U.S. patent application number 09/887574 was filed with the patent office on 2002-01-03 for methods and apparatus for sampling and analyzing body fluid.
Invention is credited to Douglas, Joel S., Duchon, Brent G., Radwanski, Ryszard, Roe, Jeffrey N..
Application Number | 20020002344 09/887574 |
Document ID | / |
Family ID | 37000072 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020002344 |
Kind Code |
A1 |
Douglas, Joel S. ; et
al. |
January 3, 2002 |
Methods and apparatus for sampling and analyzing body fluid
Abstract
A sampling device for sampling body fluid includes a lancet for
making an incision, a capillary tube for drawing-up body fluid from
the incision, and a test strip affixed to an upper end of the
capillary tube for receiving the fluid. An absorbent pad can be
disposed between the test strip and capillary tube for
spreading-out the fluid being transferred to the test strip. An
on-site analyzer such as an optical analyzer and/or an
electrochemical analyzer can be mounted in the device for analyzing
the fluid. Alternatively, a test strip can be slid through a slot
formed in the bottom end of the device so that by passing the
device against the skin after an incision has been formed, the test
strip will directly contact body fluid emanating from the
incision.
Inventors: |
Douglas, Joel S.; (Santa
Clara, CA) ; Roe, Jeffrey N.; (San Ramon, CA)
; Radwanski, Ryszard; (Morgan Hill, CA) ; Duchon,
Brent G.; (San Jose, CA) |
Correspondence
Address: |
T. Gene Dillahunty
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
37000072 |
Appl. No.: |
09/887574 |
Filed: |
June 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09887574 |
Jun 21, 2001 |
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09552243 |
Apr 19, 2000 |
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09552243 |
Apr 19, 2000 |
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09298386 |
Apr 23, 1999 |
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6099484 |
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09298386 |
Apr 23, 1999 |
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08858042 |
May 16, 1997 |
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5951492 |
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60017133 |
May 17, 1996 |
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60019918 |
Jun 14, 1996 |
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60023658 |
Aug 1, 1996 |
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60025340 |
Sep 3, 1996 |
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Current U.S.
Class: |
600/583 ;
600/584; 606/181 |
Current CPC
Class: |
A61B 5/150755 20130101;
A61B 5/150213 20130101; A61B 2010/0003 20130101; A61B 5/151
20130101; A61B 5/15117 20130101; A61B 5/150068 20130101; A61B
5/150824 20130101; A61B 5/150358 20130101; A61B 5/150412 20130101;
A61B 2562/0295 20130101; A61B 5/15107 20130101; A61B 5/150022
20130101; A61B 10/0045 20130101; A61B 5/1519 20130101; A61B 5/14532
20130101; A61B 2017/00765 20130101; A61B 2010/008 20130101; A61B
5/157 20130101; A61B 5/15194 20130101 |
Class at
Publication: |
600/583 ;
600/584; 606/181 |
International
Class: |
A61B 005/00 |
Claims
What is claimed is:
1. A sampling device for sampling body fluid, comprising: a
housing; a lancet carrier mounted in the housing and adapted for
supporting a disposable lancet; a mechanism disposed in the housing
for displacing the lancet carrier toward a lower end of the housing
for forming an incision through the skin of a user; and a body
fluid sampling member mounted in the housing for conducting body
fluid from the incision, comprising a capillary member including an
elongated stem having a capillary passage extending longitudinally
therethrough for conducting body fluid upwardly by capillary
action, and a test strip affixed to the capillary member at an
upper end thereof and in communication with the capillary passage
for receiving a sample of body fluid therefrom.
2. The sampling device according to claim 1 wherein the sampling
member further comprises an absorbent pad disposed between the test
strip and the upper end of the capillary passage for wicking body
fluid from the passage to the test strip.
3. The sampling device according to claim 2 wherein the pad is
affixed directly to the capillary member, and the test strip is
affixed directly to the pad.
4. The sampling device according to claim 2, further including an
electrochemical analyzing mechanism mounted in the housing, the
pusher carrying electrical leads arranged for making electrical
connection with a body fluid sample on the test strip, the leads
being electrically connected to the analyzing mechanism.
5. The sampling device according to claim 1, further including an
electrochemical analyzing meter mounted in the housing, a manually
movable element mounted in the housing and carrying electrical
leads arranged to make electrical connection with the meter.
