U.S. patent application number 10/864933 was filed with the patent office on 2004-11-11 for lancing device and method of sample collection.
This patent application is currently assigned to TheraSense, Inc.. Invention is credited to Flynn, Stephen J., Kennedy, Gwenn E., Levaughn, Richard W., Lipoma, Michael V..
Application Number | 20040225311 10/864933 |
Document ID | / |
Family ID | 23667302 |
Filed Date | 2004-11-11 |
United States Patent
Application |
20040225311 |
Kind Code |
A1 |
Levaughn, Richard W. ; et
al. |
November 11, 2004 |
Lancing device and method of sample collection
Abstract
A lancing device and method for self-collecting a sample of body
fluid by penetrating a body tissue at a sampling site. The
invention includes a housing geometry configured for ease of use at
different sampling sites on the body, even by persons having
reduced dexterity and/or poor vision. Depth of penetration is
selectively controlled by adjusting the stroke range of a
spring-driven lancet carrier. A pressure applicator is included for
stimulating flow of the body fluid. A transparent portion permits
observation of the sampling site.
Inventors: |
Levaughn, Richard W.;
(McDonough, GA) ; Flynn, Stephen J.; (Peachtree
City, GA) ; Kennedy, Gwenn E.; (Ellenwood, GA)
; Lipoma, Michael V.; (Villa Rica, GA) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
TheraSense, Inc.
Alameda
CA
|
Family ID: |
23667302 |
Appl. No.: |
10/864933 |
Filed: |
June 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10864933 |
Jun 9, 2004 |
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09929649 |
Aug 14, 2001 |
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6749618 |
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09929649 |
Aug 14, 2001 |
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09420649 |
Oct 19, 1999 |
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6283982 |
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Current U.S.
Class: |
606/181 |
Current CPC
Class: |
A61B 5/150412 20130101;
A61B 5/150022 20130101; A61B 5/1513 20130101; A61B 5/150824
20130101; A61B 5/15194 20130101; A61B 5/15117 20130101; A61B
5/15113 20130101; A61B 5/150068 20130101; A61B 5/15019 20130101;
A61B 5/150816 20130101; A61B 5/150259 20130101 |
Class at
Publication: |
606/181 |
International
Class: |
A61B 017/34 |
Claims
1-30. (Canceled)
31. A lancing device for use with a lancet to penetrate tissue and
facilitate collection of a sample of a body fluid, the lancing
device comprising: (a) a housing having front and back housing
shells; (b) a lancet carrier mounted with the housing for
releasably carrying a lancet having a tissue penetrating portion
from a retracted to position to an extended position; (c) a
transparent plastic end cap removably and releasably attachable to
the housing, the end cap comprising; (i) an opening for allowing
passage of the tissue penetrating portion of the lancet through the
cap, the opening having a diameter less than a diameter of the
lancet yet greater than a diameter of the tissue penetrating
portion; and (ii) a pressure applicator surrounding the opening;
(d) a cocking actuator operably connected to the lancet carrier;
and (e) a trigger button operably connected to the lancet carrier
and to the cocking actuator, the trigger button positioned on the
lancing device between the cocking actuator and the transparent end
cap.
32. The lancing device according to claim 31 further comprising
stroke control means for controlling the distance the tissue
penetrating portion of the lancet extends beyond the opening in the
end cap when the lancet carrier is moved to the extended position,
the stroke control means comprising indexing means to provide
tactile feedback.
33. The lancing device according to claim 32, wherein the stroke
control means has at least five positions.
34. The lancing device according to claim 31, wherein the pressure
applicator comprises a raised lip around at least a portion of the
opening.
35. The lancing device according to claim 34, wherein the raised
lip is an annular ring.
36. The lancing device according to claim 34, wherein the raised
lip is adjacent the opening.
37. The lancing device according to claim 34, wherein the raised
lip projects 1 mm to 3 mm.
38. The lancing device according to claim 31, wherein the pressure
applicator comprises a forward-facing annular land surrounding the
opening.
39. The lancing device according to claim 38, wherein the
forward-facing annular land is about 2 mm across.
40. The lancing device according to claim 31, wherein the opening
has a diameter of 4 mm to 8 mm.
