member 202 has moved distal of an
axial center 242 of the first coil 214 as show in FIG. 21. In this
situation, any continued power to any of the coils 214-217 of the
driver coil pack 188 serves to decelerate the magnetic member 202
and thus the lancet 183. In this regard, the processor 193
considers the length of the lancet 183 (which can be stored in
memory) the position of the lancet 183 relative to the magnetic
member 202, as well as the distance that the lancet 183 has
traveled.
[0189] With reference again to the decision box 265 in FIG. 29B, if
the processor 193 determines that the lancet 183 has contacted the
skin 233 (a "Yes" outcome from the decision box 265), then the
processor 193 can adjust the speed of the lancet 183 or the power
delivered to the lancet 183 for skin penetration to overcome any
frictional forces on the lancet 183 in order to maintain a desired
penetration velocity of the lancet. The flow diagram box numbered
267 represents this.
[0190] As the velocity of the lancet 183 is maintained after
contact with the skin 233, the distal tip 196 of the lancet 183
will first begin to depress or tent the contacted skin 237 and the
skin 233 adjacent the lancet 183 to form a tented portion 243 as
shown in FIG. 32 and further shown in FIG. 33. As the lancet 183
continues to move in a distal direction or be driven in a distal
direction against the patient's skin 233, the lancet 183 will
eventually begin to penetrate the skin 233, as shown in FIG. 34.
Once penetration of the skin 233 begins, the static force at the
distal tip 196 of the lancet 183 from the skin 233 will become a
dynamic cutting force, which is generally less than the static tip
force. As a result in the reduction of force on the distal tip 196
of the lancet 183 upon initiation of cutting, the tented portion
243 of the skin 233 adjacent the distal tip 196 of the lancet 183
which had been depressed as shown in FIGS. 32 and 24 will spring
back as shown in FIG. 34.
[0191] In the next operation, represented by the decision box
numbered 271 in FIG. 29B, the processor 193 determines whether the
distal end 196 of the lancet 183 has reached a brake depth. The
brake depth is the skin penetration depth for which the processor
193 determines that deceleration of the lancet 183 is to be
initiated in order to achieve a desired final penetration depth 244
of the lancet 183 as show in FIG. 35. The brake depth may be
pre-determined and programmed into the processor's memory, or the
processor 193 may dynamically determine the brake depth during the
actuation. The amount of penetration of the lancet 183 in the skin
233 of the patient may be measured during the operation cycle of
the lancet device 180. In addition, as discussed above, the
penetration depth necessary for successfully obtaining a useable
sample can depend on the amount of tenting of the skin 233 during
the lancing cycle. The amount of tenting of the patient's skin 233
can in turn depend on the tissue characteristics of the patient
such as elasticity, hydration etc. A method for determining these
characteristics is discussed below with regard to skin 233 tenting
measurements during the lancing cycle and illustrated in FIGS.
37-41.
[0192] Penetration measurement can be carried out by a variety of
methods that are not dependent on measurement of tenting of the
patient's skin. In one embodiment, the penetration depth of the
lancet 183 in the patient's skin 233 is measured by monitoring the
amount of capacitance between the lancet 183 and the patient's skin
233. In this embodiment, a circuit includes the lancet 183, the
patient's finger 234, the processor 193 and electrical conductors
connecting these elements. As the lancet 183 penetrates the
patient's skin 233, the greater the amount of penetration, the
greater the surface contact area between the lancet 183 and the
patient's skin 233. As the contact area increases, so does the
capacitance between the skin 233 and the lancet 183. The increased
capacitance can be easily measured by the processor 193 using
methods known in the art and penetration depth can then be
correlated to the amount of capacitance. The same method can be
used by measuring the electrical resistance between the lancet 183
and the patient's skin.
[0193] If the brake depth has not yet been reached, then a "No"
results from the decision box 271 and the process proceeds to the
timeout operation represented by the flow diagram box numbered 273.
In the timeout operation, the processor 193 waits a predetermined
time period. If the timeout period has not yet elapsed (a "No"
outcome from the decision box 273), then the processor continues to
monitor whether the brake depth has been reached. If the timeout
period elapses without the lancet 183 achieving the brake depth (a
"Yes" output from the decision box 273), then the processor 193
deems that the lancet 183 will not reach the brake depth and the
process proceeds to the withdraw phase, which is discussed more
fully below. This may occur, for example, if the lancet 183 is
stuck at a certain depth.
[0194] With reference again to the decision box numbered 271 in
FIG. 29B, if the lancet does reach the brake depth (a "Yes"
result), then the process proceeds to the operation represented by
the flow diagram box numbered 275. In this operation, the processor
193 causes a braking force to be applied to the lancet to thereby
reduce the speed of the lancet 183 to achieve a desired amount of
final skin penetration depth 244, as shown in FIG. 26. Note that
FIGS. 32 and 33 illustrate the lancet making contact with the
patient's skin and deforming or depressing the skin prior to any
substantial penetration of the skin. The speed of the lancet 183 is
preferably reduced to a value below a desired threshold and is
ultimately reduced to zero. The processor 193 can reduce the speed
of the lancet 183 by causing a current to be sent to a 214-217 coil
that will exert an attractive braking force on the magnetic member
202 in a proximal direction away from the patient's tissue or skin
233, as indicated by the arrow 290 in FIG. 36. Such a negative
force reduces the forward or distally oriented speed of the lancet
183. The processor 193 can determine which coil 214-217 to energize
based upon the position of the magnetic member 202 with respect to
the coils 214-217 of the driver coil pack 188, as indicated by the
position sensor 191.
[0195] In the next operation, the process proceeds to the withdraw
phase, as represented by the flow diagram box numbered 277. The
withdraw phase begins with the operation represented by the flow
diagram box numbered 279 in FIG. 29C. Here, the processor 193
allows the lancet 183 to settle at a position of maximum skin
penetration 244, as shown in FIG. 35. In this regard, the processor
193 waits until any motion in the lancet 183 (due to vibration from
impact and spring energy stored in the skin, etc.) has stopped by
monitoring changes in position of the lancet 183. The processor 193
preferably waits until several milliseconds (ms), such as on the
order of about 8 ms, have passed with no changes in position of the
lancet 183. This is an indication that movement of the lancet 183
has ceased entirely. In some embodiments, the lancet may be allowed
to settle for about 1 to about 2000 milliseconds, specifically,
about 50 to about 200 milliseconds. For other embodiments, the
settling time may be about 1 to about 200 milliseconds.
[0196] It is at this stage of the lancing cycle that a software
method can be used to measure the amount of tenting of the
patient's skin 233 and thus determine the skin 233 characteristics
such as elasticity, hydration and others. Referring to FIGS. 37-41,
a lancet 183 is illustrated in various phases of a lancing cycle
with target tissue 233. FIG. 37 shows tip 196 of lancet 183 making
initial contact with the skin 233 at the point of initial
impact.
[0197] FIG. 38 illustrates an enlarged view of the lancet 183
making initial contact with the tissue 233 shown in FIG. 37. In
FIG. 39, the lancet tip 196 has depressed or tented the skin 233
prior to penetration over a distance of X, as indicated by the
arrow labeled X in FIG. 39. In FIG. 40, the lancet 183 has reached
the full length of the cutting power stroke and is at maximum
displacement. In this position, the lancet tip 196 has penetrated
the tissue 233 a distance of Y, as indicated by the arrow labeled Y
in FIG. 39. As can be seen from comparing FIG. 38 with FIG. 40, the
lancet tip 196 was displaced a total distance of X plus Y from the
time initial contact with the skin 233 was made to the time the
lancet tip 196 reached its maximum extension as shown in FIG. 40.
However, the lancet tip 196 has only penetrated the skin 233 a
distance Y because of the tenting phenomenon.
[0198] At the end of the power stroke of the lancet 183, as
discussed above with regard to FIG. 26 and box 279 of FIG. 29C, the
processor 193 allows the lancet to settle for about 8 msec. It is
during this settling time that the skin 233 rebounds or relaxes
back to approximately its original configuration prior to contact
by the lancet 183 as shown in FIG. 41. The lancet tip 196 is still
buried in the skin to a depth of Y, as shown in FIG. 41, however
the elastic recoil of the tissue has displaced the lancet rearward
or retrograde to the point of inelastic tenting that is indicated
by the arrows Z in FIG. 41. During the rearward displacement of the
lancet 183 due to the elastic tenting of the tissue 233, the
processor reads and stores the position data generated by the
position sensor 191 and thus measures the amount of elastic
tenting, which is the difference between X and Z.
[0199] The tenting process and retrograde motion of the lancet 183
during the lancing cycle is illustrated graphically in FIG. 42
which shows both a velocity versus time graph and a position versus
time graph of a lancet tip 196 during a lancing cycle that includes
elastic and inelastic tenting. In FIG. 42, from point 0 to point A,
the lancet 183 is being accelerated from the initialization
position or zero position. From point A to point B, the lancet is
in ballistic or coasting mode, with no additional power being
delivered. At point B, the lancet tip 196 contacts the tissue 233
and begins to tent the skin 233 until it reaches a displacement C.
As the lancet tip 196 approaches maximum displacement, braking
force is applied to the lancet 183 until the lancet comes to a stop
at point D. The lancet 183 then recoils in a retrograde direction
during the settling phase of the lancing cycle indicated between D
and E. Note that the magnitude of inelastic tenting indicated in
FIG. 42 is exaggerated for purposes of illustration.
[0200] The amount of inelastic tenting indicated by Z tends to be
fairly consistent and small compared to the magnitude of the
elastic tenting. Generally, the amount of inelastic tenting Z can
be about 120 to about 140 microns. As the magnitude of the
inelastic tenting has a fairly constant value and is small compared
to the magnitude of the elastic tenting for most patients and skin
types, the value for the total amount of tenting for the
penetration stroke of the lancet 183 is effectively equal to the
rearward displacement of the lancet during the settling phase as
measured by the processor 193 plus a predetermined value for the
inelastic recoil, such as 130 microns. Inelastic recoil for some
embodiments can be about 100 to about 200 microns. The ability to
measure the magnitude of skin 233 tenting for a patient is
important to controlling the depth of penetration of the lancet tip
196 as the skin is generally known to vary in elasticity and other
parameters due to age, time of day, level of hydration, gender and
pathological state.
[0201] This value for total tenting for the lancing cycle can then
be used to determine the various characteristics of the patient's
skin 233. Once a body of tenting data is obtained for a given
patient, this data can be analyzed in order to predict the total
lancet displacement, from the point of skin contact, necessary for
a successful lancing procedure. This enables the tissue penetration
device to achieve a high success rate and minimize pain for the
user. A rolling average table can be used to collect and store the
tenting data for a patient with a pointer to the last entry in the
table. When a new entry is input, it can replace the entry at the
pointer and the pointer advances to the next value. When an average
is desired, all the values are added and the sum divided by the
total number of entries by the processor 193. Similar techniques
involving exponential decay (multiply by 0.95, add 0.05 times
current value, etc.) are also possible.
[0202] With regard to tenting of skin 233 generally, some typical
values relating to penetration depth are now discussed. FIG. 43
shows a cross sectional view of the layers of the skin 233. In
order to reliably obtain a useable sample of blood from the skin
233, it is desirable to have the lancet tip 196 reach the venuolar
plexus of the skin. The stratum corneum is typically about 0.1 to
about 0.6 mm thick and the distance from the top of the dermis to
the venuole plexus can be from about 0.3 to about 1.4 mm. Elastic
tenting can have a magnitude of up to about 2 mm or so,
specifially, about 0.2 to about 2.0 mm, with an average magnitude
of about 1 mm. This means that the amount of lancet displacement
necessary to overcome the tenting can have a magnitude greater than
the thickness of skin necessary to penetrate in order to reach the
venuolar plexus. The total lancet displacement from point of
initial skin contact may have an average value of about 1.7 to
about 2.1 mm. In some embodiments, penetration depth and maximum
penetration depth may be about 0.5 mm to about 5 mm, specifically,
about 1 mm to about 3 mm. In some embodiments, a maximum
penetration depth of about 0.5 to about 3 mm is useful.
[0203] Referring back to FIG. 29C, in the next operation,
represented by the flow diagram box numbered 280 in FIG. 29C, the
processor 193 causes a withdraw force to be exerted on the lancet
183 to retract the lancet 183 from the skin 233, as shown by arrow
290 in FIG. 36 The processor 193 sends a current to an appropriate
coil 214-217 so that the coil 214-217 exerts an attractive distally
oriented force on the magnetic member 202, which should cause the
lancet 183 to move backward in the desired direction. In some
embodiments, the lancet 183 is withdrawn with less force and a
lower speed than the force and speed during the penetration portion
of the operation cycle. Withdrawal speed of the lancet in some
embodiments can be about 0.004 to about 0.5 m/s, specifically,
about 0.006 to about 0.01 m/s. In other embodiments, useful
withdrawal velocities can be about 0.001 to about 0.02 meters per
second, specifically, about 0.001 to about 0.01 meters per second.
For embodiments that use a relatively slow withdrawal velocity
compared to the penetration velocity, the withdrawal velocity may
up to about 0.02 meters per second. For such embodiments, a ratio
of the average penetration velocity relative to the average
withdrawal velocity can be about 100 to about 1000. In embodiments
where a relatively slow withdrawal velocity is not important, a
withdrawal velocity of about 2 to about 10 meters per second may be
used.
[0204] In the next operation, the processor 193 determines whether
the lancet 183 is moving in the desired backward direction as a
result of the force applied, as represented by the decision box
numbered 281. If the processor 193 determines that the lancet 183
is not moving (a "No" result from the decision box 281), then the
processor 193 continues to cause a force to be exerted on the
lancet 183, as represented by the flow diagram box numbered 282.
The processor 193 may cause a stronger force to be exerted on the
lancet 183 or may just continue to apply the same amount of force.
The processor then again determines whether the lancet is moving,
as represented by the decision box numbered 283. If movement is
still not detected (a "No" result from the decision box numbered
283), the processor 193 determines that an error condition is
present, as represented by the flow diagram box numbered 284. In
such a situation, the processor preferably de-energizes the coils
to remove force from the lancet, as the lack of movement may be an
indication that the lancet is stuck in the skin of the patient and,
therefore, that it may be undesirable to continue to attempt pull
the lancet out of the skin.
[0205] With reference again to the decision boxes numbered 281 and
283 in FIG. 29C, if the processor 193 determines that the lancet is
indeed moving in the desired backward direction away from the skin
233, then the process proceeds to the operation represented by the
flow diagram box numbered 285. In this operation, the backward
movement of the lancet 183 continues until the lancet distal end
has been completely withdrawn from the patient's skin 233. As
discussed above, in some embodiments the lancet 183 is withdrawn
with less force and a lower speed than the force and speed during
the penetration portion of the operation cycle. The relatively slow
withdrawal of the lancet 183 may allow the blood from the
capillaries of the patient accessed by the lancet 183 to follow the
lancet 183 during withdrawal and reach the skin surface to reliably
produce a usable blood sample. The process then ends.
[0206] Controlling the lancet motion over the operating cycle of
the lancet 183 as discussed above allows a wide variety of lancet
velocity profiles to be generated by the lancing device 180. In
particular, any of the lancet velocity profiles discussed above
with regard to other embodiments can be achieved with the processor
193, position sensor 191 and driver coil pack 188 of the lancing
device 180.
[0207] Another example of an embodiment of a velocity profile for a
lancet can be seen in FIGS. 44 and 45, which illustrates a lancet
profile with a fast entry velocity and a slow withdrawal velocity.
FIG. 44 illustrates an embodiment of a lancing profile showing
velocity of the lancet versus position. The lancing profile starts
at zero time and position and shows acceleration of the lancet
towards the tissue from the electromagnetic force generated from
the electromagnetic driver. At point A, the power is shut off and
the lancet 183 begins to coast until it reaches the skin 233
indicated by B at which point, the velocity begins to decrease. At
point C, the lancet 183 has reached maximum displacement and
settles momentarily, typically for a time of about 8
milliseconds.
[0208] A retrograde withdrawal force is then imposed on the lancet
by the controllable driver, which is controlled by the processor to
maintain a withdrawal velocity of no more than about 0.006 to about
0.01 meters/second. The same cycle is illustrated in the velocity
versus time plot of FIG. 45 where the lancet is accelerated from
the start point to point A. The lancet 183 coasts from A to B where
the lancet tip 196 contacts tissue 233. The lancet tip 196 then
penetrates the tissue and slows with braking force eventually
applied as the maximum penetration depth is approached. The lancet
is stopped and settling between C and D. At D, the withdrawal phase
begins and the lancet 183 is slowly withdrawn until it returns to
the initialization point shown by E in FIG. 45. Note that
retrograde recoil from elastic and inelastic tenting was not shown
in the lancing profiles of FIGS. 44 and 45 for purpose of
illustration and clarity.
[0209] In another embodiment, the withdrawal phase may use a dual
speed profile, with the slow 0.006 to 0.01 meter per second speed
used until the lancet is withdrawn past the contact point with the
tissue, then a faster speed of 0.01 to 1 meters per second may be
used to shorten the complete cycle.
[0210] Referring to FIG. 46, another embodiment of a lancing device
including a controllable driver 294 with a driver coil pack 295,
position sensor and lancet 183 are shown. The lancet 297 has a
proximal end 298 and a distal end 299 with a sharpened point at the
distal end 299 of the lancet 297. A magnetic member 301 disposed
about and secured to a proximal end portion 302 of the lancet 297
with a lancet shaft 303 being disposed between the magnetic member
301 and the sharpened point 299. The lancet shaft 303 may be
comprised of stainless steel, or any other suitable material or
alloy. The lancet shaft 303 may have a length of about 3 mm to
about 50 mm specifically, about 5 mm to about 15 mm.