6. The sampling device according to claim 1 further including a
drop detecting mechanism disposed adjacent a lower end of the
device for detecting a drop of body fluid disposed on the user's
skin.
7. The sampling device according to claim 6 wherein the drop
detecting mechanism includes a pair of spaced apart electrodes
arranged to contact the drop and provide a signal to an
indicator.
8. The sampling device according to claim 6 wherein the drop
detecting mechanism comprises a light emitter and light receiver
disposed adjacent a lower end of the device and provide a signal to
an indicator.
9. A sampling device for sampling body fluid, comprising: a
housing; a lancet carrier mounted in the housing and adapted for
supporting a disposable lancet; a mechanism for displacing the
lancet carrier toward a lower end of the housing for forming an
incision through the skin of a user; and a strip-holding mechanism
mounted at a lower end of the housing for supporting a test strip
across the lower end of the housing to enable the test strip to
pick-up body fluid from the incision.
10. The sampling device according to claim 9 wherein the
strip-holding mechanism comprises a sleeve surrounding the lancet
carrier and including slots for receiving the test strip.
11. The sampling device according to claim 10 wherein the sleeve
constitutes a first sleeve, the strip-holding mechanism further
including a second sleeve surrounding the first sleeve and
including slots radially aligned with the slots of the first
sleeve, the second sleeve being slidable longitudinally relative to
both the housing and the first sleeve and being spring biased
downwardly, the slots formed in the second sleeve being elongated
in a direction parallel to a longitudinal axis of the housing to
enable the second sleeve to move longitudinally relative to a test
strip mounted in the first sleeve.
12. A sampling device for sampling body fluid, comprising: a
housing; means in the housing for forming an incision through the
skin of a user; and a drop-detecting mechanism disposed adjacent a
lower end of the device for detecting a drop of body fluid disposed
on the user's skin.
13. The sampling device according to claim 12 wherein the drop
detecting mechanism includes a pair of spaced apart electrodes
arranged to contact the drop.
14. The sampling device according to claim 12 wherein the drop
detecting mechanism comprises a light emitter and light receiver
disposed adjacent a lower end of the device.
15. A method of sampling body fluid comprising the steps of: A)
positioning a lower end of a sampling device against a skin
surface; B) displacing a lancet toward the lower end of the
sampling device to form an incision through the skin; C) mounting a
test strip in the sampling device to extend across the lower end
thereof; and D) moving the sampling device toward the incision to
bring the test strip into contact with body fluid emerging from the
incision.
16. The method according to claim 15 wherein step C is performed
prior to step B whereby the lancet pierces the test strip when
displaced to form the incision.
17. A body fluid sampling member adapted to be mounted in a device
for sampling body fluid, comprising: a capillary member including
an elongated stem having a capillary passage extending
longitudinally therethrough for conducting body fluid upwardly by
capillary action; and a test strip affixed to the capillary member
at an upper end thereof and in communication with the capillary
passage for receiving a sample of body fluid.
18. The body fluid sampling member according to claim 17 further
including a covering structure covering portions of the absorbent
pad not covered by the membrane; the covering structure being
vented by at least one air vent opening having a smaller cross
section than the passage.
19. The body fluid sampling member according to claim 18 wherein
the covering structure includes a flange projecting laterally
outwardly from an upper end of the stem, a lower surface of the pad
being seated on the flange.
20. The body fluid sampling member according to claim 19 wherein
the covering structure further includes a side cover extending
around a side surface of the pad.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to lancing devices and methods
for obtaining samples of blood and other fluids from the body for
analysis or processing.
BACKGROUND OF THE INVENTION
[0002] Many medical procedures in use today require a relatively
small sample of blood, in the range of 5-50 .mu.L. It is more cost
effective and less traumatic to the patient to obtain such a sample
by lancing or piercing the skin at a selected location, such as the
finger, to enable the collection of 1 or 2 drops of blood, than by
using a phlebotomist to draw a tube of venous blood. With the
advent of home use tests such as self monitoring of blood glucose,
there is a requirement for a simple procedure which can be
performed in any setting by a person needing to test.