41. A method of collecting a body fluid sample, the method
comprising: (a) positioning a lancing device on a desired sample
site, the lancing device comprising: (i) a housing having front and
back housing shells; (ii) a lancet carrier mounted with the housing
for releasably carrying a lancet having a tissue penetrating
portion from a retracted to position to an extended position; (iii)
a transparent plastic end cap removably and releasably attachable
to the housing, the end cap comprising; (A) an opening for allowing
passage of the tissue penetrating portion of the lancet through the
cap, the opening having a diameter less than a diameter of the
lancet yet greater than a diameter of the tissue penetrating
portion; and (B) a pressure applicator surrounding the opening;
(iv) a cocking actuator operably connected to the lancet carrier;
and (v) a trigger button operably connected to the lancet carrier
and to the cocking actuator, the trigger button positioned on the
lancing device between the cocking actuator and the transparent end
cap; (b) actuating the cocking actuator; (c) pressing the pressure
applicator against the sample site; (d) pressing the trigger button
to release the lancet so that the tissue penetrating portion
penetrates the sample site; and (e) monitoring the sample site
through the transparent end cap.
42. (Canceled)
43. The method according to claim 41, wherein the step of pressing
the pressure applicator against the sample site comprises: (a)
applying compressive pressure to the sample site.
44. The method according to claim 43, wherein the step of applying
compressive pressure to the sample site comprises: (a) applying
steady compressive pressure to the sample site.
45. The method according to claim 43, wherein the step of applying
compressive pressure to the sample site comprises: (a) applying
varying compressive pressure to the sample site.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to devices and
methods for use in medical sampling and testing, and more
particularly to a lancing device and a method for penetrating body
tissue to obtain a sample of body fluid.
BACKGROUND OF THE INVENTION
[0002] Samples of blood, interstitial fluid, or other body fluids
are commonly required for various medical purposes. For example,
many diabetics must periodically monitor their blood glucose level
to determine when an insulin injection is needed. Self-testing
systems are available to enable a person to obtain a sample of his
or her own blood, typically by penetrating the skin, and to subject
the harvested blood sample to analysis of the blood glucose level.
Often, a lancing device is used to penetrate the skin to obtain the
required sample of blood. For example, U.S. Pat. Nos. 5,954,738;
5,879,311; 5,857,983; and 5,318,584 disclose particular forms of
body fluid sampling devices.
[0003] In order to encourage compliance in regular usage, it is
highly desirable that the use of a lancing device be as painless as
possible to a subject obtaining a blood sample. Because the
fingertips are rich in capillaries, a number of lancing devices
have been designed for sample collection from this region. Nerve
density is high in the fingertips, however, and significant pain
often results from fingertip sampling. Moreover, repeated sampling
can adversely result in callous formation on the fingertips.
Accordingly, testing procedures have been developed allowing
sampling at other sites on the body, such as the earlobe or
forearm. By appropriate selection of the sampling site, the lancet
geometry and the depth of penetration, the required sample size is
obtained. According to present and developing sampling methods,
sample sizes of about 8-10 microliters (.mu.L), and in some
instances about 2-3 microliters (.mu.L), and possibly as little as
about 400 nanoliters (nL) are sufficient for blood glucose
analysis. It is anticipated that continuing developments in the
field will progressively reduce the required sample size. In order
to minimize pain and speed healing, it is desirable to minimize the
size of the opening in the skin that is required to obtain a sample
of the requisite size. To further reduce pain, it is also desirable
that the lancing operation incorporate a quick penetration and
retraction stroke, wherein the piercing instrument penetrates the
skin and is quickly retracted along a substantially linear
path.
[0004] It has also been found advantageous to provide a lancing
device that is configured for ease of manipulation and use at
different sampling sites. This is of particular importance with
lancing devices intended for use by diabetics, as many diabetics
suffer from poor eyesight and neuropathy, often resulting in
reduced manual dexterity. Many previously known lancing devices
have been found particularly difficult for such users to manipulate
in carrying out certain sampling methods. For example, pen-shaped
lancing devices are often too narrow for some users to grasp
easily, and their cylindrical shape may render them difficult for
some users to hold without unintentional twisting of the barrel of
the device. Also, because such devices are typically relatively
long compared to their width (or diameter) it is difficult for some
users to apply sufficient pressure to maintain the device in a
stable manner against the user's forearm during sampling. Other
lancing devices incorporate non-symmetric or non-rectangular
housings and/or housings with gripping surfaces or sample site
contacting surfaces that are offset at oblique angles from the
stroke axis of their lancets. Such devices are generally adapted
for fingertip sampling, but are not well-suited for sampling at a
site on the forearm. In particular, due to their angular offset,
many users find it difficult to press these lancing devices against
the forearm while maintaining the device in an orientation for
lancing perpendicularly to the skin.