[0211] The magnetic member 301 is configured to slide within an
axial lumen 304 of the driver coil pack 295. The driver coil pack
295 includes a most distal first coil 305, a second coil 306, which
is axially disposed between the first coil 305 and a third coil
307, and a proximal-most fourth coil 308. Each of the first coil
305, second coil 306, third coil 307 and fourth coil 308 has an
axial lumen. The axial lumens of the first through fourth coils
305-308 are configured to be coaxial with the axial lumens of the
other coils and together form the axial lumen 309 of the driver
coil pack 295 as a whole. Axially adjacent each of the coils
305-308 is a magnetic disk or washer 310 that augments completion
of the magnetic circuit of the coils 305-308 during a lancing cycle
of the driven coil pack 295. The magnetic washers 310 of the
embodiment of FIG. 46 are made of ferrous steel but could be made
of any other suitable magnetic material, such as iron or ferrite.
The magnetic washers 310 have an outer diameter commensurate with
an outer diameter of the driver coil pack 295 of about 4.0 to about
8.0 mm. The magnetic washers 310 have an axial thickness of about
0.05, to about 0.4 mm, specifically, about 0.15 to about 0.25 mm.
The outer shell 294 of the coil pack is also made of iron or steel
to complete the magnetic path around the coils and between the
washers 310.
[0212] Wrapping or winding an elongate electrical conductor 311
about the axial lumen 309 until a sufficient number of windings
have been achieved forms the coils 305-308. The elongate electrical
conductor 311 is generally an insulated solid copper wire. The
particular materials, dimensions number of coil windings etc. of
the coils 305-308, washers 310 and other components of the driver
coil pack 295 can be the same or similar to the materials,
dimensions number of coil windings etc. of the driver coil pack 188
discussed above.
[0213] Electrical conductors 312 couple the driver coil pack 295
with a processor 313 which can be configured or programmed to
control the current flow in the coils 305-308 of the driver coil
pack 295 based on position feedback from the position sensor 296,
which is coupled to the processor 313 by electrical conductors 315.
A power source 316 is electrically coupled to the processor 313 and
provides electrical power to operate the processor 313 and power
the driver coil pack 295. The power source 316 may be one or more
batteries (not shown) that provide direct current power to the
processor 313 as discussed above.
[0214] The position sensor 296 is an analog reflecting light sensor
that has a light source and light receiver in the form of a photo
transducer 317 disposed within a housing 318 with the housing 318
secured in fixed spatial relation to the driver coil pack 295. A
reflective member 319 is disposed on or secured to a proximal end
320 of the magnetic member 301. The processor 313 determines the
position of the lancet 299 by first emitting light from the light
source of the photo transducer 317 towards the reflective member
319 with a predetermined solid angle of emission. Then, the light
receiver of the photo transducer 317 measures the intensity of
light reflected from the reflective member 319 and electrical
conductors 315 transmit the signal generated therefrom to the
processor 313.
[0215] By calibrating the intensity of reflected light from the
reflective member 319 for various positions of the lancet 297
during the operating cycle of the driver coil pack 295, the
position of the lancet 297 can thereafter be determined by
measuring the intensity of reflected light at any given moment. In
one embodiment, the sensor 296 uses a commercially available
LED/photo transducer module such as the OPB703 manufactured by
Optek Technology, Inc., 1215 W. Crosby Road, Carrollton, Tex.,
75006. This method of analog reflective measurement for position
sensing can be used for any of the embodiments of lancet actuators
discussed herein. In addition, any of the lancet actuators or
drivers that include coils may use one or more of the coils to
determine the position of the lancet 297 by using a magnetically
permeable region on the lancet shaft 303 or magnetic member 301
itself as the core of a Linear Variable Differential Transformer
(LVDT).
[0216] Referring to FIGS. 47 and 48, a flat coil lancet driver 325
is illustrated which has a main body housing 326 and a rotating
frame 327. The rotating frame 327 pivots about an axle 328 disposed
between a base 329, a top body portion 330 of the main body housing
326 and disposed in a pivot guide 331 of the rotating frame 327. An
actuator arm 332 of the rotating frame 327 extends radially from
the pivot guide 331 and has a linkage receiving opening 333
disposed at an outward end 334 of the actuator arm 332. A first end
335 of a coupler linkage 336 is coupled to the linkage receiving
opening 333 of the actuator arm 332 and can rotate within the
linkage receiving opening 333. A second end 337 of the coupler
linkage 336 is disposed within an opening at a proximal end 338 of
a coupler translation member 341. This configuration allows
circumferential forces imposed upon the actuator arm 332 to be
transferred into linear forces on a drive coupler 342 secured to a
distal end 343 of the coupler translation member 341. The materials
and dimensions of the drive coupler 342 can be the same or similar
to the materials and dimensions of the drive coupler 342 discussed
above.
[0217] Opposite the actuator arm 332 of the rotating frame 327, a
translation substrate in the form of a coil arm 344 extends
radially from the pivot guide 331 of the rotating frame 327. The
coil arm 344 is substantially triangular in shape. A flat coil 345
is disposed on and secured to the coil arm 344. The flat coil 345
has leading segment 346 and a trailing segment 347, both of which
extend substantially orthogonal to the direction of motion of the
segments 346 and 347 when the rotating frame 327 is rotating about
the pivot guide 331. The leading segment 346 is disposed within a
first magnetically active region 348 generated by a first upper
permanent magnet 349 secured to an upper magnet base 351 and a
first lower permanent magnet 352 secured to a lower magnet base
353. The trailing segment 347 is disposed within a second
magnetically active region 354 generated by a second upper
permanent magnet 355 secured to the upper magnet base 351 and a
second lower permanent magnet secured to the lower magnet base
353.
[0218] The magnetic field lines or circuit of the first upper and
lower permanent magnets 349, 352, 355 and 356 can be directed
upward from the first lower permanent magnet 352 to the first upper
permanent magnet 349 or downward in an opposite direction. The
magnetic field lines from the second permanent magnets 355 and 356
are also directed up or down, and will have a direction opposite to
that of the first upper and lower permanent magnets 349 and 352.
This configuration produces rotational force on the coil arm 344
about the pivot guide 331 with the direction of the force
determined by the direction of current flow in the flat coil
345.
[0219] A position sensor 357 includes an optical encoder disk
section 358 is secured to the rotating frame 327 which rotates with
the rotating frame 327 and is read by an optical encoder 359 which
is secured to the base 329. The position sensor 357 determines the
rotational position of the rotating frame 327 and sends the
position information to a processor 360 which can have features
which are the same or similar to the features of the processor 193
discussed above via electrical leads 361. Electrical conductor
leads 363 of the flat coil 345 are also electrically coupled to the
processor 360.
[0220] As electrical current is passed through the leading segment
346 and trailing segment 347 of the flat coil 345, the rotational
forces imposed on the segments 346 and 347 are transferred to the
rotating frame 327 to the actuator arm 332, through the coupler
linkage 336 and coupler translation member 341 and eventually to
the drive coupler 342. In use, a lancet (not shown) is secured into
the drive coupler 342, and the flat coil lancet actuator 325
activated. The electrical current in the flat coil 345 determines
the forces generated on the drive coupler 342, and hence, a lancet
secured to the coupler 342. The processor 360 controls the
electrical current in the flat coil 345 based on the position and
velocity of the lancet as measured by the position sensor 357
information sent to the processor 360. The processor 360 is able to
control the velocity of a lancet in a manner similar to the
processor 193 discussed above and can generate any of the desired
lancet velocity profiles discussed above, in addition to
others.
[0221] FIGS. 49 and 50 depict yet another embodiment of a
controlled driver 369 having a driver coil pack 370 for a tissue
penetration device. The driver coil pack 370 has a proximal end
371, a distal end 372 and an axial lumen 373 extending from the
proximal end 371 to the distal end 372. An inner coil 374 is
disposed about the axial lumen 373 and has a tapered configuration
with increasing wraps per inch of an elongate conductor 375 in a
distal direction. The inner coil 374 extends from the proximal end
371 of the coil driver pack 370 to the distal end 372 of the driver
coil pack 370 with a major outer diameter or transverse dimension
of about 1 to about 25 mm, specifically about 1 to about 12 mm.
[0222] The outer diameter or transverse dimension of the inner coil
374 at the proximal end 371 of the driver coil pack 370 is
approximately equal to the diameter of the axial lumen 373 at the
proximal end 371 of the coil pack 370. That is, the inner coil 374
tapers to a reduce outer diameter proximally until there are few or
no wraps of elongate electrical conductor 375 at the proximal end
371 of the driver coil pack 370. The tapered configuration of the
inner coil 374 produces an axial magnetic field gradient within the
axial lumen 373 of the driver coil pack 370 when the inner coil 374
is activated with electrical current flowing through the elongate
electrical conductor 375 of the inner coil 374.
[0223] The axial magnetic field gradient produces a driving force
for a magnetic member 376 disposed within the axial lumen 373 that
drives the magnetic member 376 towards the distal end 372 of the
driver coil pack 370 when the inner coil 374 is activated. The
driving force on the magnetic member produced by the inner coil 374
is a smooth continuous force, which can produce a smooth and
continuous acceleration of the magnetic member 376 and lancet 377
secured thereto. In some embodiments, the ratio of the increase in
outer diameter versus axial displacement along the inner coil 374
in a distal direction can be from about 1 to about 0.08,
specifically, about 1 to about 0.08.
[0224] An outer coil 378 is disposed on and longitudinally
coextensive with the inner coil 374. The outer coil 378 can have
the same or similar dimensions and construction as the inner coil
374, except that the outer coil 378 tapers proximally to an
increased diameter or transverse dimension. The greater wraps per
inch of elongate electrical conductor 379 in a proximal direction
for the outer coil 378 produces a magnetic field gradient that
drives the magnetic member 376 in a proximal direction when the
outer coil 378 is activated with electrical current. This produces
a braking or reversing effect on the magnetic member 376 during an
operational cycle of the lancet 377 and driver coil pack 370. The
elongate electrical conductors 375 and 379 of the inner coil 374
and outer coil 378 are coupled to a processor 381, which is coupled
to an electrical power source 382. The processor 381 can have
properties similar to the other processors discussed above and can
control the velocity profile of the magnetic member 376 and lancet
377 to produce any of the velocity profiles above as well as
others. The driver coil pack 370 can be used as a substitute for
the coil driver pack discussed above, with other components of the
lancing device 180 being the same or similar.
[0225] Embodiments of driver or actuator mechanisms having been
described, we now discuss embodiments of devices which can house
lancets, collect samples of fluids, analyze the samples or any
combination of these functions. These front-end devices may be
integrated with actuators, such as those discussed above, or any
other suitable driver or controllable driver.
[0226] Generally, most known methods of blood sampling require
several steps. First, a measurement session is set up by gathering
various articles such as lancets, lancet drivers, test strips,
analyzing instrument, etc. Second, the patient must assemble the
paraphernalia by loading a sterile lancet, loading a test strip,
and arming the lancet driver. Third, the patient must place a
finger against the lancet driver and using the other hand to
activate the driver. Fourth, the patient must put down the lancet
driver and place the bleeding finger against a test strip, (which
may or may not have been loaded into an analyzing instrument). The
patient must insure blood has been loaded onto the test strip and
the analyzing instrument has been calibrated prior to such loading.
Finally, the patient must dispose of all the blood-contaminated
paraphernalia including the lancet. As such, integrating the
lancing and sample collection features of a tissue penetration
sampling device can achieve advantages with regard to patient
convenience.
[0227] FIG. 51 shows a disposable sampling module 410, which houses
the lancet 412. The lancet 412 has a head on a proximal end 416
which connects to the driver 438 and a distal end 414, which lances
the skin. The distal end 414 is disposed within the conduit 418.
The proximal end 416 extends into the cavity 420. The sample
reservoir 422 has a narrow input port 424 on the ergonomically
contoured surface 426, which is adjacent to the distal end 414 of
the lancet 412. The term ergonomically contoured, as used herein,
generally means shaped to snugly fit a finger or other body portion
to be lanced or otherwise tested placed on the surface. The
sampling module 410 is capable of transporting the blood sample
from the sample reservoir 422 through small passages (not shown),
to an analytical region 428. The analytical region 428 can include
chemical, physical, optical, electrical or other means of analyzing
the blood sample. The lancet, sample flow channel, sample reservoir
and analytical region are integrated into the sampling module 410
in a single packaged unit.
[0228] FIG. 52 shows the chamber 430 in the housing 410' where the
sampling module 410 is loaded. The sampling module 410 is loaded on
a socket 432 suspended with springs 434 and sits in slot 436. A
driver 438 is attached to the socket 432. The driver 438 has a
proximal end 440 and a distal end 442. The driver 438 can be either
a controllable driver or non-controllable driver any mechanical,
such as spring or cam driven, or electrical, such as
electromagnetically or electronically driven, means for advancing,
stopping, and retracting the lancet. There is a clearance 444
between the distal end 442 of the driver 438 and the sensor 446,
which is attached to the chamber 430. The socket 432 also contains
an analyzer 448, which is a system for analyzing blood. The
analyzer 448 corresponds to the analytical region 428 on the module
410 when it is loaded into the socket 432.
[0229] FIG. 53 shows a tissue penetration sampling device 411 with
the sampling module 410 loaded into the socket 432 of housing 410'.
The analytical region 428 and analyzer 448 overlap. The driver 438
fits into the cavity 420. The proximal end 440 of the driver 438
abuts the distal end 416 of the lancet 412. The patient's finger
450 sits on the ergonomically contoured surface 426.
[0230] FIG. 54 shows a drawing of an alternate lancet configuration
where the lancet 412 and driver 438 are oriented to lance the side
of the finger 450 as it sits on the ergonomically contoured surface
426.
[0231] FIG. 55 illustrates the orifice 452 and ergonomically
contoured surface 426. The conduit 418 has an orifice 452, which
opens on a blood well 454. The sample input port 424 of the
reservoir 422 also opens on the blood well 454. The diameter of the
sample input port 424 is significantly greater than the diameter of
the orifice 452, which is substantially the same diameter as the
diameter of the lancet 412. After the lancet is retracted, the
blood flowing from the finger 450 will collect in the blood well
454. The lancet 412 will have been retracted into the orifice 452
effectively blocking the passage of blood down the orifice 452. The
blood will flow from the blood well 454 through the sample input
port 424 into the reservoir 422.
[0232] FIG. 56 shows a drawing of the lancing event. The patient
applies pressure by pushing down with the finger 450 on the
ergonomically contoured surface 426. This applies downward pressure
on the sampling module 410, which is loaded into the socket 432. As
the socket 432 is pushed downward it compresses the springs 434.
The sensor 446 makes contact with the distal end 442 of the driver
438 and thereby electrically detects the presence of the finger on
the ergonomically contoured surface. The sensor can be a
piezoelectric device, which detects this pressure and sends a
signal to circuit 456, which actuates the driver 438 and advances
and then retracts the lancet 412 lancing the finger 450. In another
embodiment, the sensor 446 is an electric contact, which closes a
circuit when it contacts the driver 438 activating the driver 438
to advance and retract the lancet 412 lancing the finger 450.
[0233] An embodiment of a method of sampling includes a reduced
number of steps that must be taken by a patient to obtain a sample
and analysis of the sample. First, the patient loads a sampling
module 410 with an embedded sterile lancet into the housing device
410'. Second, the patient initiates a lancing cycle by turning on
the power to the device or by placing the finger to be lanced on
the ergonomically contoured surface 426 and pressing down.
Initiation of the sensor makes the sensor operational and gives
control to activate the launcher.
[0234] The sensor is unprompted when the lancet is retracted after
its lancing cycle to avoid unintended multiple lancing events. The
lancing cycle consists of arming, advancing, stopping and
retracting the lancet, and collecting the blood sample in the
reservoir. The cycle is complete once the blood sample has been
collected in the reservoir. Third, the patient presses down on the
sampling module, which forces the driver 38 to make contact with
the sensor, and activates the driver 438. The lancet then pierces
the skin and the reservoir collects the blood sample.
[0235] The patient is then optionally informed to remove the finger
by an audible signal such as a buzzer or a beeper, and/or a visual
signal such as an LED or a display screen. The patient can then
dispose of all the contaminated parts by removing the sampling
module 410 and disposing of it. In another embodiment, multiple
sampling modules 410 may be loaded into the housing 410' in the
form of a cartridge (not shown). The patient can be informed by the
tissue penetration sampling device 411 as to when to dispose of the
entire cartridge after the analysis is complete.
[0236] In order to properly analyze a sample in the analytical
region 428 of the sampling module 410, it may be desirable or
necessary to determine whether a fluid sample is present in a given
portion of the sample flow channel, sample reservoir or analytical
area. A variety of devices and methods for determining the presence
of a fluid in a region are discussed below.
[0237] In FIG. 57, a thermal sensor 500 embedded in a substrate 502
adjacent to a surface 504 over which a fluid may flow. The surface
may be, for example, a wall of a channel through which fluid may
flow or a surface of a planar device over which fluid may flow. The
thermal sensor 500 is in electrical communication with a
signal-conditioning element 506, which may be embedded in the
substrate 502 or may be remotely located. The signal-conditioning
element 506 receives the signal from the thermal sensor 500 and
modifies it by means such as amplifying it and filtering it to
reduce noise. FIG. 57 also depicts a thermal sensor 508 located at
an alternate location on the surface where it is directly exposed
to the fluid flow.
[0238] FIG. 58 shows a configuration of a thermal sensor 500
adjacent to a separate heating element 510. The thermal sensor 500
and the heating element 510 are embedded in a substrate 502
adjacent to a surface 504 over which a fluid may flow. In an
alternate embodiment, one or more additional thermal sensors may be
adjacent the heating element and may provide for increased signal
sensitivity. The thermal sensor 500 is in electrical communication
with a signal-conditioning element 506, which may be embedded in
the substrate 502 or may be remotely located.
[0239] The signal-conditioning element 506 receives the signal from
the thermal sensor 500 and modifies it by means such as amplifying
it and filtering it to reduce noise. The heating element 510 is in
electrical communication with a power supply and control element
512, which may be embedded in the substrate 502 or may be remotely
located. The power supply and control element 512 provides a
controlled source of voltage and current to the heating element
510.
[0240] FIG. 59 depicts a configuration of thermal sensors 500
having three thermal sensor/heating element pairs (500/510), or
detector elements, (with associated signal conditioning elements
506 and power supply and control elements 512 as described in FIG.