[0003] Lancets in conventional use generally have a rigid body and
a sterile needle which protrudes from one end. The lancet may be
used to pierce the skin, thereby enabling the collection of a blood
sample from the opening created. The blood is transferred to a test
device or collection device. Blood is most commonly taken from the
fingertips, where the supply is generally excellent. However, the
nerve density in this region causes significant pain in many
patients. Sampling of alternate site, such as earlobes and limbs,
is sometimes practiced to access sites which are less sensitive.
These sites are also less likely to provide excellent blood samples
and make blood transfer directly to test devices difficult.
[0004] Repeated lancing in limited surface areas (such as
fingertips) results in callous formation. This leads to increased
difficulty in drawing blood and increased pain.
[0005] To reduce the anxiety of piercing the skin and the
associated pain, many spring loaded devices have been developed.
The following two patents are representative of the devices which
were developed in the 1980's for use with home diagnostic test
products.
[0006] U.S. Pat. No. 4,503,856, Cornell et al., describes a spring
loaded lancet injector. The reusable device interfaces with a
disposable lancet. The lancet holder may be latched in a retracted
position. When the user contacts a release, a spring causes the
lancet to pierce the skin at high speed and then retract. The speed
is important to reduce the pain associated with the puncture.
[0007] Levin et al. U.S. Pat. No. 4,517,978 describes a blood
sampling instrument. This device, which is also spring loaded, uses
a standard disposable lancet. The design enables easy and accurate
positioning against a fingertip so the impact site can be readily
determined. After the lancet pierces the skin, a bounce back spring
retracts the lancet to a safe position within the device.
[0008] In institutional settings, it is often desirable to collect
the sample from the patient and then introduce the sample to a test
device in a controlled fashion. Some blood glucose monitoring
systems, for example, require that the blood sample be applied to a
test device which is in contact with a test instrument. In such
situations, bringing the finger of a patient directly to the test
device poses some risk of contamination from blood of a previous
patient. With such systems, particularly in hospital settings, it
is common to lance a patient, collect a sample in a micropipette
via capillary action and then deliver the sample from the pipette
to the test device.
[0009] Haynes U.S. Pat. No. 4,920,977 describes a blood collection
assembly with lancet and microcollection tube. This device
incorporates a lancet and collection container in a single device.
The lancing and collection are two separate activities, but the
device is a convenient single disposable unit for situations when
sample collection prior to use is desirable. Similar devices are
disclosed in Sarrine U.S. Pat. No. 4,360,016, and O'Brien U.S. Pat.
No. 4,924,879.
[0010] Jordan et al. U.S. Pat. No. 4,850,973 and No. 4,858,607,
disclose a combination device which may be alternatively used as a
syringe-type injection device and a lancing device with disposable
solid needle lancet, depending on configuration.
[0011] Lange et al. U.S. Pat. No. 5,318,584 describes a blood
lancet device for withdrawing blood for diagnostic purposes. This
invention uses a rotary/sliding transmission system to reduce the
pain of lancing. The puncture depth is easily and precisely
adjustable by the user.
[0012] Suzuki et al. U.S. Pat. No. 5,368,047, Dombrowski U.S. Pat.
No. 4,654,513 and Ishibashi et al. U.S. Pat. No. 5,320,607 each
describe suction-type blood samplers. These devices develop suction
between the lancing site and the end of the device when the lancet
holding mechanism withdraws after piercing the skin. A flexible
gasket around the end of the device helps seal the end around the
puncture site until adequate sample is drawn from the puncture site
or the user pulls back on the device.
[0013] Garcia et al. U.S. Pat. No. 4,637,403 discloses a
combination lancing and blood collection device which uses a
capillary passage to conduct body fluid to a separate test strip in
the form of a microporous membrane. It is necessary to achieve a
precise positioning of the upper end of the capillary passage with
respect to the membrane in order to ensure that body fluid from the
passage is transferred to the membrane. If an appreciable gap
exists therebetween, no transfer may occur.
[0014] Also, the diameter of the capillary passage is relatively
small, so the width of a sample transferred to the membrane may be
too small to be measured by on-site measuring devices such as an
optical measuring system or an electrochemical meter.
[0015] It is difficult for a user to determine whether a
sufficiently large drop of body fluid has been developed at the
incision for providing a large enough sample.
[0016] International Publication Number WO95/10223, Erickson et
al., describes a means of collecting and measuring body fluids.