[0005] A number of previously known lancing devices enable
penetration of the skin to a single, predetermined depth. Because
of differences between individual users, such devices may generate
a sample size larger or smaller than necessary. Accordingly it is
desirable to provide a lancing device that enables easy adjustment
of the depth of penetration, and that provides a reliable and
accurate depth stop for providing a desired depth of
penetration.
[0006] For purposes of commercial appeal to consumers, it has been
found desirable to provide a lancing device that is compatible with
standard, commercially available, disposable lancets. It is
preferable that a standard lancet be readily mountable to a lancing
device prior to use, and that the lancet also be readily and safely
removable from the lancing device for deposit in a sharps container
or other disposal canister. Particular forms of previously known
lancing devices have incorporated an eject feature that permits a
lancet to be "launched" from the device, potentially resulting in
injury. Other known devices require the user to grasp the used
lancet for removal, thereby presenting a risk of needle sticks.
Accordingly, it would be preferable to provide a lancing device
enabling safer and more controlled release of a lancet.
[0007] Certain previously known sampling devices provide for the
application of pressure to tissue surrounding an incision to
stimulate the formation of a drop of sampled fluid. The
configuration of previously known stimulator members has been found
to provide less than optimal sampling rates, to result in
undesirable levels of user discomfort, and to result in bruising or
marking of the skin with pressure indentations. In addition, it is
often difficult to monitor the sample size produced during use of
such previously known devices. Accordingly, it would be preferable
to provide a lancing device providing improved stimulation of
sample generation and easier monitoring of sample size.
[0008] Thus it can be seen that a need exists for an improved
lancing device and methods for penetrating tissue to facilitate
collection of a sample of a body fluid. It is to the provision of
improved lancing devices and methods meeting these and other needs
that the present invention is primarily directed.
SUMMARY OF THE INVENTION
[0009] The present invention comprises improved lancing devices and
methods for penetrating tissue to facilitate collection of a sample
of a body fluid. In a preferred aspect, the present invention
comprises a lancing device for use with a lancet to penetrate
tissue and facilitate collection of a sample of a body fluid. The
lancing device preferably includes a housing; a lancet carrier
translationally mounted to the housing for carrying a lancet along
a stroke traversing an extended position wherein a tissue
penetrating portion of the lancet extends a distance outwardly of
the housing, the lancet carrier comprising a limit member; and a
thumbwheel rotationally mounted to the housing, and comprising an
eccentric contact surface forming a selectively movable stop for
contacting the limit member to limit the stroke of the lancet
carrier in the direction of the extended position.
[0010] Accordingly, depth of penetration is easily and accurately
adjusted to suit the needs of the individual user, and to produce
the required sample size with minimal pain to the user and promote
quick healing. Additionally, by minimizing the size of the wound
necessary to generate a desired sample size, the wound closes
quickly after sampling to reduce the incidence of residual bleeding
that may stain the user's clothing.
[0011] The lancing device of the present invention preferably
engages a standard lancet, and also provides safe and controlled
release of the lancet for disposal. In a preferred aspect, the
lancing device of the present invention includes a housing, and a
lancet carrier mounted to the housing for releasably engaging a
lancet. The lancet carrier preferably comprises a first gripping
jaw; a second gripping jaw positioned in opposition to the first
gripping jaw to define a lancet-receiving channel between the first
and second gripping jaws, the first and second gripping jaws being
movable between a closed position for gripping a lancet and an open
position for receiving and releasing a lancet; biasing means for
biasing the first and second gripping jaws toward the closed
position; and a first release arm connected to the first gripping
jaw and a second release arm connected to the second gripping jaw,
whereby application of force to the first and second release arms
moves the first and second gripping jaws toward the open
position.
[0012] In another preferred aspect, the present invention comprises
a lancing device for use with a lancet to penetrate tissue and
facilitate collection of a sample of a body fluid. The lancing
device preferably includes a housing having a forward end and a
transparent portion adjacent the forward end. The lancing device
preferably further includes a lancet carrier mounted to the housing
for carrying a lancet between a retracted position within the
housing and an extended position wherein a tissue penetrating
portion of the lancet extends a distance beyond the forward end of
the housing. The lancing device preferably further includes a
pressure applicator adjacent the forward end of the housing.
[0013] In another preferred aspect, the present invention comprises
a lancing device for use with a lancet to penetrate tissue and
facilitate collection of a sample of a body fluid. The lancing
device preferably includes a housing having an overall length, an
overall width, and an overall thickness, the overall length being
no more than about four times the overall width, and the overall
width being at least about one and one-half times the overall
thickness, wherein the housing is generally symmetric about
perpendicular first and second planes of symmetry, and wherein a
trigger button is arranged approximately midway along a front face
of the housing.