58) embedded in a substrate 502 near each other alongside a surface
504. The figure depicts the thermal sensors 500 arranged in a
linear fashion parallel to the surface 504, but any operable
configuration may be used. In alternate embodiments, fewer than
three or more than three thermal sensor/heating element pairs
(500/510) may be used to indicate the arrival of fluid flowing
across a surface 504. In other embodiments, self-heating thermal
sensors are used, eliminating the separate heating elements.
[0241] Embodiments of the present invention provide a simple and
accurate methodology for detecting the arrival of a fluid at a
defined location. Such detection can be particularly useful to
define the zero- or start-time of a timing cycle for measuring
rate-based reactions. This can be used in biochemical assays to
detect a variety of analytes present in a variety of types of
biological specimens or fluids and for rate-based reactions such as
enzymatic reactions. Examples of relevant fluids include, blood,
serum, plasma, urine, cerebral spinal fluid, saliva, enzymatic
substances and other related substances and fluids that are well
known in the analytical and biomedical art. The reaction chemistry
for particular assays to analyze biomolecular fluids is generally
well known, and selection of the particular assay used will depend
on the biological fluid of interest.
[0242] Assays that are relevant to embodiments of the present
invention include those that result in the measurement of
individual analytes or enzymes, e.g., glucose, lactate, creatinine
kinase, etc, as well as those that measure a characteristic of the
total sample, for example, clotting time (coagulation) or
complement-dependent lysis. Other embodiments for this invention
provide for sensing of sample addition to a test article or arrival
of the sample at a particular location within that article.
[0243] Referring now to FIG. 60, a substrate 502 defines a channel
520 having an interior surface 522 over which fluid may flow. An
analysis site 524 is located within the channel 520 where fluid
flowing in the channel 520 may contact the analysis site 524. In
various embodiments, the analysis site 524 may alternatively be
upon the interior surface 522, recessed into the substrate 502, or
essentially flush with the interior surface 522. FIG. 60, depicts
several possible locations for thermal sensors relative the
substrate, the channel, and the analysis site; also, other
locations may be useful and will depend upon the design of the
device, as will be apparent to those of skill in art.
[0244] In use, thermal sensors may be omitted from one or more of
the locations depicted in FIG. 60, depending on the intended
design. A recess in the analysis site 524 may provide the location
for a thermal sensor 526, as may the perimeter of the analysis site
provide the location for a thermal sensor 528. One or more thermal
sensors 530, 532, 534 may be located on the upstream side of the
analysis site 524 (as fluid flows from right to left in FIG. 60),
or one or more thermal sensors 536, 538, 540 may be located on the
downstream side of the analysis site 524.
[0245] The thermal sensor may be embedded in the substrate near the
surface, as thermal sensor 542 is depicted. In various other
embodiments, the thermal sensor(s) may be located upon the interior
surface, recessed into the interior surface, or essentially flush
with the interior surface. Each thermal sensor may also be
associated with a signal conditioning element, heating element, and
power supply and control elements, as described above, and a single
signal conditioning element, heating element, or power supply and
control element may be associated with more than one thermal
sensor.
[0246] FIG. 61 shows possible positions for thermal sensors
relative to analysis sites 524 arranged in an array on a surface
556. A recess in the analysis site 524 may provide the location for
a thermal sensor 544, as may the perimeter of the analysis site
provide the location for a thermal sensor 546. The edge of the
surface surrounding the array of analysis sites may provide the
position for one or more thermal sensors 548. Thermal sensors may
be positioned between analysis sites in a particular row 550 or
column 552 of the array, or may be arranged on the diagonal
554.
[0247] In various embodiments, the thermal sensor(s) may be may be
embedded in the substrate near the surface or may be located upon
the surface, recessed into the surface, or essentially flush with
the surface. Each thermal sensor may also be associated with a
signal conditioning elements, heating elements, and power supply
and control elements, as described above, and a single signal
conditioning element, heating element, or power supply and control
element may be associated with more than one thermal sensor.
[0248] The use of small thermal sensors can be useful in
miniaturized systems, such as microfluidic devices, which perform
biomolecular analyses on very small fluid samples. Such analyses
generally include passing a biomolecular fluid through, over, or
adjacent to an analysis site and result in information about the
biomolecular fluid being obtained through the use of reagents
and/or test circuits and/or components associated with the analysis
site.
[0249] FIG. 62 depicts several possible configurations of thermal
sensors relative to channels and analysis sites. The device
schematically depicted in FIG. 62 may be, e.g., a microfluidic
device for analyzing a small volume of a sample fluid, e.g. a
biomolecular fluid. The device has a sample reservoir 560 for
holding a quantity of a sample fluid. The sample fluid is
introduced to the sample reservoir 560 via a sample inlet port 562
in fluid communication with the sample reservoir 560. A thermal
sensor 564 is located in or near the sample inlet port 562. A
primary channel 566 originates at the sample reservoir 560 and
terminates at an outflow reservoir 568.
[0250] One or more supplemental reservoirs 570 are optionally
present and are in fluid communication with the primary channel 566
via one or more supplemental channels 572, which lead from the
supplemental reservoir 570 to the primary channel 566. The
supplemental reservoir 570 functions to hold fluids necessary for
the operation of the assay, such as reagent solutions, wash
solutions, developer solutions, fixative solutions, et cetera. In
the primary channel 566 at a predetermined distance from the sample
reservoir 560, an array of analysis sites 574 is present.
[0251] Thermal sensors are located directly upstream (as fluid
flows from right to left in the figure) from the array 576 and
directly downstream from the array 578. Thermal sensors are also
located in the primary channel adjacent to where the primary
channel originates at the sample reservoir 580 and adjacent to
where the primary channel terminates at the outflow reservoir 582.
The supplemental channel provides the location for another thermal
sensor 584.
[0252] When the device is in operation, the thermal sensor 564
located in or near the sample inlet port 562 is used to indicate
the arrival of the sample fluid, e.g. the biomolecular fluid, in
the local environment of the thermal sensor, as described herein,
and thus provides confirmation that the sample fluid has
successfully been introduced into the device. The thermal sensor
580 located in the primary channel 566 adjacent to where the
primary channel 566 originates at the sample reservoir 560 produces
a signal indicating that sample fluid has started to flow from the
sample reservoir 560 into the primary channel 566. The thermal
sensors 576 in the primary channel 566 just upstream from the array
of analysis sites 574 may be used to indicate that the fluid sample
is approaching the array 574. Similarly, the thermal sensors 578 in
the primary channel 566 just downstream from the array of analysis
sites 574 may be used to indicate that the fluid sample has
advanced beyond the array 574 and has thus contacted each analysis
site.
[0253] The thermal sensor 584 in the supplemental channel 572
provides confirmation that the fluid contained within the
supplemental reservoir 570 has commenced to flow therefrom. The
thermal sensor 582 in the primary channel 566 adjacent to where the
primary channel 566 terminates at the outflow reservoir 568
indicates when sample fluid arrives near the outflow reservoir 568,
which may then indicate that sufficient sample fluid has passed
over the array of analysis sites 574 and that the analysis at the
analysis sites is completed.
[0254] Embodiments of the invention provide for the use of a
thermal sensor to detect the arrival of the fluid sample at a
determined region, such as an analysis site, in the local
environment of the thermal sensor near the thermal sensor. A
variety of thermal sensors may be used. Thermistors are
thermally-sensitive resistors whose prime function is to detect a
predictable and precise change in electrical resistance when
subjected to a corresponding change in temperature Negative
Temperature Coefficient (NTC) thermistors exhibit a decrease in
electrical resistance when subjected to an increase in temperature
and Positive Temperature Coefficient (PTC) thermistors exhibit an
increase in electrical resistance when subjected to an increase in
temperature.
[0255] A variety of thermistors have been manufactured for over the
counter use and application. Thermistors are capable of operating
over the temperature range of -100 degrees to over 600 degrees
Fahrenheit. Because of their flexibility, thermistors are useful
for application to micro-fluidics and temperature measurement and
control.
[0256] A change in temperature results in a corresponding change in
the electrical resistance of the thermistor. This temperature
change results from either an external transfer of heat via
conduction or radiation from the sample or surrounding environment
to the thermistor, or as an internal application of heat due to
electrical power dissipation within the device. When a thermistor
is operated in "self-heating" mode, the power dissipated in the
device is sufficient to raise its temperature above the temperature
of the local environment, which in turn more easily detects thermal
changes in the conductivity of the local environment.
[0257] Thermistors are frequently used in "self heating" mode in
applications such as fluid level detection, airflow detection and
thermal conductivity materials characterization. This mode is
particularly useful in fluid sensing, since a self-heating
conductivity sensor dissipates significantly more heat in a fluid
or in a moving air stream than it does in still air.
[0258] Embodiments of the invention may be designed such that the
thermal sensor is exposed directly to the sample. However, it may
also be embedded in the material of the device, e.g., in the wall
of a channel meant to transport the sample. The thermal sensor may
be covered with a thin coating of polymer or other protective
material.
[0259] Embodiments of the device need to establish a baseline or
threshold value of a monitored parameter such as temperature.
Ideally this is established during the setup process. Once fluid
movement has been initiated, the device continuously monitors for a
significant change thereafter. The change level designated as
"significant" is designed as a compromise between noise rejection
and adequate sensitivity. The actual definition of the "zero- or
start-time" may also include an algorithm determined from the time
history of the data, i.e., it can be defined ranging from the exact
instant that a simple threshold is crossed, to a complex
mathematical function based upon a time sequence of data.
[0260] In use, a signal is read from a thermal sensor in the
absence of the sample or fluid. The fluid sample is then
introduced. The sample flows to or past the site of interest in the
local environment of the thermal sensor, and the thermal sensor
registers the arrival of the sample. The site of interest may
include an analysis site for conducting, e.g., an enzymatic assay.
Measuring the arrival of fluid at the site of interest thus
indicates the zero- or start-time of the reaction to be performed.
For detection of fluid presence, these sites may be any of a
variety of desired locations along the fluidic pathway. Embodiments
of the invention are particularly well suited to a microfluidic
cartridge or platform, which provide the user with an assurance
that a fluid sample has been introduced and has flowed to the
appropriate locations in the platform.
[0261] A rate-based assay must measure both an initiation time, and
some number of later time points, one of which is the end-point of
the assay. Therefore, baseline or threshold value can be
established, and then continuously monitored for a significant
change thereafter; one such change is the arrival of the fluid
sample that initiates the enzyme reaction. Baseline values are
frequently established during the device setup process. The
threshold is designed as a compromise between noise rejection and
adequate sensitivity. The defined zero- or "start-time" can be
defined ranging from the exact instant that a simple threshold is
crossed, to the value algorithmically determined using a filter
based on a time sequence of data.
[0262] Embodiments of the invention accomplish this in a variety of
ways. In one embodiment, an initial temperature measurement is made
at a thermal sensor without the sample present. The arrival of a
sample changes causes the thermal sensor to register a new value.
These values are then compared.
[0263] Another embodiment measures the change in thermal properties
(such as thermal conductivity or thermal capacity) in the local
environment of a thermal sensor caused by the arrival of a fluid
sample. In general this is the operating principle of a class of
devices known as "thermal conductivity sensors" or "heat flux
sensors". At least two hardware implementations have been used and
are described above. One implementation utilizes a thermal sensor
in a "self-heating mode." In "self-heating mode," a self-heating
thermal sensor may utilize a positive temperature coefficient
thermistor placed in or near the flow channel, e.g. located in the
wall of the flow channel.
[0264] An electrical current is run through the thermistor, causing
the average temperature of the thermistor to rise above that of the
surrounding environment. The temperature can be determined from the
electrical resistance, since it is temperature dependent. When
fluid flows through the channel, it changes the local thermal
conductivity near the thermistor (usually to become higher) and
this causes a change in the average temperature of the thermistor.
It also changes the thermal capacity, which modifies the thermal
dynamic response. These changes give rise to a signal, which can be
detected electronically by well-known means, and the arrival of the
fluid can thereby be inferred.
[0265] A second hardware implementation requires a separate heating
element in or near the flow channel, plus a thermal sensor
arrangement in close proximity. Passing a current through the
element provides heat to the local environment and establishes a
local temperature detected by the thermocouple device. This
temperature or its dynamic response is altered by the arrival of
the fluid or blood in or near the local environment, similar to the
previously described implementation, and the event is detected
electronically.
[0266] The heating element can be operated in a controlled input
mode, which may include controlling one or more of the following
parameters--applied current, voltage or power--in a prescribed
manner. When operating in controlled input mode, fluctuations of
the temperature of the thermal sensor are monitored in order to
detect the arrival of the fluid.
[0267] Alternatively, the heating element can be operated in such a
fashion as to control the temperature of the thermal sensor in a
prescribed manner. In this mode of operation, the resulting
fluctuations in one or more of the input parameters to the heating
element (applied current, voltage, and power) can be monitored in
order to detect the arrival of the fluid.
[0268] In either of the above-described operating modes, the
prescribed parameter can be held to a constant value or sequence of
values that are held constant during specific phases of operation
of the device. The prescribed parameter can also varied as a known
function or waveform in time.
[0269] The change in the monitored parameters caused by the arrival
of the fluid can be calculated in any of a number of ways, using
methods well known in the art of signal processing. The signal
processing methods allow the relation of the signal received prior
to arrival of the fluid with the signal received upon arrival of
the fluid to indicate that the fluid has arrived. For example, and
after suitable signal filtering is applied, changes in the
monitored value or the rate of change of the value of the signal
can be monitored to detect the arrival of the fluid. Additionally,
the arrival of fluid will cause a dynamic change in the
thermodynamic properties of the local environment, such as thermal
conductivity or thermal capacity. When the input parameter is a
time varying function this change of thermodynamic properties will
cause a phase shift of the measured parameter relative to the
controlled parameter. This phase shift can be monitored to detect
the arrival of the fluid.
[0270] It should also be noted that sensitivity to thermal noise
and operating power levels could be reduced in these either of
these modes of operation by a suitable choice of time-varying
waveforms for the prescribed parameter, together with appropriate
and well-known signal processing methods applied to the monitored
parameters. However, these potential benefits may come at the cost
of slower response time.
[0271] Referring to FIG. 63, an alternative embodiment of a tissue
penetration sampling device is shown which incorporates disposable
sampling module 590, a lancet driver 591, and an optional module
cartridge 592 are shown. The optional module cartridge comprises a
case body 593 having a storage cavity 594 for storing sampling
modules 590. A cover to this cavity has been left out for clarity.
The cartridge further comprises a chamber 595 for holding the
lancet driver 591. The lancet driver has a preload adjustment knob
596, by which the trigger point of the lancet driver may be
adjusted. This insures a reproducible tension on the surface of the
skin for better control of the depth of penetration and blood
yield. In one embodiment, the sampling module 590 is removably
attached to the lancet driver 591, as shown, so that the sampling
module 590 is disposable and the lancet driver 591 is reusable. In
an alternative embodiment, the sampling module and lancet driver
are contained within a single combined housing, and the combination
sample acquisition module/lancet driver is disposable. The sampling
module 590 includes a sampling site 597, preferably having a
concave depression 598, or cradle, that can be ergonomically
designed to conform to the shape of a user's finger or other
anatomical feature (not shown).
[0272] The sampling site further includes an opening 599 located in
the concave depression. The lancet driver 591 is used to fire a
lancet contained within and guided by the sampling module 590 to
create an incision on the user's finger when the finger is placed
on the sampling site 597. In one embodiment, the sampling site
forms a substantially airtight seal at the opening when the skin is
firmly pressed against the sampling site; the sampling site may
additionally have a soft, compressible material surrounding the
opening to further limit contamination of the blood sample by
ambient air. "Substantially airtight" in this context means that
only a negligible amount of ambient air may leak past the seal
under ordinary operating conditions, the substantially airtight
seal allowing the blood to be collected seamlessly.
[0273] Referring to FIGS. 64 and 65, the lancet 600 is protected in
the integrated housing 601 that provides a cradle 602 for
positioning the user's finger or other body part, a sampling port
603 within the cradle 602, and a sample reservoir 603' for
collecting the resulting blood sample. The lancet 600 is a shaft
with a distal end 604 sharpened to produce the incision with
minimal pain. The lancet 600 further has an enlarged proximal end
605 opposite the distal end. Similar lancets are commonly known in
the art.
[0274] Rather than being limited to a shaft having a sharp end, the
lancet may have a variety of configurations known in the art, with
suitable modifications being made to the system to accommodate such
other lancet configurations, such configurations having a sharp
instrument that exits the sampling port to create a wound from
which a blood sample may be obtained.
[0275] In the figures, the lancet 600 is slidably disposed within a
lancet guide 606 in the housing 601, and movement of the lancet 600
within the lancet guide 606 is closely controlled to reduce lateral
motion of the lancet, thereby reducing the pain of the lance stick.
The sample acquisition module also includes a return stop 613,
which retains the lancet within the sample acquisition module. The
sampling module has an attachment site 615 for attachment to the
lancet driver.
[0276] The sampling module further includes a depth selector
allowing the user to select one of several penetration depth
settings. The depth selector is shown as a multi-position
thumbwheel 607 having a graduated surface. By rotating the
thumbwheel 607, the user selects which part of the graduated
surface contacts the enlarged proximal end 605 of the lancet to
limit the movement of the lancet 600 within the lancet guide
606.
[0277] The thumbwheel is maintained in the selected position by a
retainer 608 having a protruding, rounded surface which engages at
least one of several depressions 609 (e.g. dimples, grooves, or
slots) in the thumbwheel 607. The depressions 609 are spatially
aligned to correspond with the graduated slope of the thumbwheel
607, so that, when the thumbwheel 607 is turned, the depth setting
is selected and maintained by the retainer 608 engaging the
depression 609 corresponding to the particular depth setting
selected.
[0278] In alternate embodiments, the retainer may be located on the
depth selector and the depressions corresponding to the depth
setting located on the housing such that retainer may functionally
engage the depressions. Other similar arrangements for maintaining
components in alignment are known in the art and may be used. In
further alternate embodiments, the depth selector may take the form
of a wedge having a graduated slope, which contacts the enlarged
proximal end of the lancet, with the wedge being retained by a
groove in the housing.