This system uses a disposable lancing and suction device with a
spacer member which compresses the skin around the
lance/needle.
[0017] Single use devices have also been developed for single use
tests, i.e. home cholesterol testing, and for institutional use to
eliminate cross-patient contamination multi-patient use. Crossman
et al. U.S. Pat. No. 4,869,249, and Swierczek U.S. Pat. No.
5,402,798, also disclose disposable, single use lancing
devices.
[0018] The disclosures of the above patents are incorporated herein
by reference.
[0019] An object of the present invention is to ensure that a
sufficiently large drop of body fluid is developed at an incision,
and that the body fluid reaches a test strip.
[0020] Another object is to ensure that the sample applied to the
test strip creates a measurement area that is sufficiently wide to
be properly analyzed.
[0021] An additional object is to provide a novel electrochemical
analyzing system for analyzing a sample in the lancing device.
[0022] A further object is to enable a sample of body fluid to be
applied to a test strip which is mounted in a lancing device.
[0023] Another object of this invention is to provide a method
which can result in a sample of either blood or interstitial fluid,
depending on the sample site and the penetration depth utilized.
While there are no commercially available devices utilizing
interstitial fluid (ISF) at this time, there are active efforts to
establish the correlation of analytes, such as glucose, in ISF
compared to whole blood. If ISF could be readily obtained and
correlation is established, ISF may be preferable as a sample since
there is no interference of red blood cells or hematocrit
adjustment required.
[0024] Another object of this invention is to provide a method
which can draw a small but adjustable sample, i.e. 3 .mu.L for one
test device and 8 .mu.L for another test device, as
appropriate.
[0025] Another object of this invention is to provide a method by
which the drawn sample is collected and may be easily presented to
a testing device, regardless of the location of the sample site on
the body. This approach helps with infection control in that
multiple patients are not brought in contact with a single test
instrument; only the sampling device with a disposable
patient-contact portion is brought to the test instrument.
Alternatively, the disposable portion of a test device may be
physically coupled with the sampler so the sample can be brought
directly into the test device during sampling. The test device may
then be read in a test instrument if appropriate or the testing
system can be integrated into the sampler and the test device can
provide direct results displayed for the patient.
[0026] A further object is to provide an on-site test strip with a
relatively wide sample which can be analyzed by on-site analyzers
such as optical and electrochemical analyzers.
[0027] It is a further object of the invention is to provide a
device for minimally invasive sampling comprising a reusable
sampler and disposable lancet and sample collection device.
SUMMARY OF THE INVENTION
[0028] One aspect of the present invention relates to a sampling
device for sampling body fluid. The device includes a housing and a
lancet carrier mounted in the housing for supporting a disposable
lancet. The device also includes a mechanism for displacing the
lancet carrier toward a lower end of the housing for forming an
incision in a user. A body fluid sampling member is mounted in the
housing for conducting body fluid from the incision. That sampling
member comprises a capillary member, and a test strip. The
capillary member includes an elongated stem having a capillary
passage extending longitudinally therethrough for conducting body
fluid upwardly by capillary action. The test strip is affixed to
the capillary member at an upper end thereof and in communication
with the capillary passage for receiving a sample of body
fluid.
[0029] Preferably, the test strip comprises a microporous membrane,
and an absorbent pad is preferably disposed between the test strip
and the upper end of the capillary passage for wicking body fluid
from the passage to the test strip.
[0030] The present invention also relates to the capillary member
per se.
[0031] Another embodiment of the sampling device includes a
housing, a lancet carrier mounted in the housing for supporting a
disposable lancet, a mechanism for displacing the lancet carrier
toward a lower end of the housing for forming an incision in a
user, and a strip-holding mechanism mounted at a lower end of the
housing for supporting a test strip across the lower end of the
housing to enable the test strip to pick up body fluid from the
incision.
[0032] The strip holding mechanism preferably comprises a sleeve
disposed in surrounding relationship to the lancet carrier and
includes radially aligned slots for receiving a test strip.
[0033] Preferably, the sleeve constitutes a first sleeve, and the
holding mechanism further includes a second sleeve surrounding the
first sleeve and including slots that are radially aligned with the
slots of the first sleeve. The second sleeve is slidable
longitudinally relative to both the housing and the first sleeve
and is spring biased downwardly. The slots which are formed in the
second sleeve are elongated in a direction parallel to a
longitudinal axis of the housing to enable the second sleeve to
move longitudinally relative to a test strip mounted in the first
sleeve.