[0014] In another preferred aspect, the present invention is a
method of collecting a sample of a body fluid. The method
preferably comprises forming an opening in a body tissue at a
sample site using a lancing device; applying compressive pressure
to the sample site with a portion of the lancing device; and
observing the sample site through a transparent portion of the
lancing device.
[0015] These and other objects, advantages, and features of the
present invention will become apparent upon reading the following
specification in conjunction with the accompanying drawing figures.
The advantages of the invention will be realized and attained by
means of the elements and combinations particularly pointed out in
the appended claims. It is to be understood that both the foregoing
general description and the following detailed description are
exemplary and explanatory of preferred embodiments of the
invention, and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of a lancing device according
to a preferred embodiment of the present invention.
[0017] FIG. 2 is a side view of the lancing device shown in FIG.
1.
[0018] FIG. 3 is a front view of the lancing device shown in FIG.
1.
[0019] FIG. 4 is an exploded view of the lancing device shown in
FIG. 1.
[0020] FIG. 5 is a detailed perspective view of a lancet carrier
portion of the lancing device shown in FIG. 1.
[0021] FIG. 6 is a perspective view of a stroke-control thumbwheel
portion of the lancing device shown in FIG. 1.
[0022] FIG. 7 is a plan view of the stroke-control thumbwheel
portion shown in FIG. 6.
[0023] FIG. 8 is a perspective view showing the underside of a
housing shell portion of the lancing device shown in FIG. 1.
[0024] FIG. 9 is a perspective view of the lancing device shown in
FIG. 1, with an endcap portion removed and a lancet installed.
[0025] FIG. 10 is a forward end view of the lancing device shown in
FIG. 1.
[0026] FIG. 11 is a sectional view of an endcap portion of the
lancing device shown in FIG. 1.
[0027] FIG. 12 shows a user cocking a lancing device according to a
preferred form of the present invention.
[0028] FIG. 13 shows a user lancing a forearm sampling site using a
lancing device according to a preferred form of the present
invention.
[0029] FIG. 14 shows a user lancing a fingertip sampling site using
a lancing device according to a preferred form of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0030] Example embodiments of the present invention are described
herein with reference to the drawing figures. It will be understood
that the described embodiments are by way of example only, and are
not intended to be exhaustive or limiting of the scope of the
claimed invention. It will also be understood that the various
features and embodiments described have individual utility as well
as utility in their various combinations thereof.
[0031] According to a preferred embodiment, and with particular
reference first to FIG. 1, the present invention comprises a
lancing device 10 for penetrating body tissue of a human or animal
subject to faciliate collection of a sample of a body fluid such as
blood or interstitial fluid. As seen with reference to FIG. 13, the
lancing device 10 is well suited for use in self-sampling from a
forearm sampling site 12 of the subject or, as seen with reference
to FIG. 14, from a fingertip sampling site 14 of the subject.
[0032] The lancing device 10 preferably comprises an exterior
housing 16 having a housing geometry configured for ease of use,
even by users suffering from impaired dexterity or eyesight. As
described herein, the housing 16 includes the overall outer
envelope of the lancing device 10 and, in an example embodiment
described in greater detail below, comprises an endcap and front
and back housing shells. The housing geometry preferably comprises
a length L defined between a forward end 20 and a rear end 22, a
width W defined between a first side 24 and a second side 26, and a
thickness t defined between a front 28 and a back 30. In preferred
form, the housing 16 is generally symmetric about perpendicular
first and second central planes of symmetry 32, 34, and the stroke
of a lancet carried by the lancing device 10 extends generally
linearly along a central axis defined by the intersection of the
first and second central planes of symmetry 32, 34. In preferred
form, the overall length L is less than four times, and more
preferably less than three times the overall width W. This aspect
ratio (i.e., L/W) of no more than 4:1, and more preferably no more
than 3:1, provides the lancing device 10 with improved stability in
use, which is of particular benefit in enabling users with impaired
dexterity to apply pressure between the forward end 20 and a
sampling site. According to preferred form, the overall width W of
the lancing device 10 is at least 11/2 times, and more preferably
about twice the overall thickness t. This transverse ratio (W/t) of
at least 3:2, and more preferably about 2:1, provides an easy to
grip device which resists twisting about the central axis. As used
herein, "overall" dimensions refer to dimensions of the main
portion of the housing, not including any irregular portions such