[0279] The sample reservoir 603' includes an elongate, rounded
chamber 610 within the housing 601 of the sample acquisition
module. The chamber 610 has a flat or slightly spherical shape,
with at least one side of the chamber 610 being formed by a smooth
polymer, preferably absent of sharp corners. The sample reservoir
603' also includes a sample input port 611 to the chamber 610,
which is in fluid communication with the sampling port 603, and a
vent 612 exiting the chamber.
[0280] A cover (not shown), preferably of clear material such as
plastic, positions the lancet 600 and closes the chamber 603',
forming an opposing side of the chamber 603'. In embodiments where
the cover is clear, the cover may serve as a testing means whereby
the sample may be analyzed in the reservoir via optical sensing
techniques operating through the cover. A clear cover will also aid
in determining by inspection when the sample reservoir is full of
the blood sample.
[0281] FIG. 66 shows a portion of the sampling module illustrating
an alternate embodiment of the sample reservoir. The sample
reservoir has a chamber 616 having a sample input port 617 joining
the chamber 616 to a blood transport capillary channel 618; the
chamber 616 also has a vent 619. The chamber has a first side 620
that has a flat or slightly spherical shape absent of sharp corners
and is formed by a smooth polymer. An elastomeric diaphragm 621 is
attached to the perimeter of the chamber 616 and preferably is
capable of closely fitting to the first side of the chamber
620.
[0282] To control direction of blood flow, the sample reservoir is
provided with a first check valve 622 located at the entrance 617
of the sample reservoir and a second check valve 623 leading to an
exit channel 624 located at the vent 619. Alternately, a single
check valve (at the location 622) may be present controlling both
flow into the chamber 616 via the blood transport capillary channel
618 and flow out of the chamber 616 into an optional alternate exit
channel 625. The sample reservoir has a duct 626 connecting to a
source of variable pressure facilitating movement of the diaphragm
621.
[0283] When the diaphragm 621 is flexed away from the first side of
the chamber 620 (low pressure supplied from the source via duct
626), the first check valve 622 is open and the second check valve
623 is closed, aspiration of the blood sample into the sample
reservoir follows. When the diaphragm 621 is flexed in the
direction of the first side of the chamber 620 (high pressure
supplied from the source via duct 626) with the first check valve
622 closed and the second check valve 623 open, the blood is forced
out of the chamber 616. The direction of movement and actuation
speed of the diaphragm 621 can be controlled by the pressure
source, and therefore the flow of the sample can be accelerated or
decelerated. This feature allows not only reduced damage to the
blood cells but also for the control of the speed by which the
chamber 616 is filled.
[0284] While control of the diaphragm 621 via pneumatic means is
described in this embodiment, mechanical means may alternately be
used. Essentially, this micro diaphragm pump fulfills the
aspiration, storage, and delivery functions. The diaphragm 621 may
be used essentially as a pump to facilitate transfer of the blood
to reach all areas required. Such required areas might be simple
sample storage areas further downstream for assaying or for
exposing the blood to a chemical sensor or other testing means.
Delivery of the blood may be to sites within the sampling module or
to sites outside the sampling module, i.e. a separate analysis
device.
[0285] In an alternate embodiment, a chemical sensor or other
testing means is located within the sampling module, and the blood
is delivered to the chemical sensor or other testing means via a
blood transfer channel in fluid communication with the sample
reservoir. The components of the sampling module may be injection
molded and the diaphragm may be fused or insertion molded as an
integral component.
[0286] FIG. 67 depicts a portion of the disposable sampling module
surrounding the sampling port 627, including a portion of the
sampling site cradle surface 628. The housing of the sampling
module includes a primary sample flow channel 629 that is a
capillary channel connecting the sample input port to the sample
reservoir. The primary sample flow channel 629 includes a primary
channel lumenal surface 630 and a primary channel entrance 631, the
primary channel entrance 631 opening into the sample input port
627. The sampling module may optionally include a supplemental
sample flow channel 632 that is also a capillary channel having a
supplemental channel lumenal surface 633 and a supplemental channel
entrance 634, the supplemental channel entrance 634 opening into
the sample input port 627.
[0287] The primary sample flow channel 629 has a greater
cross-sectional area than the supplemental sample flow channel 632,
preferably by at least a factor of two. Thus, the supplemental
sample flow channel 632 draws fluid faster than the primary sample
flow channel 629. When the first droplet of blood is received into
the sample input port 627, the majority of this droplet is drawn
through the supplemental sample flow channel 632. However, as the
blood continues to flow from the incision into the sample input
port 627, most of this blood is drawn through the primary sample
flow channel 629, since the supplemental sample flow channel 632 is
of limited capacity and is filled or mostly filled with the first
blood droplet. This dual capillary channel configuration is
particularly useful in testing where there is a concern with
contamination of the sample, e.g. with debris from the lancet
strike or (particularly in the case of blood gas testing) with
air.
[0288] In order to improve blood droplet flow, some priming or
wicking of the surface with blood is at times necessary to begin
the capillary flow process. Portions of the surfaces of the sample
input port 627 and the primary and supplemental (if present) sample
flow channels 629, 632 are treated to render those surfaces
hydrophilic. The surface modification may be achieved using
mechanical, chemical, corona, or plasma treatment. Examples of such
coatings and methods are marketed by AST Products (Billerica,
Mass.) and Spire Corporation (Bedford, Mass.).
[0289] However, a complete blanket treatment of the surface could
prove detrimental by causing blood to indiscriminately flow all
over the surface and not preferentially through the capillary
channel(s). This ultimately will result in losses of blood fluid.
The particular surfaces which receive the treatment are selected to
improve flow of blood from an incised finger on the sampling site
cradle surface 628 through the sample input port 627 and at least
one of the sample flow channels 629, 632 to the sample reservoir.
Thus, the treatment process should be masked off and limited only
to the selected surfaces. The masking process of selectively
modifying the sampling surface from hydrophobic to hydrophilic may
be done with mechanical masking techniques such as with metal
shielding, deposited dielectric or conductive films, or electrical
shielding means.
[0290] In some embodiments, the treated surfaces are limited to one
or more of the following: the surface of the sampling port which
lies between the sampling site cradle surface and the primary and
supplemental sample flow channel, the surface immediately adjacent
to the entrances to the primary and/or supplemental sample flow
channels 631, 634 (both within the sample input port and within the
sample flow channel), and the lumenal surface of the primary and/or
supplemental sample flow channels 630, 633.
[0291] Upon exiting the incision blood preferentially moves through
the sample input port 627 into the supplementary sample flow
channel 632 (if present) and into the primary sample flow channel
629 to the sample reservoir, resulting in efficient capture of the
blood. Alternatively, the substrate material may be selected to be
hydrophilic or hydrophobic, and a portion of the surface of the
substrate material may be treated for the opposite
characteristic.
[0292] In an embodiment, FIG. 67 a membrane 635 at the base of the
sample input port 627 is positioned between the retracted sharpened
distal end of the lancet 636 and the entrance to the sample flow
channels 631, 634. The membrane 635 facilitates the blood sample
flow through the sample flow channels 629, 632 by restricting the
blood from flowing into the area 636 surrounding the distal end of
the lancet 637. The blood thus flows preferentially into the sample
reservoir. In an embodiment, the membrane 635 is treated to have a
hydrophobic characteristic. In another embodiment, the membrane 635
is made of polymer-based film 638 that has been coated with a
silicone-based gel 639.
[0293] For example, the membrane structure may comprise a
polymer-based film 638 composed of polyethylene terephthalate, such
as the film sold under the trademark MYLAR. The membrane structure
may further comprise a thin coating of a silicone-based gel 639
such as the gel sold under the trademark SYLGARD on at least one
surface of the film. The usefulness of such a film is its ability
to reseal after the lancet has penetrated it without physically
affecting the lancet's cutting tip and edges. The MYLAR film
provides structural stability while the thin SYLGARD silicone
laminate is flexible enough to retain its form and close over the
hole made in the MYLAR film. Other similar materials fulfilling the
structural stability and flexibility roles may be used in the
manufacture of the membrane in this embodiment.
[0294] The membrane 635 operates to allow the sharpened distal end
of the lancet 637 to pierce the membrane as the sharpened distal
end of the lancet 637 travels into and through the sample input
port 627. In an embodiment, the silicone-based gel 639 of the
membrane 635 automatically seals the cut caused by the piercing
lancet. Therefore, after an incision is made on a finger of a user,
the blood from the incision is prevented from flowing through the
membrane 635, which aids the blood to travel through the primary
sample flow channel 629 to accumulate within the sample reservoir.
Thus the film prevents any blood from flowing into the lancet
device assembly, and blood contamination and loss into the lancet
device mechanism cavity are prevented. Even without the resealing
layer 639, the hydrophobic membrane 635 deters the flow of blood
across the membrane 635, resulting in improved flow through the
primary sample flow channel 629 and reduced or eliminated flow
through the pierced membrane 635.
[0295] FIGS. 68-70 illustrate one implementation of a lancet driver
640 at three different points during the use of the lancet driver.
In this description of the lancet driver, proximal indicates a
position relatively close to the site of attachment of the sampling
module; conversely, distal indicates a position relatively far from
the site of attachment of the sampling module. The lancet driver
has a driver handle body 641 defining a cylindrical well 642 within
which is a preload spring 643. Proximal to the preload spring 643
is a driver sleeve 644, which closely fits within and is slidably
disposed within the well 642. The driver sleeve 644 defines a
cylindrical driver chamber 645 within which is an actuator spring
646. Proximal to the actuator spring 646 is a plunger sleeve 647,
which closely fits within and is slidably disposed within the
driver sleeve 644.
[0296] The driver handle body 641 has a distal end 648 defining a
threaded passage 649 into which a preload screw 650 fits. The
preload screw defines a counterbore 651. The preload screw 650 has
a distal end 652 attached to a preload adjustment knob 653 and a
proximal end 654 defining an aperture 655. The driver sleeve 644
has a distal end 656 attached to a catch fitting 657. The catch
fitting 657 defines a catch hole 658. The driver sleeve 644 has a
proximal end 659 with a sloped ring feature 660 circling the
interior surface of the driver sleeve's proximal end 659.
[0297] The lancet driver includes a plunger stem 660 having a
proximal end 661 and a distal end 662. At its distal end 662, an
enlarged plunger head 663 terminates the plunger stem 660. At its
proximal end 661, the plunger stem 660 is fixed to the plunger tip
667 by adhesively bonding, welding, crimping, or threading into a
hole 665 in the plunger tip 667. A plunger hook 665 is located on
the plunger stem 660 between the plunger head 663 and the plunger
tip 667. The plunger head 663 is slidably disposed within the
counterbore 651 defined by the preload screw 650. The plunger stem
660 extends from the plunger head 663, through the aperture 655
defined by the proximal end 654 of the preload screw, thence
through the hole 658 in the catch fitting 657, to the joint 664 in
the plunger tip 667. For assembly purposes, the plunger base joint
664 may be incorporated into the plunger sleeve 647, and the
plunger stem 660 attached to the plunger base 664 by crimping,
swaging, gluing, welding, or some other means. Note that the lancet
driver 640 could be replaced with any of the controlled
electromagnetic drivers discussed above.
[0298] The operation of the tissue penetration sampling device may
be described as follows, with reference to FIGS. 63-70. In
operation, a fresh sampling module 590 is removed from the storage
cavity 594 and adjusted for the desired depth setting using the
multi-position thumbwheel 607. The sampling module 590 is then
placed onto the end of the lancet driver 591. The preload setting
may be checked, but will not change from cycle to cycle once the
preferred setting is found; if necessary, the preload setting may
be adjusted using the preload adjustment knob 596.
[0299] The combined sampling module and lancet driver assembly is
then pressed against the user's finger (or other selected
anatomical feature) in a smooth motion until the preset trigger
point is reached. The trigger point corresponds to the amount of
preload force that needs to be overcome to actuate the driver to
drive the lancet towards the skin. The preload screw allows the
preload setting to be adjusted by the user such that a consistent,
preset (by the user) amount of preload force is applied to the
sampling site 597 each time a lancing is performed.
[0300] When the motion to press the assembly against the user's
finger is begun (see FIG. 68), the plunger hook 665 engages catch
fitting 657, holding the actuator spring 646 in a cocked position
while the force against the finger builds as the driver sleeve 644
continues to compress the preload spring 643. Eventually (see FIG.
69) the sloped back of the plunger hook 665 slides into the hole
655 in the proximal end of the preload screw 654 and disengages
from the catch fitting 657. The plunger sleeve 647 is free to move
in a proximal direction once the plunger hook 665 releases, and the
plunger sleeve 647 is accelerated by the actuator spring 646 until
the plunger tip 667 strikes the enlarged proximal end of the lancet
212.
[0301] Upon striking the enlarged proximal end of the lancet 605,
the plunger tip 667 of the actuated lancet driver reversibly
engages the enlarged proximal end of the lancet 605. This may be
accomplished by mechanical means, e.g. a fitting attached to the
plunger tip 667 that detachably engages a complementary fitting on
the enlarged proximal end of the lancet 605, or the enlarged
proximal end of the lancet 605 may be coated with an adhesive that
adheres to the plunger tip 667 of the actuated lancet driver. Upon
being engaged by the plunger tip 667, the lancet 600 slides within
the lancet guide 606 with the sharpened distal end of the lancet
604 emerging from the housing 601 through the sampling port 603 to
create the incision in the user's finger.
[0302] At approximately the point where the plunger tip 667
contacts the enlarged proximal end of the lancet 605, the actuator
spring 646 is at its relaxed position, and the plunger tip 667 is
traveling at its maximum velocity. During the extension stroke, the
actuator spring 646 is being extended and is slowing the plunger
tip 667 and lancet 600. The end of stroke occurs (see FIG. 70) when
the enlarged proximal end of the lancet 605 strikes the
multi-position thumbwheel 607.
[0303] The direction of movement of the lancet 600 is then reversed
and the extended actuator spring then quickly retracts the
sharpened distal end of the lancet 604 back through the sampling
port 603. At the end of the return stroke, the lancet 600 is
stripped from the plunger tip 667 by the return stop 613. The
adhesive adheres to the return stop 613 retaining the lancet in a
safe position.
[0304] As blood seeps from the wound, it fills the sample input
port 603 and is drawn by capillary action into the sample reservoir
603'. In this embodiment, there is no reduced pressure or vacuum at
the wound, i.e. the wound is at ambient air pressure, although
embodiments which draw the blood sample by suction, e.g. supplied
by a syringe or pump, may be used. The vent 612 allows the
capillary action to proceed until the entire chamber is filled, and
provides a transfer port for analysis of the blood by other
instrumentation. The finger is held against the sample acquisition
module until a complete sample is observed in the sample
reservoir.
[0305] As the sampling module 600 is removed from the lancet driver
591, a latch 614 that is part of the return stop 613 structure
engages a sloped ring feature 660 inside the lancet driver 591. As
the lancet driver 591 is removed from the sampling module 600, the
latch forces the return stop 613 to rotate toward the lancet 600,
bending it to lock it in a safe position, and preventing reuse.
[0306] As the sampling module 600 is removed from the lancet driver
591, the driver sleeve 644 is forced to slide in the driver handle
body 641 by energy stored in the preload spring 643. The driver
sleeve 644, plunger sleeve 647, and actuator spring 646 move
outward together until the plunger head 663 on the plunger stem 660
contacts the bottom of the counterbore 651 at the proximal end of
the preload screw 654. The preload spring 643 continues to move the
driver sleeve 644 outward compressing the actuator spring 646 until
the plunger hook 665 passes through the hole 658 in the catch
fitting 657. Eventually the two springs reach equilibrium and the
plunger sleeve 647 comes to rest in a cocked position.
[0307] After the sampling module 600 is removed from the lancet
driver 591, it may be placed in a separate analysis device to
obtain blood chemistry readings. In a preferred embodiment, the
integrated housing 601 or sample reservoir 603' of the sampling
module 600 contains at least one biosensor, which is powered by
and/or read by the separate analysis device. In another embodiment,
the analysis device performs an optical analysis of the blood
sample directly through the clear plastic cover of the sampling
module. Alternatively, the blood sample may be transferred from the
sampling module into an analysis device for distribution to various
analysis processes.
[0308] Alternate embodiments of the invention offer improved
success rates for sampling, which reduces the needless sacrifice of
a sample storage reservoir or an analysis module due to inadequate
volume fill. Alternate embodiments allow automatic verification
that sufficient blood has been collected before signaling the user
(e.g. by a signal light or an audible beep) that it is okay to
remove the skin from the sampling site. In such alternate
embodiments, one or more additional lancet(s) (denoted backup
lancets) and/or lancet driver(s) (denoted backup lancet drivers)
and/or sample reservoir(s) (denoted backup sample reservoirs) are
present with the "primary" sampling module.
[0309] In one such preferred embodiment, following detection of
inadequate blood sample volume (e.g., by light or electronic
methods), a backup sampling cycle is initiated automatically. The
"backup sampling cycle" includes disconnecting the primary sample
reservoir via a simple valving system, bringing the backup
components online, lancing of the skin, collection of the blood,
and movement of the blood to the backup sample reservoir.
[0310] Blood flows into the backup sample reservoir until the
required volume is obtained. The cycle repeats itself, if
necessary, until the correct volume is obtained. Only then is the
sample reservoir made available as a source of sampled blood for
use in measurements or for other applications. The series of
reservoirs and/or lancets and/or lancet drivers may easily be
manufactured in the same housing and be transparent to the
user.
[0311] In one embodiment, up to three sample reservoirs (the
primary plus two backup) are present in a single sample acquisition
module, each connected via a capillary channel/valving system to
one or more sampling ports. Another embodiment has four sample
reservoirs (the primary plus three backup) present in a single
sample acquisition module, each connected via a capillary
channel/valving system to one or more sampling ports. With three or
four sample reservoirs, at least an 80% sampling success rate can
be achieved for some embodiments.