[0034] The present invention also relates to a method of sampling
body fluid which comprises the steps of positioning a lower end of
a sampling device against a skin surface, and displacing a lancet
carrier toward the lower end of the sampling device to form an
incision through the skin. A test strip is positioned in the
sampling device to extend across the lower end thereof. The
sampling device is moved toward the incision to bring the test
strip into contact with body fluid emerging from the incision. The
test strip is preferably positioned in the sampling device prior to
the displacement of the lancet toward the lower end of the sampling
device, whereby the lancet pierces the test strip.
[0035] Another aspect of the invention involves the provision of a
drop-detecting mechanism on the lancing device adjacent a lower end
thereof for detecting a drop of body fluid on the user's skin. The
mechanism can be in the form of electrodes which contact the drop,
or an optical system including a light emitter and a light sensor.
The drop-detecting mechanism automatically determines whether a
drop of sufficient size has been developed at the incision for
providing a proper sample.
BRIEF DESCRIPTION OF THE DRAWING
[0036] The objects and advantages of the invention will become
apparent from the following detailed description of preferred
embodiments thereof in connection with the accompanying drawing in
which like numerals designate like elements and in which:
[0037] FIG. 1 is a side elevational view, partially broken away, of
a blood sampling device according to the present invention, with a
capillary tube thereof disposed in a retracted state;
[0038] FIG. 2 is a view similar to FIG. 1 after an incision has
been made, and the capillary tube has been extended;
[0039] FIG. 3 is a longitudinal sectional view through one
embodiment of the capillary tube according to the present
invention;
[0040] FIG. 4 is a longitudinal sectional view taken through
another embodiment of a capillary tube according to the present
invention;
[0041] FIG. 5 is view similar to FIG. 2 of a sampling device having
an alternative form of analyzing instrument;
[0042] FIG. 6 is a fragmentary view of a lower end of a lancing
device, depicting a drop-detecting mechanism according to the
present invention;
[0043] FIG. 7 is a side elevational view, partially broken away of
another embodiment of the sampling device, with a test strip
mounted at a lower end thereof; and
[0044] FIG. 8 is a fragmentary view of the device depicted in FIG.
6 in a sampling-taking state.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0045] Depicted in FIGS. 1 and 2 is a lancing device 10 for making
an incision through a skin surface S, wherein a disposable lancet
12 (hereinafter referred to as a "disposable") which carries a
skin-lancing member in the form of a needle 14 can be displaced
toward the skin surface by a cocked spring and then rapidly
retracted by another spring. Devices of this general type are
known, and one preferred device is disclosed in commonly assigned,
concurrently filed U.S. Pat. No. 5,879,311, the disclosure of which
is incorporated herein by reference.
[0046] As disclosed in that application, the disposable 12 includes
a body 16 which carries not only the needle 14, but also a
capillary tube 18. The capillary tube is mounted by friction fit
between holding elements 15 that are integral with the body 16 and
is downwardly slidable relative to the body 16 in response to
manual downward displacement of a pusher 20 which possesses an
exposed actuator knob 22.
[0047] The disposable 12 is situated telescopingly within a
cylindrical stimulator sleeve 24 which is slidable longitudinally
relative to a housing 26 of the device. The sleeve 24 is biased
downwardly, or forwardly, by a spring 28. Following the cutting of
an incision I in the skin and the retraction of the lancet, the
housing can be repeatedly pushed downwardly against the skin as
required to express the appropriate sample from the incision,
whereupon the sleeve depresses a ring of body tissue in surrounding
relationship to the incision, causing the incision to bulge while
spreading apart the sides of the incision. Consequently, a drop D
of body fluid such as blood or interstitial fluid is formed at the
open end of the incision, even if the incision I has been made in a
region of the body where the supply of body fluid is relatively low
as compared to, say, the fingertip region.
[0048] Once the drop D has been created, the pusher 22 is displaced
to push the capillary tube downwardly to a state where the lower
end of the capillary tube can be dipped into the body fluid drop to
obtain a sample. The pusher is then released for return to an upper
position by a return spring (not shown). As disclosed in the
aforementioned application, the fluid can then be transferred from
the capillary tube to a test strip, thereby making the overall
sampling procedure more convenient.