[0312] Another embodiment includes a miniaturized version of the
tissue penetration sampling device. Several of the miniature
lancets may be located in a single sampling site, with
corresponding sample flow channels to transfer blood to one or more
reservoirs. The sample flow channels may optionally have valves for
controlling flow of blood. The device may also include one or more
sensors, such as the thermal sensors discussed above, for detecting
the presence of blood, e.g. to determine if a sufficient quantity
of blood has been obtained. In such an embodiment, the disposable
sampling module, the lancet driver, and the optional module
cartridge will have dimensions no larger than about 150 mm long, 60
mm wide, and 25 mm thick.
[0313] In other embodiments, the size of the tissue penetration
sampling device including the disposable sampling module, the
lancet driver, and the optional cartridge will have dimensions no
larger than about 100 mm long, about 50 mm wide, and about 20 mm
thick, and in still other embodiments no larger than about 70 mm
long, about 30 mm wide, and about 10 mm thick. The size of the
tissue penetration sampling device including the disposable
sampling module, the lancet driver, and the optional cartridge will
generally be at least about 10 mm long, about 5 mm wide, and about
2 mm thick.
[0314] In another miniature embodiment, the dimensions of the
lancet driver without the cartridge or sampling module are no
larger than about 80 mm long, 10 mm wide, and 10 mm thick, or
specifically no larger than about 50 mm long, 7 mm wide, and 7 mm
thick, or even more specifically no larger than about 15 mm long, 5
mm wide, and 3 mm thick; dimensions of the lancet driver without
the cartridge or sampling module are generally at least about 1 mm
long, 0.1 mm wide, and 0.1 mm thick, or specifically at least about
2 mm long, 0.2 mm wide, and 0.2 mm thick, or more specifically at
least about 4 mm long, 0.4 mm wide, and 0.4 mm thick.
[0315] In yet another miniature embodiment, dimensions of the
miniature sampling module without the lancet driver or cartridge
are no larger than about 15 mm long, about 10 mm wide, and about 10
mm thick, or no larger than about 10 mm long, about 7 mm wide, and
about 7 mm thick, or no larger than about 5 mm long, about 3 mm
wide, and about 2 mm thick; dimensions of the miniature sampling
module without the lancet driver or cartridge are generally at
least about 1 mm long, 0.1 mm wide, and 0.1 mm thick, specifically
at least about 2 mm long, 0.2 mm wide, and 0.2 mm thick, or more
specifically at least about 4 mm long, 0.4 mm wide, and 0.4 mm
thick.
[0316] In another embodiment, the miniaturized sampling module and
the lancet driver form a single unit having a shared housing, and
the combined sample acquisition module/lancet driver unit is
disposable. Such a combined unit is no larger than about 80 mm
long, about 30 mm wide, and about 10 mm thick, specifically no
larger than about 50 mm long, about 20 mm wide, and about 5 mm
thick, more specifically, no larger than about 20 mm long, about 5
mm wide, and about 3 mm thick; the combined unit is generally at
least about 2 mm long, about 0.3 mm wide, and about 0.2 mm thick,
specifically at least about 4 mm long, 0.6 mm wide, and 0.4 mm
thick, more specifically, at least about 8 mm long, 1 mm wide, and
0.8 mm thick.
[0317] Referring to FIG. 71, another embodiment of a tissue
penetration sampling device is shown, incorporating a disposable
sampling module 608 cartridge and analyzer device 669 is shown. The
analyzer device 669 includes a deck 670 having a lid 671 attached
to the deck by hinges along the rear edge of the system 672. A
readout display 673 on the lid 671 functions to give the user
information about the status of the analyzer device 669 and/or the
sampling module cartridge 668, or to give readout of a blood test.
The analyzer device 669 has several function buttons 674 for
controlling function of the analyzer device 669 or for inputting
information into the reader device 669. Alternatively, the reader
device may have a touch-sensitive screen, an optical scanner, or
other input means known in the art.
[0318] An analyzer device with an optical scanner may be
particularly useful in a clinical setting, where patient
information may be recorded using scan codes on patients'
wristbands or files. The analyzer reader device may have a memory,
enabling the analyzer device to store results of many recent tests.
The analyzer device may also have a clock and calendar function,
enabling the results of tests stored in the memory to be time and
date-stamped. A computer interface 675 enables records in memory to
be exported to a computer. The analyzer device 669 has a chamber
located between the deck 670 and the lid 671, which closely
accommodates a sampling module cartridge 668. Raising the lid 671,
allowing a sampling module cartridge 668 to be inserted or removed,
accesses the chamber.
[0319] FIG. 72 is an illustration showing some of the features of
an embodiment of a sampling module cartridge. The sampling module
cartridge 668 has a housing having an orientation sensitive contact
interface for mating with a complementary surface on the analyzer
device. The contact interface functions to align the sampling
module cartridge with the analyzer device, and also allows the
analyzer device to rotate the sampling module cartridge in
preparation for a new sampling event. The contact interface may
take the form of cogs or grooves formed in the housing, which mate
with complementary cogs, or grooves in the chamber of the analyzer
device.
[0320] The sampling module cartridge has a plurality of sampling
sites 678 on the housing, which are shown as slightly concave
depressions near the perimeter of the sampling module cartridge
668. Each sampling site defines an opening 679 contiguous with a
sample input port entering the sampling module. In an alternate
embodiment, the sampling sites and sample input ports are located
on the edge of the sampling module cartridge. Optical windows 680
allow transmission of light into the sampling module cartridge for
the purpose of optically reading test results. Alternatively,
sensor connection points allow transmission of test results to the
analyzer device via electrical contact. Access ports 681, if
present, allow transmission of force or pressure into the sampling
module cartridge from the analyzer device. The access ports may be
useful in conjunction with running a calibration test or combining
reagents with sampled blood or other bodily fluids.
[0321] The described features are arranged around the sampling
module cartridge, and the sampling module cartridge is radially
partitioned into many sampling modules, each sampling module having
the components necessary to perform a single blood sampling and
testing event. A plurality of sampling modules are present on a
sampling module cartridge, generally at least ten sampling modules
are present on a single disposable sampling module cartridge; at
least about 20, or more on some embodiments, and at least about 34
sampling modules are present on one embodiment, allowing the
sampling module cartridge to be maintained in the analyzer device
for about a week before replacing with a new sampling module
cartridge (assuming five sampling and testing events per day for
seven days). With increasing miniaturization, up to about 100, or
more preferably up to about 150, sampling modules may be included
on a single sampling module cartridge, allowing up to a month
between replacements with new sampling module cartridges. It may be
necessary for sampling sites to be located in several concentric
rings around the sampling module cartridge or otherwise packed onto
the housing surface to allow the higher number of sampling modules
on a single sampling module cartridge.
[0322] In other embodiments, the sampling module cartridge may be
any other shape which may conveniently be inserted into a analyzer
device and which are designed to contain multiple sampling modules,
e.g. a square, rectangular, oval, or polygonal shape. Each sampling
module is miniaturized, being generally less than about 6.0 cm long
by about 1.0 cm wide by about 1.0 cm thick, so that thirty five
more or less wedge-shaped sampling modules can fit around a disk
having a radius of about 6.0 cm. In some embodiments, the sampling
modules can be much smaller, e.g. less than about 3.0 cm long by
about 0.5 cm wide by about 0.5 cm thick.
[0323] FIG. 73 depicts, in a highly schematic way, a single
sampling module, positioned within the analyzer device. Of course,
it will occur to the person of ordinary skill in the art that the
various recited components may be physically arranged in various
configurations to yield a functional system. FIG. 73 depicts some
components, which might only be present in alternate embodiments
and are not necessarily all present in any single embodiment. The
sampling module has a sample input port 682, which is contiguous
with an opening 683 defined by a sampling site 684 on the cartridge
housing 685. A lancet 686 having a lancet tip 687 adjacent to the
sample input port 682 is operably maintained within the housing
such that the lancet 686 can move to extend the lancet tip 687
through the sample input port 682 to outside of the sampling module
cartridge.
[0324] The lancet 686 also has a lancet head 688 opposite the
lancet tip. The lancet 686 driven to move by a lancet driver 689,
which is schematically depicted as a coil around the lancet 686.
The lancet driver 689 optionally is included in the sampling module
cartridge as pictured or alternatively is external to the sampling
module cartridge. The sampling module may further include a driver
port 690 defined by the housing adjacent to the lancet head
688--the driver port 690 allows an external lancet driver 691
access to the lancet 686.
[0325] In embodiments where the lancet driver 689 is in the
sampling module cartridge, it may be necessary to have a driver
connection point 694 upon the housing accessible to the analyzer
device. The driver connection point 694 may be a means of
triggering the lancet driver 689 or of supplying motive force to
the lancet driver 689, e.g. an electrical current to an
electromechanical lancet driver. Note that any of the drivers
discussed above, including controllable drivers, electromechanical
drivers, etc., can be substituted for the lancet driver 689
shown.
[0326] In one embodiment a pierceable membrane 692 is present
between the lancet tip 687 and the sample input port 682, sealing
the lancet 686 from any outside contact prior to use. A second
membrane 693 may be present adjacent to the lancet head 688 sealing
the driver port 690. The pierceable membrane 692 and the second
membrane 693 function to isolate the lancet 686 within the lancet
chamber to maintain sterility of the lancet 686 prior to use.
During use the lancet tip 687 and the external lancet driver 691
pierce the pierceable membrane 692 and the second membrane 693, if
present respectively.
[0327] A sample flow channel 695 leads from the sample input port
682 to an analytical region 696. The analytical region 696 is
associated with a sample sensor capable of being read by the
analyzer device. If the sample sensor is optical in nature, the
sample sensor may include optically transparent windows 697 in the
housing above and below the analytical region 696, allowing a light
source in the analyzer device to pass light 698 through the
analytical region. An optical sensor 698', e.g. a CMOS array, is
present in the analyzer device for sensing the light 699 that has
passed through the analytical region 696 and generating a signal to
be analyzed by the analyzer device.
[0328] In a separate embodiment, only one optically transparent
window is present, and the opposing side of the analytical region
is silvered or otherwise reflectively coated to reflect light back
through the analytical region and out the window to be analyzed by
the analyzer device. In an alternate embodiment, the sensor is
electrochemical 700, e.g. an enzyme electrode, and includes a means
of transmitting an electric current from the sampling module
cartridge to the analyzer device, e.g. an electrical contact 701,
or plurality of electrical contacts 701, on the housing accessible
to the analyzer device.
[0329] In one embodiment, the pierceable membrane 692 may be made
of polymer-based film that has been coated with a silicone-based
gel. For example, the membrane structure may comprise a
polymer-based film composed of polyethylene terephthalate, such as
the film sold under the trademark MYLAR.RTM.. The membrane
structure may further comprise a thin coating of a silicone-based
gel such as the gel sold under the trademark SYLGARD.RTM. on at
least one surface of the film.
[0330] The usefulness of such a film is its ability to reseal after
the lancet tip has penetrated it without physically affecting the
lancet's cutting tip and edges. The MYLAR.RTM. film provides
structural stability while the thin SYLGARD.RTM. silicone laminate
is flexible enough to retain its form and close over the hole made
in the MYLAR.RTM. film. Other similar materials fulfilling the
structural stability and flexibility roles may be used in the
manufacture of the pierceable membrane in this embodiment.
[0331] The pierceable membrane 692 operates to allow the lancet tip
687 to pierce the pierceable membrane 692 as the lancet tip 687
travels into and through the sampling port 682. In the described
embodiment, the silicone-based gel of the membrane 692
automatically seals the cut caused by the lancet tip 687.
Therefore, after an incision is made on a finger of a user and the
lancet tip 687 is retracted back through the pierceable membrane
692, the blood from the incision is prevented from flowing through
the pierceable membrane 692, which aids the blood to travel through
the sample flow channel 695 to accumulate within the analytical
region 696.
[0332] Thus the pierceable membrane 692 prevents blood from flowing
into the lancet device assembly, and blood contamination and loss
into the lancet device mechanism cavity are prevented. In yet
another embodiment, used sample input ports are automatically
sealed off before going to the next sample acquisition cycle by a
simple button mechanism. A similar mechanism seals off a sample
input port should sampling be unsuccessful.
[0333] In an alternate embodiment, a calibrant supply reservoir 702
is also present in each sampling module. The calibrant supply
reservoir 702 is filled with a calibrant solution and is in fluid
communication with a calibration chamber 703. The calibration
chamber 703 provides a source of a known signal from the sampling
module cartridge to be used to validate and quantify the test
conducted in the analytical region 696. As such, the configuration
of the calibration chamber 703 closely resembles the analytical
region 696.
[0334] During use, the calibrant solution is forced from the
calibrant supply reservoir 702 into the calibration chamber 703.
The figure depicts a stylized plunger 704 above the calibrant
supply reservoir 702 ready to squeeze the calibrant supply
reservoir 702. In practice, a variety of methods of transporting
small quantities of fluid are known in the art and can be
implemented on the sampling module cartridge. The calibration
chamber 703 is associated with a calibrant testing means.
[0335] FIG. 73 shows two alternate calibrant testing means--optical
windows 697 and an electrochemical sensor 676. In cases where the
sampling module is designed to perform several different tests on
the blood, both optical and electrochemical testing means may be
present. The optical windows 697 allow passage of light 677 from
the analyzer device through the calibration chamber 703, whereupon
the light 703' leaving the calibration chamber 703 passes onto an
optical sensor 698' to result in a signal in the analyzer
device.
[0336] The electrochemical sensor 676 is capable of generating a
signal that is communicated to the analyzer device via, e.g. an
electrical contact 704', which is accessible to a contact probe
702' on the analyzer device that can be extended to contact the
electrical contact 704'. The calibrant solution may be any
solution, which, in combination with the calibrant testing means,
will provide a suitable signal, which will serve as calibration
measurement to the analyzer device. Suitable calibrant solutions
are known in the art, e.g. glucose solutions of known
concentration. The calibration measurement is used to adjust the
results obtained from sample sensor from the analytical region
696.
[0337] To maintain small size in some sampling module cartridge
embodiments, allowing small quantities of sampled blood to be
sufficient, each component of the sampling module must be small,
particularly the sample flow channel and the analytical region. The
sample flow channel can be less than about 0.5 mm in diameter,
specifically less than about 0.3 mm in diameter, more specifically
less than about 0.2 mm in diameter, and even more specifically less
than about 0.1 mm in diameter.
[0338] The sample flow channel may generally be at least about 50
micrometers in diameter. The dimensions of the analytical region
may be less than about 1 mm by about 1 mm by about 1 mm,
specifically less than about 0.6 mm by about 0.6 mm by about 0.4
mm, more specifically less than about 0.4 mm by 0.4 mm by 0.2 mm,
and even more specifically less than about 0.2 mm by about 0.2 mm
by about 0.1 mm. The analytical region can generally be at least
about 100 micrometers by 100 micrometers by 50 micrometers.
[0339] The sampling module cartridge is able to return a valid
testing result with less than about 5 microliters of blood taken
from the skin of a patient, specifically less than about 1
microliter, more specifically less than about 0.4 microliters, and
even more specifically less than about 0.2 microliters. Generally,
at least 0.05 microliters of blood is drawn for a sample.
[0340] The cartridge housing may be made in a plurality of distinct
pieces, which are then assembled to provide the completed housing.
The distinct pieces may be manufactured from a wide range of
substrate materials. Suitable materials for forming the described
apparatus include, but are not limited to, polymeric materials,
ceramics (including aluminum oxide and the like), glass, metals,
composites, and laminates thereof. Polymeric materials are
particularly preferred herein and will typically be organic
polymers that are homopolymers or copolymers, naturally occurring
or synthetic, crosslinked or uncrosslinked.
[0341] It is contemplated that the various components and devices
described herein, such as sampling module cartridges, sampling
modules, housings, etc., may be made from a variety of materials,
including materials such as the following: polycarbonates;
polyesters, including poly (ethylene terephthalate) and
poly(butylene terephthalate); polyamides, (such as nylons);
polyethers, including polyformaldehyde and poly (phenylene
sulfide); polyimides, such as that manufactured under the
trademarks KAPTON (DuPont, Wilmington, Del.) and UPILEX (Ube
Industries, Ltd., Japan); polyolefin compounds, including ABS
polymers, Kel-F copolymers, poly(methyl methacrylate),
poly(styrene-butadiene) copolymers, poly(tetrafluoroethylene),
poly(ethylenevinyl acetate) copolymers, poly(N-vinylcarbazole) and
polystyrene.
[0342] The various components and devices described herein may also
be fabricated from a "composite," i.e., a composition comprised of
unlike materials. The composite may be a block composite, e.g., an
A-B-A block composite, an A-B-C block composite, or the like.
Alternatively, the composite may be a heterogeneous combination of
materials, i.e., in which the materials are distinct from separate
phases, or a homogeneous combination of unlike materials. A
laminate composite with several different bonded layers of
identical or different materials can also be used.
[0343] Other preferred composite substrates include polymer
laminates, polymer-metal laminates, e.g., polymer coated with
copper, a ceramic-in-metal or a polymer-in-metal composite. One
composite material is a polyimide laminate formed from a first
layer of polyimide such as KAPTON polyimide, available from DuPont
(Wilmington, Del.), that has been co-extruded with a second, thin
layer of a thermal adhesive form of polyimide known as KJ.RTM.,
also available from DuPont (Wilmington, Del.).
[0344] Any suitable fabrication method for the various components
and devices described herein can be used, including, but not
limited to, molding and casting techniques, embossing methods,
surface machining techniques, bulk machining techniques, and
stamping methods. Further, injection-molding techniques well known
in the art may be useful in shaping the materials used to produce
sample modules and other components.
[0345] For some embodiments, the first time a new sampling module
cartridge 668 is used, the user removes any outer packaging
material from the sampling module cartridge 668 and opens the lid
671 of the analyzer device 669, exposing the chamber. The sampling
module cartridge 668 is slipped into the chamber and the lid 671
closed. The patient's skin is positioned upon the sampling site 678
and the integrated process of lancing the skin, collecting the
blood sample, and testing the blood sample is initiated, e.g. by
pressing a function button 674 to cause the lancet driver to be
triggered. The patient's skin is maintained in position upon the
sampling site 678, adjacent the sample input port 682, until an
adequate volume of blood has been collected, whereupon the system
may emit a signal (e.g. an audible beep) that the patient's skin
may be lifted from the sampling site 678.
[0346] When the testing of the sample is complete, the analyzer
device 669 automatically reads the results from the sampling module
cartridge 668 and reports the results on the readout display 673.
The analyzer device 669 may also store the result in memory for
later downloading to a computer system. The sampling module
cartridge 668 may then automatically be advanced to bring the next
sampling module inline for the next use. Each successive time the
system is used (optionally until the sampling module cartridge 668
is used up), the patient's skin may be placed upon the sampling
site 678 of the (already installed) sampling module cartridge 668,
thus simplifying the process of blood sampling and testing.
[0347] A method of providing more convenient blood sampling,
wherein a series of blood samples may be collected and tested using
a single disposable sampling module cartridge which is designed to
couple to an analyzer device is described. Embodiments of the
sampling module cartridge include a plurality of sampling modules.
Each sampling module can be adapted to perform a single blood
sampling cycle and is functionally arranged within the sampling
module cartridge to allow a new sampling module to be brought
online after a blood sampling cycle is completed.
[0348] Each blood sampling cycle may include lancing of a patient's
skin, collection of a blood sample, and testing of the blood
sample. The blood sampling cycle may also include reading of
information about the blood sample by the analyzer device, display
and/or storage of test results by the analyzer device, and/or
automatically advancing the sampling module cartridge to bring a
new sampling module online and ready for the next blood sampling
cycle to begin.
[0349] A method embodiment starts with coupling of the sampling
module cartridge and analyzer device and then initiating a blood
sampling cycle. Upon completion of the blood sampling cycle, the
sampling module cartridge is advanced to bring a fresh, unused
sampling module online, ready to perform another blood sampling
cycle. Generally, at least ten sampling modules are present,
allowing the sampling module cartridge to be advanced nine times
after the initial blood sampling cycle.
[0350] In some embodiments, more sampling modules are present and
the sampling module cartridge may be advanced about 19 times, and
about 34 times in some embodiments, allowing about 19 or about 34
blood sampling cycles, respectively, after the initial blood
sampling cycle. After a series of blood sampling cycles has been
performed and substantially all (i.e. more than about 80%) of the
sampling modules have been used, the sampling module cartridge is
decoupled from the analyzer device and discarded, leaving the
analyzer device ready to be coupled with a new sampling module
cartridge.
[0351] Referring to FIGS. 74-76, a tissue penetration sampling
device 180 is shown with the controllable driver 179 of FIG. 20
coupled to a sampling module cartridge 705 and disposed within a
driver housing 706. A ratchet drive mechanism 707 is secured to the
driver housing 706, coupled to the sampling module cartridge 705
and configured to advance a sampling module belt 708 within the
sampling module cartridge 705 so as to allow sequential use of each
sampling module 709 in the sampling module belt 708. The ratchet
drive mechanism 707 has a drive wheel 711 configured to engage the
sampling modules 709 of the sampling module belt 708. The drive
wheel 711 is coupled to an actuation lever 712 that advances the
drive wheel 711 in increments of the width of a single sampling
module 709. A T-slot drive coupler 713 is secured to the elongated
coupler shaft 184.
[0352] A sampling module 709 is loaded and ready for use with the
drive head 198 of the lancet 183 of the sampling module 709 loaded
in the T-slot 714 of the drive coupler 713. A sampling site 715 is
disposed at the distal end 716 of the sampling module 709 disposed
about a lancet exit port 717. The distal end 716 of the sampling
module 709 is exposed in a module window 718, which is an opening
in a cartridge cover 721 of the sampling module cartridge 705. This
allows the distal end 716 of the sampling module 709 loaded for use
to be exposed to avoid contamination of the cartridge cover 721
with blood from the lancing process.
[0353] A reader module 722 is disposed over a distal portion of the
sampling module 709 that is loaded in the drive coupler 713 for use
and has two contact brushes 724 that are configured to align and
make electrical contact with sensor contacts 725 of the sampling
module 709 as shown in FIG. 77. With electrical contact between the
sensor contacts 725 and contact brushes 724, the processor 193 of
the controllable driver 179 can read a signal from an analytical
region 726 of the sampling module 709 after a lancing cycle is
complete and a blood sample enters the analytical region 726 of the
sampling module 709. The contact brushes 724 can have any suitable
configuration that will allow the sampling module belt 708 to pass
laterally beneath the contact brushes 724 and reliably make
electrical contact with the sampling module 709 loaded in the drive
coupler 713 and ready for use. A spring loaded conductive ball
bearing is one example of a contact brush 724 that could be used. A
resilient conductive strip shaped to press against the inside
surface of the flexible polymer sheet 727 along the sensor contact
region 728 of the sampling module 709 is another embodiment of a
contact brush 724.
[0354] The sampling module cartridge 705 has a supply canister 729
and a receptacle canister 730. The unused sampling modules of the
sampling module belt 708 are disposed within the supply canister
729 and the sampling modules of the sampling module belt 708 that
have been used are advanced serially after use into the receptacle
canister 730.
[0355] FIG. 77 is a perspective view of a section of the sampling
module belt 708 shown in the sampling module cartridge 705 in FIG.
74. The sampling module belt 708 has a plurality of sampling
modules 709 connected in series by a sheet of flexible polymer 727.
The sampling module belt 708 shown in FIG. 77 is formed from a
plurality of sampling module body portions 731 that are disposed
laterally adjacent each other and connected and sealed by a single
sheet of flexible polymer 727. The flexible polymer sheet 727 can
optionally have sensor contacts 725, flexible electrical conductors
732, sample sensors 733 or any combination of these elements formed
on the inside surface 734 of the flexible polymer sheet 727. These
electrical, optical or chemical elements can be formed by a variety
of methods including vapor deposition and the like.
[0356] The proximal portion 735 of the flexible polymer sheet 727
has been folded over on itself in order to expose the sensor
contacts 725 to the outside surface of the sampling module 709.
This makes electrical contact between the contact brushes 724 of
the reader module 722 and the sensor contacts 725 easier to
establish as the sampling modules 709 are advanced and loaded into
position with the drive coupler 713 of the controllable driver 179
ready for use. The flexible polymer sheet 727 can be secured to the
sampling module body portion 731 by adhesive bonding, solvent
bonding, ultrasonic thermal bonding or any other suitable
method.
[0357] FIG. 78 shows a perspective view of a single sampling module
709 of the sampling module belt 708 of FIG. 77 during the assembly
phase of the sampling module 709. The proximal portion 735 of the
flexible polymer sheet 727 is being folded over on itself as shown
in order to expose the sensor contacts 725 on the inside surface of
the flexible polymer sheet 727. FIG. 79 is a bottom view of a
section of the flexible polymer sheet 727 of the sampling module
709 of FIG. 78 illustrating the sensor contacts 725, flexible
conductors 732 and sample sensors 733 deposited on the bottom
surface of the flexible polymer sheet 727.
[0358] A lancet 183 is shown disposed within the lancet channel 736
of the sampling module 709 of FIG. 78 as well as within the lancet
channels 736 of the sampling modules 709 of the sampling module
belt 708 of FIG. 77. The lancet 183 has a tip 196 and a shaft
portion 201 and a drive head 198. The shaft portion 201 of the
lancet slides within the lancet channel 736 of the sampling module
709 and the drive head 198 of the lancet 183 has clearance to move
in a proximal and distal direction within the drive head slot 737
of the sampling module 709. Disposed adjacent the drive head slot
737 and at least partially forming the drive head slot are a first
protective strut 737' and a second protective strut 737'' that are
elongated and extend substantially parallel to the lancet 183.
[0359] In one lancet 183 embodiment, the drive head 198 of the
lancet 183 can have a width of about 0.9 to about 1.1 mm. The
thickness of the drive head 198 of the lancet 183 can be about 0.4
to about 0.6 mm. The drive head slot 714 of the sampling module 709
should have a width that allows the drive head 198 to move freely
within the drive head slot 714. The shaft portion 201 of the lancet
183 can have a transverse dimension of about 50 .mu.m to about 1000
.mu.m. Typically, the shaft portion 201 of the lancet 183 has a
round transverse cross section, however, other configurations are
contemplated.
[0360] The sampling module body portions 731 and the sheet of
flexible polymer 727 can both be made of polymethylmethacrylate
(PMMA), or any other suitable polymer, such as those discussed
above. The dimensions of a typical sampling module body portion 731
can be about 14 to about 18 mm in length, about 4 to about 5 mm in
width, and about 1.5 to about 2.5 mm in thickness. In other
embodiments, the length of the sample module body portion can be
about 0.5 to about 2.0 inch and the transverse dimension can be
about 0.1 to about 0.5 inch. The thickness of the flexible polymer
sheet 727 can be about 100 to about 150 microns. The distance
between adjacent sampling modules 709 in the sampling module belt
708 can vary from about 0.1 mm to about 0.3 mm, and in some
embodiments, from about 0.2 to about 0.6.
[0361] FIGS. 80 and 81 show a perspective view of the body portion
731 of the sampling module 709 of FIG. 77 without the flexible
polymer cover sheet 727 or lancet 183 shown for purposes of
illustration. FIG. 81 is an enlarged view of a portion of the body
portion 731 of the sampling module 709 of FIG. 80 illustrating the
sampling site 715, sample input cavity 715', sample input port 741,
sample flow channel 742, analytical region 743, control chamber
744, vent 762, lancet channel 736, lancet channel stopping
structures 747 and 748 and lancet guides 749-751 of the sampling
module 709.
[0362] The lancet channel 736 has a proximal end 752 and a distal
end 753 and includes a series of lancet bearing guide portions
749-751 and sample flow stopping structures 747-748. The lancet
guides 749-751 may be configured to fit closely with the shaft of
the lancet 183 and confine the lancet 183 to substantially axial
movement. At the distal end 753 of the lancet channel 736 the
distal-most lancet guide portion 749 is disposed adjacent the
sample input port 741 and includes at its distal-most extremity,
the lancet exit port 754 which is disposed adjacent the sample
input cavity 715'. The sample input cavity can have a transverse
dimension, depth or both, of about 2 to 5 times the transverse
dimension of the lancet 183, or about 0.2 to about 2 mm,
specically, about 0.4 to about 1.5 mm, and more specifially, about
0.5 to about 1.0 mm. The distal-most lancet guide 749 can have
inner transverse dimensions of about 300 to about 350 microns in
width and about 300 to about 350 microns in depth. Proximal of the
distal-most lancet guide portion 749 is a distal sample flow stop
747 that includes a chamber adjacent the distal-most lancet 749.
The chamber has a transverse dimension that is significantly larger
than the transverse dimension of the distal-most lancet guide 749.
The chamber can have a width of about 600 to about 800 microns, and
a depth of about 400 to about 600 microns and a length of about
2000 to about 2200 microns. The rapid transition of transverse
dimension and cross sectional area between the distal-most lancet
bearing guide 749 and the distal sample flow stop 747 interrupts
the capillary action that draws a fluid sample through the sample
input cavity 715' and into the lancet channel 736.
[0363] A center lancet bearing guide 750 is disposed proximal of
the distal lancet channel stop 747 and can have dimensions similar
to those of the distal-most lancet bearing guide 749. Proximal of
the center lancet guide 750 is a proximal lancet channel stop 748
with a chamber. The dimensions of the proximal lancet channel stop
can be the same or similar to those of the distal lancet channel
stop 747. The proximal lancet channel stop 748 can have a width of
about 600 to about 800 microns, and a depth of about 400 to about
600 microns and a length of about 2800 to about 3000 microns.
Proximal of the proximal lancet channel stop 748 is a proximal
lancet guide 751. The proximal lancet guide 751 can dimensions
similar to those of the other lancet guide 749 and 750 portions
with inner transverse dimensions of about 300 to about 350 microns
in width and about 300 to about 350 microns in depth. Typically,
the transverse dimension of the lancet guides 749-751 are about 10
percent larger than the transverse dimension of the shaft portion
201 of the lancet 183 that the lancet guides 749-751 are configured
to guide.
[0364] A proximal fracturable seal (not shown) can be positioned
between the proximal lancet guide 751 and the shaft portion 201 of
the lancet 183 that seals the chamber of the proximal lancet
channel stop 748 from the outside environment. The fracturable seal
seals the chamber of the proximal lancet channel stop 748 and other
interior portions of the sample chamber from the outside
environment when the sampling module 709 is stored for use. The
fracturable seal remains intact until the lancet 183 is driven
distally during a lancet cycle at which point the seal is broken
and the sterile interior portion of the sample chamber is exposed
and ready to accept input of a liquid sample, such as a sample of
blood. A distal fracturable seal (not shown) can be disposed
between the lancet 183 and the distal-most lancet guide 749 of the
sampling module 709 to seal the distal end 753 of the lancet
channel 736 and sample input port 741 to maintain sterility of the
interior portion of the sampling module 709 until the lancet 183 is
driven forward during a lancing cycle.
[0365] Adjacent the lancet exit port 754 within the sample input
cavity 715' is the sample input port 741 that is configured to
accept a fluid sample that emanates into the sample input cavity
715' from target tissue 233 at a lancing site after a lancing
cycle. The dimensions of the sample input port 741 can a depth of
about 60 to about 70 microns, a width of about 400 to about 600
microns. The sample input cavity can have a transverse dimension of
about 2 to about 5 times the transverse dimension of the lancet
183, or about 400 to about 1000 microns. The sample input cavity
serves to accept a fluid sample as it emanates from lanced tissue
and direct the fluid sample to the sample input port 741 and
thereafter the sample flow channel 742. The sample flow channel 742
is disposed between and in fluid communication with the sample
input port 741 and the analytical region 743. The transverse
dimensions of the sample flow channel 742 can be the same as the
transverse dimensions of the sample input port 741 with a depth of
about 60 to about 70 microns, a width of about 400 to about 600
microns. The length of the sample flow channel 742 can be about 900
to about 1100 microns. Thus, in use, target tissue is disposed on
the sampling site 715 and a lancing cycle initiated. Once the
target tissue 233 has been lanced and the sample begins to flow
therefrom, the sample enters the sample input cavity 715' and then
the sample input port 741. The sample input cavity 715' may be
sized and configured to facilitate sampling success by applying
pressure to a perimeter of target tissue 233 before, during and
after the lancing cycle and hold the wound track open after the
lancing cycle to allow blood or other fluid to flow from the wound
track and into the sample input cavity 715'. From the sample input
port 741, the sample in then drawn by capillary or other forces
through the sample flow channel 742 and into the analytical region
743 and ultimately into the control chamber 744. The control
chamber 744 may be used to provide indirect confirmation of a
complete fill of the analytical region 743 by a sample fluid. If a
fluid sample has been detected in the control chamber 744, this
confirms that the sample has completely filled the analytical
region 743. Thus, sample detectors may be positioned within the
control chamber 744 to confirm filling of the analytical region
743.
[0366] The analytical region 743 is disposed between and in fluid
communication with the sample flow channel 742 and the control
chamber 744. The analytical region 743 can have a depth of about 60
to about 70 microns, a width of about 900 to about 1100 microns and
a length of about 5 to about 6 mm. A typical volume for the
analytical region 743 can be about 380 to about 400 nanoliters. The
control chamber 744 is disposed adjacent to and proximal of the
analytical region 743 and can have a transverse dimension or
diameter of about 900 to about 1100 microns and a depth of about 60
to about 70 microns.
[0367] The control chamber 744 is vented to the chamber of the
proximal lancet channel stop 748 by a vent that is disposed between
and in fluid communication with the control chamber 744 and the
chamber of the proximal lancet channel stop 748. Vent 762 can have
transverse dimensions that are the same or similar to those of the
sample flow channel 742 disposed between the analytical region 743
and the sample input port 741. Any of the interior surfaces of the
sample input port 741, sample flow channels 742 and 762, analytical
region 743, vents 745 or control chamber 744 can be coated with a
coating that promotes capillary action. A hydrophilic coating such
as a detergent is an example of such a coating.
[0368] The analytical region 743 accommodates a blood sample that
travels by capillary action from the sampling site 715 through the
sample input cavity 715' and into the sample input port 741,
through the sample flow channel 742 and into the analytical region
743. The blood can then travel into the control chamber 744. The
control chamber 744 and analytical region 743 are both vented by
the vent 762 that allows gases to escape and prevents bubble
formation and entrapment of a sample in the analytical region 743
and control chamber 744. Note that, in addition to capillary
action, flow of a blood sample into the analytical region 743 can
be facilitated or accomplished by application of vacuum, mechanical
pumping or any other suitable method.
[0369] Once a blood sample is disposed within the analytical region
743, analytical testing can be performed on the sample with the
results transmitted to the processor 193 by electrical conductors
732, optically or by any other suitable method or means. In some
embodiments, it may be desirable to confirm that the blood sample
has filled the analytical region 743 and that an appropriate amount
of sample is present in the chamber in order to carry out the
analysis on the sample.
[0370] Confirmation of sample arrival in either the analytical
region 743 or the control chamber 744 can be achieved visually,
through the flexible polymer sheet 727 which can be transparent.
However, it may be desirable in some embodiments to use a very
small amount of blood sample in order to reduce the pain and
discomfort to the patient during the lancing cycle. For sampling
module 709 embodiments such as described here, having the sample
input cavity 715' and sample input port 741 adjacent the lancet
exit port 754 allows the blood sample to be collected from the
patient's skin 233 without the need for moving the sampling module
709 between the lancing cycle and the sample collection process. As
such, the user does not need to be able to see the sample in order
to have it transferred into the sampling module 709. Because of
this, the position of the sample input cavity 715' and the sample
input port 741 adjacent the lancet exit port 754 allows a very
small amount of sample to be reliably obtained and tested.
[0371] Samples on the order of tens of nanoliters, such as about 10
to about 50 nanoliters can be reliably collected and tested with a
sampling module 709. This size of blood sample is too small to see
and reliably verify visually. Therefore, it is necessary to have
another method to confirm the presence of the blood sample in the
analytical region 743. Sample sensors 733, such as the thermal
sample sensors discussed above can positioned in the analytical
region 743 or control chamber 744 to confirm the arrival of an
appropriate amount of blood sample.