[0049] In accordance with the present invention, the sampling
procedure is made even more convenient by eliminating the need to
transfer the body fluid from the capillary tube.
[0050] In a first embodiment, the capillary tube carries its own
test strip. Depicted in FIG. 3 is a test strip 30 in the form of a
microporous membrane (preferably of the type disclosed in commonly
assigned U.S. application Ser. No. 08/628,489, filed Apr. 5, 1996,
the disclosure of which is incorporated by reference herein).
[0051] The membrane 30 is bonded, e.g. by a suitable adhesive, to
an enlarged head or flange portion 32 of the capillary tube 18
which projects laterally with respect to a stem portion 34 of the
capillary tube. The head 32, when viewed from the top, can be of
any shape, such as circular or rectangular (e.g., square). A
capillary passage 36 extends longitudinally through the stem 34 and
head 32 to conduct body fluid into contact with the membrane by
capillary action.
[0052] As is known in the art of capillary tubes, the amount of
body fluid which is drawn up by capillary action can be regulated
by a suitable selection of diameter and length of the passage 36,
thereby ensuring that a proper dosing of the membrane is
achieved.
[0053] Fluid analyzing instruments can be mounted within the
housing. For example, a conventional optical analyzing mechanism
can be provided which includes a light source 40 and a light sensor
42 such as a phototransistor, which are electrically connected to a
conventional electronics unit 44 for monitoring a color change of
the sample as the sample reacts with chemicals in the test strip.
The electronics unit 44 displays the results on a display panel 90.
In that way, for example, the glucose level in blood can be
measured. The unit 44 is electrically connected to a battery 45
that is mounted in the housing.
[0054] In lieu of an optical analyzing mechanism, an
electrochemical mechanism can be provided in a device 10' (FIG. 5),
the mechanism including an electrochemical meter 50 which measures
glucose levels. The meter 50 is electrically connected to a battery
51 mounted in the housing. The test strip 52 in this case would be
provided with a printed electrical circuit, and the pusher 24'
would possess electrical leads 54 positioned so as to contact
respective portions of the printed circuit electrical paths on the
test strip when the pusher 24' is in its lower position (after
having pushed the capillary tube down). Thus, the sample conducted
to the test strip 52 by the capillary tube will contact the
electrical circuit for conducting a current therebetween when the
leads 54 are brought into contact with the circuit. The leads are
connected to the meter 50 which measures the current. Since the
level of current is proportional to the glucose concentration, the
meter 50 is able to measure that concentration.
[0055] When the disposable 12 is discarded after a testing
operation, the capillary tube 18 and test strip 30 will be
discarded therewith. A fresh disposable is then installed to
present a new lancet 14, capillary tube 18 and test strip 30. Thus,
the user never has to touch or otherwise maneuver a test strip
separately from the capillary tube, since the test strip is
attached thereto.
[0056] An alternate embodiment of a capillary tube 18' is depicted
in FIG. 4 wherein an absorbent pad 60 is disposed between the test
strip 30 and the head 32' of the capillary tube 18'. That is, the
absorbent pad, which can be formed of cellulose or suitable
membrane, is bonded to the capillary tube 18', and the membrane 30
is bonded to the absorbent pad, or to a ring 62 which extends
around a circumferential outer edge face of the absorbent pad 60.
That ring, together with the flange 32, forms a cover which covers
portions of the absorbent pad not covered by the membrane 30 to
prevent the escape of the body fluid sample. When the capillary
tube draws-up body fluid by capillary action, that fluid is wicked
by the absorbent pad and supplied to the test strip 30. An
advantage of the capillary tube 18' is that the absorbent pad will
spread-out the fluid so that a wider sample is applied to the test
strip to facilitate analysis.
[0057] A backpressure may occur which opposes a flow of body fluid
through the absorbent pad 60. To deal with that potential problem,
the head 32' is provided with air vent openings 64 to relieve the
backpressure and facilitate the flow of fluid through the pad 60.
The air vents are spaced laterally from the passage 36 and
communicate with the pad. The diameter of the vent openings is
smaller than that of the capillary tube and small enough to prevent
the passage of body fluid therethrough.