[0372] In addition, optical methods, such as spectroscopic analysis
of the contents of the analytical region 743 or control chamber 744
could be used to confirm arrival of the blood sample. Other methods
such as electrical detection could also be used and these same
detection methods can also be disposed anywhere along the sample
flow path through the sampling module 709 to confirm the position
or progress of the sample (or samples) as it moves along the flow
path as indicated by the arrows 763 in FIG. 81. The detection
methods described above can also be useful for analytical methods
requiring an accurate start time.
[0373] The requirement for having an accurate start time for an
analytical method can in turn require rapid filling of an
analytical region 743 because many analytical processes begin once
the blood sample enters the analytical region 743. If the
analytical region 743 takes too long to fill, the portion of the
blood sample that first enters the analytical region 743 will have
been tested for a longer time that the last portion of the sample
to enter the analytical region 743 which can result in inaccurate
results. Therefore, it may be desirable in these circumstances to
have the blood sample flow first to a reservoir, filling the
reservoir, and then have the sample rapidly flow all at once from
the reservoir into the analytical region 743.
[0374] In one embodiment of the sampling module 709, the analytical
region 743 can have a transverse cross section that is
substantially greater than a transverse cross section of the
control chamber 744. The change in transverse cross section can be
accomplished by restrictions in the lateral transverse dimension of
the control chamber 744 versus the analytical region 743, by step
decreases in the depth of the control chamber 744, or any other
suitable method. Such a step between the analytical region 743 and
the control chamber 744 is shown in FIG. 81. In such an embodiment,
the analytical region 743 can behave as a sample reservoir and the
control chamber 744 as an analytical region that requires rapid or
nearly instantaneous filling in order to have a consistent analysis
start time. The analytical region 743 fills by a flow of sample
from the sample flow channel 742 until the analytical region is
full and the sample reaches the step decrease in chamber depth at
the boundary with the control chamber 744. Once the sample reaches
the step decrease in cross sectional area of the control chamber
744, the sample then rapidly fills the control chamber 744 by
virtue of the enhanced capillary action of the reduced cross
sectional area of the control chamber 744. The rapid filling of the
control chamber allows any analytical process initiated by the
presence of sample to be carried out in the control chamber 744
with a reliable start time for the analytical process for the
entire sample of the control chamber 744.
[0375] Filling by capillary force is passive. It can also be useful
for some types of analytical testing to discard the first portion
of a sample that enters the sampling module 709, such as the case
where there may be interstitial fluid contamination of the first
portion of the sample. Such a contaminated portion of a sample can
be discarded by having a blind channel or reservoir that draws the
sample by capillary action into a side sample flow channel (not
shown) until the side sample flow channel or reservoir in fluid
communication therewith, is full. The remainder of the sample can
then proceed to a sample flow channel adjacent the blind sample
flow channel to the analytical region 743.
[0376] For some types of analytical testing, it may be advantageous
to have multiple analytical regions 743 in a single sampling module
709. In this way multiple iterations of the same type of analysis
could be performed in order to derive some statistical information,
e.g. averages, variation or confirmation of a given test or
multiple tests measuring various different parameters could be
performed in different analytical regions 743 in the same sampling
module 709 filled with a blood sample from a single lancing
cycle.
[0377] FIG. 82 is an enlarged elevational view of a portion of an
alternative embodiment of a sampling module 766 having a plurality
of small volume analytical regions 767. The small volume analytical
regions 767 can have dimensions of about 40 to about 60 microns in
width in both directions and a depth that yields a volume for each
analytical region 767 of about 1 nanoliter to about 100 nanoliters,
specifically about 10 nanoliters to about 50 nanoliters. The array
of small volume analytical regions 767 can be filled by capillary
action through a sample flow channel 768 that branches at a first
branch point 769, a second branch point 770 and a third branch
point 771. Each small volume analytical region 767 can be used to
perform a like analytical test or a variety of different tests can
be performed in the various analytical regions 767.
[0378] For some analytical tests, the analytical regions 767 must
have maintain a very accurate volume, as some of the analytical
tests that can be performed on a blood sample are volume dependent.
Some analytical testing methods detect glucose levels by measuring
the rate or kinetic of glucose consumption. Blood volume required
for these tests is on the order of about 1 to about 3 microliters.
The kinetic analysis is not sensitive to variations in the volume
of the blood sample as it depends on the concentration of glucose
in the relatively large volume sample with the concentration of
glucose remaining essentially constant throughout the analysis.
Because this type of analysis dynamically consumes glucose during
the testing, it is not suitable for use with small samples, e.g.
samples on the order of tens of nanoliters where the consumption of
glucose would alter the concentration of glucose.
[0379] Another analytical method uses coulomb metric measurement of
glucose concentration. This method is accurate if the sample volume
is less than about 1 microliter and the volume of the analytical
region is precisely controlled. The accuracy and the speed of the
method is dependent on the small and precisely known volume of the
analytical region 767 because the rate of the analysis is volume
dependent and large volumes slow the reaction time and negatively
impact the accuracy of the measurement.
[0380] Another analytical method uses an optical fluorescence decay
measurement that allows very small sample volumes to be analyzed.
This method also requires that the volume of the analytical region
767 be precisely controlled. The small volume analytical regions
767 discussed above can meet the criteria of maintaining small
accurately controlled volumes when the small volume analytical
regions 767 are formed using precision manufacturing techniques.
Accurately formed small volume analytical regions 767 can be formed
in materials such as PMMA by methods such as molding and stamping;
Machining and etching, either by chemical or laser processes can
also be used. Vapor deposition and lithography can also be used to
achieve the desired results.
[0381] The sampling modules 709 and 766 discussed above all are
directed to embodiments that both house the lancet 183 and have the
ability to collect and analyze a sample. In some embodiments of a
sampling module, the lancet 183 may be housed and a sample
collected in a sample reservoir without any analytical function. In
such an embodiment, the analysis of the sample in the sample
reservoir may be carried out by transferring the sample from the
reservoir to a separate analyzer. In addition, some modules only
serve to house a lancet 183 without any sample acquisition
capability at all. The body portion 774 of such a lancet module 775
is shown in FIG. 83. The lancet module 775 has an outer structure
similar to that of the sampling modules 709 and 766 discussed
above, and can be made from the same or similar materials.
[0382] A flexible polymer sheet 727 (not shown) can be used to
cover the face of the lancet module 775 and contain the lancet 183
in a lancet channel 776 that extends longitudinally in the lancet
module body portion 774. The flexible sheet of polymer 727 can be
from the same material and have the same dimensions as the flexible
polymer sheet 727 discussed above. Note that the proximal portion
of the flexible polymer sheet 727 need not be folded over on itself
because there are no sensor contacts 725 to expose. The flexible
polymer sheet 727 in such a lancet module 775 serves only to
confine the lancet 183 in the lancet channel 776. The lancet module
775 can be configured in a lancet module belt, similar to the
sampling module belt 708 discussed above with the flexible polymer
sheet 727 acting as the belt. A drive head slot 777 is dispose
proximal of the lancet channel 776.
[0383] With regard to the tissue penetration sampling device 180 of
FIG. 74, use of the device 180 begins with the loading of a
sampling module cartridge 705 into the controllable driver housing
706 so as to couple the cartridge 705 to the controllable driver
housing 706 and engage the sampling module belt 708 with the
ratchet drive 707 and drive coupler 713 of the controllable driver
179. The drive coupler 713 can have a T-slot configuration such as
shown in FIGS. 84 and 85. The distal end of the elongate coupler
shaft 184 is secured to the drive coupler 713 which has a main body
portion 779, a first and second guide ramp 780 and 781 and a T-slot
714 disposed within the main body portion 779. The T-slot 714 is
configured to accept the drive head 198 of the lancet 183. After
the sampling module cartridge 705 is loaded into the controllable
driver housing 706, the sampling module belt 708 is advanced
laterally until the drive head 198 of a lancet 183 of one of the
sampling modules 709 is fed into the drive coupler 713 as shown in
FIGS. 86-88. FIGS. 86-88 also illustrate a lancet crimp device 783
that bends the shaft portion 201 of a used lancet 183 that is
adjacent to the drive coupler 713. This prevents the used lancet
183 from moving out through the module body 731 and being
reused.
[0384] As the sampling modules 709 of the sampling module belt 708
are used sequentially, they are advanced laterally one at a time
into the receptacle canister 730 where they are stored until the
entire sampling module belt 708 is consumed. The receptacle
canister 730 can then be properly disposed of in accordance with
proper techniques for disposal of blood-contaminated waste. The
sampling module cartridge 705 allows the user to perform multiple
testing operations conveniently without being unnecessarily exposed
to blood waste products and need only dispose of one cartridge
after many uses instead of having to dispose of a contaminated
lancet 183 or module 709 after each use.
[0385] FIGS. 89 and 90 illustrate alternative embodiments of
sampling module cartridges. FIG. 89 shows a sampling module
cartridge 784 in a carousel configuration with adjacent sampling
modules 785 connected rigidly and with sensor contacts 786 from the
analytical regions of the various sampling modules 785 disposed
near an inner radius 787 of the carousel. The sampling modules 785
of the sampling module cartridge 784 are advanced through a drive
coupler 713 but in a circular as opposed to a linear fashion.
[0386] FIG. 90 illustrates a block of sampling modules 788 in a
four by eight matrix. The drive head 198 of the lancets 183 of the
sampling modules 789 shown in FIG. 90 are engaged and driven using
a different method from that of the drive coupler 713 discussed
above. The drive heads 198 of the lancets 183 have an adhesive
coating 790 that mates with and secures to the drive coupler 791 of
the lancet driver 179, which can be any of the drivers, including
controllable drivers, discussed above.
[0387] The distal end 792 of the drive coupler 791 contacts and
sticks to the adhesive 790 of proximal surface of the drive head
198 of the lancet 183 during the beginning of the lancet cycle. The
driver coupler 791 pushes the lancet 183 into the target tissue 237
to a desired depth of penetration and stops. The drive coupler 791
then retracts the lancet 183 from the tissue 233 using the adhesive
contact between the proximal surface of the drive head 198 of the
lancet 183 and distal end surface of the drive coupler 791, which
is shaped to mate with the proximal surface.
[0388] At the top of the retraction stroke, a pair of hooked
members 793 which are secured to the sampling module 789 engage the
proximal surface of the drive head 198 and prevent any further
retrograde motion by the drive head 198 and lancet 183. As a
result, the drive coupler 791 breaks the adhesive bond with the
drive head 198 and can then be advanced by an indexing operation to
the next sampling module 789 to be used.
[0389] FIG. 91 is a side view of an alternative embodiment of a
drive coupler 796 having a lateral slot 797 configured to accept
the L-shaped drive head 798 of the lancet 799 that is disposed
within a lancet module 800 and shown with the L-shaped drive head
798 loaded in the lateral slot 797. FIG. 92 is an exploded view of
the drive coupler 796, lancet 799 with L-shaped drive head 798 and
lancet module 800 of FIG. 91. This type of drive coupler 796 and
drive head 798 arrangements could be substituted for the
configuration discussed above with regard to FIGS. 84-88. The
L-shaped embodiment of the drive head 798 may be a less expensive
option for producing a coupling arrangement that allows serial
advancement of a sampling module belt or lancet module belt through
the drive coupler 796 of a lancet driver, such as a controllable
lancet driver 179.
[0390] For some embodiments of multiple lancing devices 180, it may
be desirable to have a high capacity-lancing device that does not
require a lancet module 775 in order to house the lancets 183
stored in a cartridge. Eliminating the lancet modules 775 from a
multiple lancet device 180 allows for a higher capacity cartridge
because the volume of the cartridge is not taken up with the bulk
of multiple modules 775. FIGS. 93-96 illustrate a high capacity
lancet cartridge coupled to a belt advance mechanism 804. The belt
advance mechanism 804 is secured to a controlled driver 179 housing
which contains a controlled electromagnetic driver.
[0391] The lancet cartridge 803 has a supply canister 805 and a
receptacle canister 806. A lancet belt 807 is disposed within the
supply canister 805. The lancet belt 807 contains multiple sterile
lancets 183 with the shaft portion 201 of the lancets 183 disposed
between the adhesive surface 808 of a first carrier tape 809 and
the adhesive surface 810 of a second carrier tape 811 with the
adhesive surfaces 808 and 810 pressed together around the shaft
portion 201 of the lancets 183 to hold them securely in the lancet
belt 807. The lancets 183 have drive heads 198 which are configured
to be laterally engaged with a drive coupler 713, which is secured
to an elongate coupler shaft 184 of the controllable driver
179.
[0392] The belt advance mechanism 804 includes a first cog roller
814 and a second cog roller 815 that have synchronized rotational
motion and are advanced in unison in an incremental indexed motion.
The indexed motion of the first and second cog rollers 814 and 815
advances the lancet belt 807 in units of distance equal to the
distance between the lancets 183 disposed in the lancet belt 807.
The belt advance mechanism 804 also includes a first take-up roller
816 and a second take-up roller 817 that are configured to take up
slack in the first and second carrier tapes 809 and 811
respectively.
[0393] When a lancet belt cartridge 803 is loaded in the belt
advance mechanism 804, a lead portion 818 of the first carrier tape
809 is disposed between a first cog roller 814 and a second cog
roller 815 of the belt advance mechanism 804. The lead portion 818
of the first carrier tape 809 wraps around the outer surface 819 of
the first turning roller 827, and again engages roller 814 with the
cogs 820 of the first cog roller 814 engaged with mating holes 821
in the first carrier tape 809. The lead portion 818 of the first
carrier tape 809 is then secured to a first take-up roller 816. A
lead portion 822 of the second carrier tape 811 is also disposed
between the first cog roller 814 and second cog roller 815 and is
wrapped around an outer surface 823 of the second turning roller
828, and again engages roller 815 with the cogs 826' of the second
cog roller 815 engaged in with mating holes 825 of the second
carrier tape 811. The lead portion 822 of the second carrier tape
811 is thereafter secured to a second take-up roller 817.
[0394] As the first and second cog rollers 814 and 815 are
advanced, the turning rollers 827 and 828 peel the first and second
carrier tapes 809 and 811 apart and expose a lancet 183. The added
length or slack of the portions of the first and second carrier
tapes 809 and 811 produced from the advancement of the first and
second cog rollers 814 and 815 is taken up by the first and second
take-up rollers 816 and 817. As a lancet 183 is peeled out of the
first and second carrier tapes 809 and 811, the exposed lancet 183
is captured by a lancet guide wheel 826' of the belt advance
mechanism 804, shown in FIG. 96, which is synchronized with the
first and second cog rollers 814 and 815. The lancet guide wheel
826' then advances the lancet 183 laterally until the drive head
198 of the lancet 183 is loaded into the drive coupler 713 of the
controllable driver 179. The controllable driver 179 can then be
activated driving the lancet 183 into the target tissue 233 and
retracted to complete the lancing cycle.
[0395] Once the lancing cycle is complete, the belt advance
mechanism 804 can once again be activated which rotates the lancet
guide wheel 826 and advances the used lancet 183 laterally and into
the receptacle canister 806. At the same time, a new unused lancet
183 is loaded into the drive coupler 713 and readied for the next
lancing cycle. This repeating sequential use of the multiple
lancing device 180 continues until all lancets 183 in the lancet
belt 807 have been used and disposed of in the receptacle canister
806. After the last lancet 183 has been consumed, the lancet belt
cartridge 803 can then be removed and disposed of without exposing
the user to any blood contaminated materials. The belt advance
mechanism 804 can be activated by a variety of methods, including a
motorized drive or a manually operated thumbwheel which is coupled
to the first and second cog rollers 814 and 815 and lancet guide
wheel 826.
[0396] Although discussion of the devices described herein has been
directed primarily to substantially painless methods and devices
for access to capillary blood of a patient, there are many other
uses for the devices and methods. For example, the tissue
penetration devices discussed herein could be used for
substantially painless delivery of small amounts of drugs, or other
bioactive agents such as gene therapy agents, vectors, radioactive
sources etc. As such, it is contemplated that the tissue
penetration devices and lancet devices discussed herein could be
used to delivery agents to positions within a patient's body as
well as taking materials from a patient's body such as blood, lymph
fluid, spinal fluid and the like. Drugs delivered may include
analgesics that would further reduce the pain perceived by the
patient upon penetration of the patient's body tissue, as well as
anticoagulants that may facilitate the successful acquisition of a
blood sample upon penetration of the patient's tissue.
[0397] Referring to FIGS. 97-101, a device for injecting a drug or
other useful material into the tissue of a patient is illustrated.
The ability to localize an injection or vaccine to a specific site
within a tissue, layers of tissue or organ within the body can be
important. For example, epithelial tumors can be treated by
injection of antigens, cytokine, or colony stimulating factor by
hypodermic needle or high-pressure injection sufficient for the
antigen to enter at least the epidermis or the dermis of a patient.
Often, the efficacy of a drug or combination drug therapy depends
on targeted delivery to localized areas thus affecting treatment
outcome.
[0398] The ability to accurately deliver drugs or vaccinations to a
specific depth within the skin or tissue layer may avoid wastage of
expensive drug therapies therefore impacting cost effectiveness of
a particular treatment. In addition, the ability to deliver a drug
or other agent to a precise depth can be a clear advantage where
the outcome of treatment depends on precise localized drug delivery
(such as with the treatment of intralesional immunotherapy). Also,
rapid insertion velocity of a hypodermic needle to a precise
predetermined depth in a patient's skin is expected to reduce pain
of insertion of the needle into the skin. Rapid insertion and
penetration depth of a hypodermic needle, or any other suitable
elongated delivery device suitable for penetrating tissue, can be
accurately controlled by virtue of a position feedback loop of a
controllable driver coupled to the hypodermic needle.