[0058] Instead of being bonded directly to the absorbent pad 60,
the membrane 30 could be bonded to the cover 62. In that case, the
absorbent pad 60 could be bonded to the membrane, or to the cover,
or to the capillary tube.
[0059] In any event it will be appreciated that the test strip is
affixed, either directly or indirectly, to the capillary tube to
constitute an integral part thereof.
[0060] One problem faced by a user is being able to determine
whether a drop of body fluid expressed from an incision is of
sufficient size to provide a proper sample. That determination can
be made automatically by a sampling device 10" in accordance with
an embodiment of the invention depicted in FIG. 6 wherein a drop
sensing mechanism 65 is mounted on an inner sleeve 66. The drop
sensing mechanism comprises a pair of diametrically opposed
elements 67, 68. In one embodiment, those elements comprise a pair
of electrodes connected by wires 69 to the battery 45 or 51 and
positioned such that when the outer sleeve 24 is retracted in
response to a pressing down of the housing, the electrodes will
make contact with the drop of body fluid only if the drop is of
sufficient. height to provide an adequate sample. If such contact
is made, the drop will close a circuit, enabling a sensor to
determine that the drop is of ample size. An indicator, such as a
lamp 71 can be energized to advise the user.
[0061] Alternatively, the elements 67, 68 of the mechanism 65 could
comprise a light emitter and light receiver, respectively. When the
drop of body fluid is of sufficient height, it will block the
transmission of light to the receiver, thus indicating that the
drop is of sufficient size, and triggering the energization of the
lamp 71.
[0062] The drop-detecting mechanism 65 can be used with either of
the embodiments disclosed in connection with FIGS. 1-2 and 5.
However, it is not necessary that the incision be formed by a
lancet. Other incision forming devices could be used such as a
laser beam or pressurized fluid. That is, known pneumatic or
hydraulic injectors of the type which inject pressurized gas or
liquid against the skin could be used. Such auto injectors are sold
by Becton-Dickinson, for example, to inject insulin. By eliminating
the insulin and merely injecting the gas (e.g., air or nitrogen) or
liquid (e.g., water) at pressures above 30 psi. an incision could
be formed in the skin for taking samples of body fluid.
Advantageously, small particles could be mixed with the gas to
promote the tissue-cutting action. The particles could comprise
carbon particles of from 1 micron to 0.010 inches in diameter.
[0063] Another embodiment of a sampling device 10" according to the
invention is depicted in FIGS. 7 and 8. In that embodiment, the
stimulator sleeve 24" is provided with a through-slot 70, and an
inner sleeve 72 (which supports the disposable), is provided with a
through-slot 74 that is aligned with the through-slot 70. Those
aligned through-slots 70, 74 are adapted to receive a test strip
30" which, if desired, includes an absorbent pad 60". The test
strip 30", which may comprise a porous membrane 30A" and an
absorbent pad 30B" attached thereto, is manually inserted through
the slots 70, 74 by the user.
[0064] When a lancing procedure is performed, the lancet pierces
the test strip 30" en route to the skin surface. Then, as the
housing is repeatedly pushed down to pump body fluid to the open
end of the incision as described earlier, the stimulator sleeve 24"
will be repeatedly retracted, and simultaneously the inner sleeve
72, along with the test strip 30", will approach and contact the
drop of body fluid as shown in FIG. 8, whereby a sample of the
fluid is collected on the test strip.
[0065] Then, the user removes the test strip for testing at an
off-site analyzer.
[0066] It will be appreciated that the present invention enables a
test strip to be easily installed into and removed from a lancing
device, thereby minimizing any risk of contamination of the sample.
In the examples according to FIGS. 1-5 the test strip is installed
along with the disposable lancet, thereby being automatically
positioned in proper relationship to receive a sample and to permit
the sample to be analyzed by an on-side analyzing instrument. If
desired, however, the analysis could be performed by an off-site
instrument by removing the disposable from the device and taking it
to the off-site instrument. In the example of FIGS. 7-8, the test
strip is easily installed/removed by being passed through readily
accessible slots.
[0067] Although the present invention has been described in
connection with preferred embodiments thereof, it will be
appreciated by those skilled in the art that additions,
modifications, substitutions and deletions not specifically
described may be made without departing from the spirit and scope
of the invention as defined in the appended claims.
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