[0399] FIG. 97 illustrates 901 distal end 901 of a hypodermic
needle 902 being driven into layers of skin tissue 903 by an
electromagnetic controllable driver 904. The electromagnetic
controllable driver 904 of FIG. 79 can have any suitable
configuration, such as the configuration of electromagnetic
controllable drivers discussed above. The layers of skin 903 being
penetrated include the stratum corneum 905, the stratum lucidum
906, the stratum granulosum 907, the stratum spinosum 908, the
stratum basale 909 and the dermis 911. The thickness of the stratum
corneum 905 is typically about 300 micrometers in thickness. The
portion of the epidermis excluding the stratum corneum 905 includes
the stratum lucidum 906, stratum granulosum 907, and stratum basale
can be about 200 micrometers in thickness. The dermis can be about
1000 micrometers in thickness. In FIG. 97, an outlet port 912 of
the hypodermic needle 902 is shown disposed approximately in the
stratum spinosum 908 layer of the skin 903 injecting an agent 913
into the stratum spinosum 908.
[0400] FIGS. 98-101 illustrate an agent injection module 915
including an injection member 916, that includes a collapsible
canister 917 and the hypodermic needle 902, that may be driven or
actuated by a controllable driver, such as any of the controllable
drivers discussed above, to drive the hypodermic needle into the
skin 903 for injection of drugs, vaccines or the like. The agent
injection module 915 has a reservoir, which can be in the form of
the collapsible canister 917 having a main chamber 918, such as
shown in FIG. 98, for the drug or vaccine 913 to be injected. A
cassette of a plurality of agent injection modules 915 (not shown)
may provide a series of metered doses for long-term medication
needs. Such a cassette may be configured similarly to the module
cassettes discussed above. Agent injection modules 915 and needles
902 may be disposable, avoiding biohazard concerns from unspent
drug or used hypodermic needles 902. The geometry of the cutting
facets 921 of the hypodermic needle shown in FIG. 79, may be the
same or similar to the geometry of the cutting facets of the lancet
183 discussed above.
[0401] Inherent in the position and velocity control system of some
embodiments of a controllable driver is the ability to precisely
determine the position or penetration depth of the hypodermic
needle 902 relative to the controllable driver or layers of target
tissue or skin 903 being penetrated. For embodiments of
controllable drivers that use optical encoders for position
sensors, such as an Agilent HEDS 9200 series, and using a four edge
detection algorithm, it is possible to achieve an in plane spatial
resolution of +/-17 .mu.m in depth. If a total tissue penetration
stroke is about 3 mm in length, such as might be used for
intradermal or subcutaneous injection, a total of 88 position
points can be resolved along the penetration stroke. A spatial
resolution this fine allows precise placement of a distal tip 901
or outlet port 912 of the hypodermic needle 902 with respect to the
layers of the skin 903 during delivery of the agent or drug 913. In
some embodiments, a displacement accuracy of better than about 200
microns can be achieved, in others a displacement accuracy of
better than about 40 microns can be achieved.
[0402] The agent injection module 915 includes the injection member
916 which includes the hypodermic needle 902 and drug reservoir or
collapsible canister 917, which may couple to an elongated coupler
shaft 184 via a drive coupler 185 as shown. The hypodermic needle
902 can be driven to a desired penetration depth, and then the drug
or other agent 913, such as a vaccine, is passed into an inlet port
922 of the needle 902 through a central lumen 923 of the hypodermic
needle 902 as shown by arrow 924, shown in FIG. 98, and out of the
outlet port 912 at the distal end 901 of the hypodermic needle 902,
shown in FIG. 97.
[0403] Drug or agent delivery can occur at the point of maximum
penetration, or following retraction of the hypodermic needle 902.
In some embodiments, it may be desirable to deliver the drug or
agent 913 during insertion of the hypodermic needle 902. Drug or
agent delivery can continue as the hypodermic needle 902 is being
withdrawn (this is commonly the practice during anesthesia in
dental work). Alternatively drug delivery can occur while the
needle 902 is stationary during any part of the retraction
phase.
[0404] The hollow hypodermic needle 902 is fitted with the
collapsible canister 917 containing a drug or other agent 913 to be
dispensed. The walls 928 of this collapsible canister 917 can be
made of a soft resilient material such as plastic, rubber, or any
other suitable material. A distal plate 925 is disposed at the
distal end 926 of the collapsible canister is fixed securely to the
shaft 927 of the hypodermic needle proximal of the distal tip 901
of the hypodermic needle 902. The distal plate 925 is sealed and
secured to the shaft 927 of the hypodermic needle 902 to prevent
leakage of the medication 913 from the collapsible canister
917.
[0405] A proximal plate 931 disposed at a proximal end 932 of the
collapsible canister 917 is slidingly fitted to a proximal portion
933 of the shaft 927 of the hypodermic needle 902 with a sliding
seal 934'. The sliding seal 934 prevents leakage of the agent or
medication 913 between the seal 934 and an outside surface of the
shaft 927 of the hypodermic needle 902. The sliding seal allows the
proximal plate 931 of the collapsible canister 917 to slide axially
along the needle 902 relative to the distal plate 925 of the
collapsible canister 917. A drug dose may be loaded into the main
chamber 918 of the collapsible canister 917 during manufacture, and
the entire assembly protected during shipping and storage by
packaging and guide fins 935 surrounding the drive head slot 936 of
the agent injection module 915.
[0406] An injection cycle may begin when the agent injection module
915 is loaded into a ratchet advance mechanism (not shown), and
registered at a drive position with a drive head 937 of the
hypodermic needle 902 engaged in the drive coupler 185. The
position of the hypodermic needle 902 and collapsible canister 917
in this ready position is shown in FIG. 99.
[0407] Once the drive head 937 of the agent injection module 915 is
loaded into the driver coupler 185, the controllable driver can
then be used to launch the injection member 916 including the
hypodermic needle 902 and collapsible canister 917 towards and into
the patient's tissue 903 at a high velocity to a predetermined
depth into the patient's skin or other organ. The velocity of the
injection member 916 at the point of contact with the patient's
skin 903 or other tissue can be up to about 10 meters per second
for some embodiments, specifically, about 2 to about 5 m/s. In some
embodiments, the velocity of the injection member 916 may be about
2 to about 10 m/s at the point of contact with the patient's skin
903. As the collapsible canister 917 moves with the hypodermic
needle 902, the proximal plate 931 of the collapsible canister 917
passes between two latch springs 938 of module body 939 that snap
in behind the proximal plate 931 when the collapsible canister 917
reaches the end of the penetration stroke, as shown in FIG.
100.
[0408] The controllable driver then reverses, applies force in the
opposite retrograde direction and begins to slowly (relative to the
velocity of the penetration stroke) retract the hypodermic needle
902. The hypodermic needle 902 slides through the sliding seal 934
of the collapsible canister 917 while carrying the distal plate 925
of the collapsible canister with it in a proximal direction
relative to the proximal plate 931 of the collapsible canister 917.
This relative motion between the distal plate 925 of the
collapsible canister 917 and the proximal plate 931 of the
collapsible canister 917 causes the volume of the main chamber 918
to decrease. The decreasing volume of the main chamber 918 forces
the drug or other agent 913 disposed within the main chamber 918 of
the collapsible canister 917 out of the main chamber 918 into the
inlet port 922 in the shaft 927 of the hypodermic needle 902. The
inlet port 922 of the hypodermic needle 902 is disposed within an
in fluid communication with the main chamber 918 of the collapsible
canister 917 as shown in FIG. 80. The drug or agent then passes
through the central lumen 923 of the hollow shaft 927 of the
hypodermic needle 902 and is then dispensed from the output port
912 at the distal end 901 of the hypodermic needle 902 into the
target tissue 903. The rate of perfusion of the drug or other agent
913 may be determined by an inside diameter or transverse dimension
of the collapsible canister 917. The rate of perfusion may also be
determined by the viscosity of the drug or agent 913 being
delivered, the transverse dimension or diameter of the central
lumen 923, the input port 922, or the output port 912 of the
hypodermic needle 902, as well as other parameters.
[0409] During the proximal retrograde retraction stroke of the
hypodermic needle 902, drug delivery continues until the main
chamber 918 of the collapsible canister 917 is fully collapsed as
shown in FIG. 101. At this point, the drive coupler 185 may
continue to be retracted until the drive head 937 of the hypodermic
needle 902 breaks free or the distal seal 941 between the distal
plate 925 of the chamber and the hypodermic needle 902 fails,
allowing the drive coupler 185 to return to a starting position.
The distal tip 901 of the hypodermic needle 902 can be driven to a
precise penetration depth within the tissue 903 of the patient
using any of the methods or devices discussed above with regard to
achieving a desired penetration depth using a controllable driver
or any other suitable driver.
[0410] In another embodiment, the agent injection module 915 is
loaded into a ratchet advance mechanism that includes an adjustable
or movable distal stage or surface (not shown) that positions the
agent injection 915 module relative to a skin contact point or
surface 942. In this way, an agent delivery module 915 having a
penetration stroke of predetermined fixed length, such as shown in
FIGS. 99-101, reaches a pre-settable penetration depth. The movable
stage remains stationary during a drug delivery cycle. In a
variation of this embodiment, the moveable stage motion may be
coordinated with a withdrawal of the hypodermic needle 902 to
further control the depth of drug delivery.
[0411] In another embodiment, the latch springs 938 shown in the
agent injection module 915 of FIGS. 99-101 may be molded with a
number of ratchet teeth (not shown) that engage the proximal end
932 of the collapsible canister 917 as it passes by on the
penetration stroke. If the predetermined depth of penetration is
less than the full stroke, the intermediate teeth retain the
proximal end 932 of the collapsible canister 917 during the
withdrawal stroke in order to collapse the main chamber 918 of the
collapsible canister 917 and dispense the drug or agent 913 as
discussed above.
[0412] In yet another embodiment, drive fingers (not shown) are
secured to an actuation mechanism (not shown) and replace the latch
springs 938. The actuation mechanism is driven electronically in
conjunction with the controllable driver by a processor or
controller, such as the processor 60 discussed above, to control
the rate and amount of drug delivered anywhere in the actuation
cycle. This embodiment allows the delivery of medication during the
actuation cycle as well as the retraction cycle.
[0413] Inherent in the position and velocity control system of a
controllable driver is the ability to precisely define the position
in space of the hypodermic needle 902, allowing finite placement of
the hypodermic needle in the skin 903 for injection of drugs,
vaccines or the like. Drug delivery can be discrete or continuous
depending on the need.
[0414] FIGS. 102-106 illustrate an embodiment of a cartridge 945
that may be used for sampling that has both a lancet cartridge body
946 and an sampling cartridge body 947. The sampling cartridge body
947 includes a plurality of sampling module portions 948 that are
disposed radially from a longitudinal axis 949 of the sampling
cartridge body 947. The lancet cartridge body 946 includes a
plurality of lancet module portions 950 that have a lancet channel
951 with a lancet 183 slidably disposed therein. The lancet module
portions 950 are disposed radially from a longitudinal axis 952 of
the lancet cartridge body 946.
[0415] The sampling cartridge body 947 and lancet cartridge body
946 are disposed adjacent each other in an operative configuration
such that each lancet module portion 950 can be readily aligned in
a functional arrangement with each sampling module portion 948. In
the embodiment shown in FIGS. 102-106, the sampling cartridge body
947 is rotatable with respect to the lancet cartridge body 946 in
order to align any lancet channel 951 and corresponding lancet 183
of the lancet cartridge body 946 with any of the lancet channels
953 of the sampling module portions 948 of the sampling cartridge
body 947. The operative configuration of the relative location and
rotatable coupling of the sampling cartridge body 947 and lancet
cartridge body 946 allow ready alignment of lancet channels 951 and
953 in order to achieve a functional arrangement of a particular
lancet module portion 950 and sampling module portion 948. For the
embodiment shown, the relative motion used to align the particular
lancet module portions 950 and sampling module portions 948 is
confined to a single degree of freedom via relative rotation.
[0416] The ability of the cartridge 945 to align the various
sampling module 948 portions and lancet module portions 950 allows
the user to use a single lancet 183 of a particular lancet module
portion 950 with multiple sampling module portions 948 of the
sampling cartridge body 947. In addition, multiple different
lancets 183 of lancet module portions 950 could be used to obtain a
sample in a single sampling module portion 948 of the sampling
cartridge body 947 if a fresh unused lancet 183 is required or
desired for each lancing action and previous lancing cycles have
been unsuccessful in obtaining a usable sample.
[0417] FIG. 102 shows an exploded view in perspective of the
cartridge 945, which has a proximal end portion 954 and a distal
end portion 955. The lancet cartridge body 946 is disposed at the
proximal end portion 954 of the cartridge 945 and has a plurality
of lancet module portions 950, such as the lancet module portion
950 shown in FIG. 103. Each lancet module portion 950 has a lancet
channel 951 with a lancet 183 slidably disposed within the lancet
channel 951. The lancet channels 951 are substantially parallel to
the longitudinal axis 952 of the lancet cartridge body 946. The
lancets 183 shown have a drive head 198, shaft portion 201 and
sharpened tip 196. The drive head 198 of the lancets are configured
to couple to a drive coupler (not shown), such as the drive coupler
185 discussed above.
[0418] The lancets 183 are free to slide in the respective lancet
channels 951 and are nominally disposed with the sharpened tip 196
withdrawn into the lancet channel 951 to protect the tip 196 and
allow relative rotational motion between the lancet cartridge body
946 and the sampling cartridge body 947 as shown by arrow 956 and
arrow 957 in FIG. 102. The radial center of each lancet channel 951
is disposed a fixed, known radial distance from the longitudinal
axis 952 of the lancet cartridge body 946 and a longitudinal axis
958 of the cartridge 945. By disposing each lancet channel 951 a
fixed known radial distance from the longitudinal axes 952 and 958
of the lancet cartridge body 946 and cartridge 945, the lancet
channels 951 can then be readily and repeatably aligned in a
functional arrangement with lancet channels 953 of the sampling
cartridge body 947. The lancet cartridge body 946 rotates about a
removable pivot shaft 959 which has a longitudinal axis 960 that is
coaxial with the longitudinal axes 952 and 950 of the lancet
cartridge body 946 and cartridge 945.
[0419] The sampling cartridge body 947 is disposed at the distal
end portion 955 of the cartridge and has a plurality of sampling
module portions 948 disposed radially about the longitudinal axis
949 of the sampling cartridge body 947. The longitudinal axis 949
of the sampling cartridge body 947 is coaxial with the longitudinal
axes 952, 958 and 960 of the lancet cartridge body 946, cartridge
945 and pivot shaft 959. The sampling cartridge body 947 may also
rotate about the pivot shaft 959. In order to achieve precise
relative motion between the lancet cartridge body 946 and the
sampling cartridge body 947, one or both of the cartridge bodies
946 and 947 must be rotatable about the pivot shaft 959, however,
it is not necessary for both to be rotatable about the pivot shaft
959, that is, one of the cartridge bodies 946 and 947 may be
secured, permanently or removably, to the pivot shaft 959.
[0420] The sampling cartridge body 947 includes a base 961 and a
cover sheet 962 that covers a proximal surface 963 of the base
forming a fluid tight seal. Each sampling module portion 948 of the
sampling cartridge body 947, such as the sampling module portion
948 shown in FIG. 104 (without the cover sheet for clarity of
illustration), has a sample reservoir 964 and a lancet channel 953.
The sample reservoir 964 has a vent 965 at an outward radial end
that allows the sample reservoir 964 to readily fill with a fluid
sample. The sample reservoir 964 is in fluid communication with the
respective lancet channel 953 which extends substantially parallel
to the longitudinal axis 949 of the sampling cartridge body 947.
The lancet channel 953 is disposed at the inward radial end of the
sample reservoir 964.
[0421] The lancet channels 953 of the sample cartridge body 947
allow passage of the lancet 183 and also function as a sample flow
channel 966 extending from an inlet port 967 of the lancet channel
953, shown in FIG. 106, to the sample reservoir 964. Note that a
proximal surface 968 of the cover sheet 962 is spatially separated
from a distal surface 969 of the lancet cartridge body 946 at the
lancet channel site in order to prevent any fluid sample from being
drawn by capillary action into the lancet channels 951 of the
lancet cartridge body 946. The spatial separation of the proximal
surface 968 of the cover sheet 962 from the distal surface 969 of
the lancet cartridge body 946 is achieved with a boss 970 between
the two surfaces 968 and 969 that is formed into the distal surface
969 of the lancet cartridge body as shown in FIG. 105.
[0422] The sample reservoirs 964 of the sampling cartridge body 947
may include any of the sample detection sensors, testing sensors,
sensor contacts or the like discussed above with regard to other
sampling module embodiments. The cover sheet 962 may be formed of
PMMA and have conductors, sensors or sensor contacts formed on a
surface thereof. It may also be desirable to have the cover sheet
962 made from a transparent or translucent material in order to use
optical sensing or testing methods for samples obtained in the
sample reservoirs. In the embodiment shown, the outer radial
location of at least a portion of the sample reservoirs 964 of the
sampling cartridge body 967 is beyond an outer radial dimension of
the lancet cartridge body 946. Thus, an optical detector or sensor
971, such as shown in FIG. 105, can detect or test a sample
disposed within a sample reservoir 964 by transmitting an optical
signal through the cover sheet 962 and receiving an optical signal
from the sample.
[0423] The cartridge bodies 946 and 947 may have features,
dimensions or materials that are the same as, or similar to,
features, dimensions or materials of the sampling cartridges and
lancet cartridges, or any components thereof, discussed above. The
module portions 948 and 950 may also have features, dimensions or
materials that are the same as, or similar to, features, dimensions
or materials of the lancet or sampling modules, or any components
thereof, discussed above. In addition, the cartridge 945 can be
coupled to, or positioned adjacent any of the drivers discussed
above, or any other suitable driver, in an operative configuration
whereby the lancets of the lancet cartridge body can be selectively
driven in a lancing cycle. Although the embodiment shown in FIGS.
102-106 allows for alignment of various sampling module portions
948 and lancet module portions 950 with relative rotational
movement, other embodiments that function similarly are also
contemplated. For example, lancet module portions, sampling module
portions or both, could be arranged in a two dimensional array with
relative x-y motion being used to align the module portions in a
functional arrangement. Such relative x-y motion could be
accomplished with position sensors and servo motors in such an
alternative embodiment order to achieve the alignment.
[0424] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
appended claims.
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