as sharp projections or recesses therefrom or therein. The rear end
22 preferably comprises a generally flat rear panel without edges
or sharp radii, generally perpendicular to the stroke of a lancet
carried by the lancing device 10, and preferably has a gradual
radius of curvature to generally conform to the palm, finger or
other portion of a human hand. The forward end 20 preferably also
comprises a generally flat forward panel oriented generally
perpendicular to the stroke of a lancet carried by the lancing
device 10. The housing 16 is preferably generally rectangular, and
its major exterior surfaces (e.g., the first and second sides, the
front, the back, and the forward and rear ends) are generally
perpendicular or parallel to the central axis. Edges at the
intersections of major surfaces are preferably radiused to provide
comfort in use. So configured, a user can easily apply pressure
sufficient for sampling, between the forward end 20 and a sampling
site, by applying compressive force to the rear end 22 in an axial
direction, while maintaining the device in a stable and upright
position, as shown for example in FIG. 13. In this manner, the
stroke of the lancet is oriented generally perpendicular to the
skin at the sampling site, to provide a straight in-straight out
lancing of the skin for improved user comfort. According to a
presently preferred form, the housing 16 has a maximum overall
length of about 100 mm, and is preferably between about 40 mm to
100 mm, and more preferably between about 80 mm to 90 mm. The
overall width is preferably at least about 25 mm, and more
preferably between about 30 mm to 35 mm, at the widest portion of
the housing. The overall thickness is preferably between about 10
mm to about 20 mm, and more preferably between about 15 mm to about
20 mm, at the thickest portion of the housing.
[0033] The lancing device 10 preferably further comprises a lancet
carrier 38 comprising means 40 for releasably engaging a standard
lancet 42, described with reference to FIGS. 2 and 3. The lancing
device 10 can be adapted for use with any of a number of
commercially available lancets, and the lancets will typically have
a needle diameter of between 30 gauge to 21 gauge, and more
preferably about 25 gauge, although smaller or larger gauge needles
may be suited for particular applications. The lancet carrier 38 is
preferably formed from plastic, metal or other substantially rigid
material(s), as by injection molding. In preferred form, the means
40 for releasably engaging a standard lancet 42 comprises a
resilient clamp having a first gripping jaw 44 and a second
gripping jaw 46 positioned in opposition to the first gripping jaw
to define a lancet-receiving channel therebetween. The first and
second gripping jaws 44, 46 are preferably movable between a closed
position for gripping a lancet 42, and an open position for
receiving and releasing the lancet 42 in a controlled manner. The
means 40 for releasably engaging a standard lancet 42 preferably
further comprises biasing means for biasing the first and second
gripping jaws 44, 46 toward the closed position. According to a
preferred embodiment depicted in the drawing figures, the first and
second gripping jaws 44, 46 comprise opposed portions of an
integrally formed split cylinder, and the biasing means comprises
an intact portion of the cylinder, or an integrally formed spline
48 connecting the first and second gripping jaws 44, 46.
Alternatively, the first and second gripping jaws 44, 46 can be
separately formed, and the biasing means can comprise interacting
portions of one or both jaws, and/or a separate biasing element
such as a spring. In order to provide ease of insertion of a lancet
42 between the first and second gripping jaws 44, 46, and
controlled release of the lancet therefrom, a first release arm 50
is provided, extending from the first gripping jaw 44, and a second
release arm 52 is provided, extending from the second gripping jaw
46. The first and second release arms 50, 52 are preferably
integrally formed with the first and second gripping jaws 44, 46,
or alternatively can be separately formed and attached. Outer
surface portions of the first and second release arms 50, 52 are
preferably knurled, grooved, or otherwise textured to form a
gripping surface. The first and second release arms 50, 52
preferably extend generally tangentially from the first and second
gripping jaws 44, 46, opposite the free ends of the gripping jaws
and beyond the biasing means, whereby application of force to the
first and second release arms 50, 52 moves the first and second
gripping jaws 44, 46 toward their open position for easy and
controlled insertion and release of a lancet 42. The knurled or
grooved gripping surfaces allow a user to squeeze the first and
second release arms 50, 52 together, as for example, between the
user's thumb and forefinger, for insertion and removal of a
lancet.
[0034] The lancet carrier 38 is preferably translationally mounted
to slide within the housing 16 for carrying a lancet 42 along a
reciprocating stroke from a retracted position wherein the lancet
is substantially entirely within the housing, through a cocked
position, to an extended position wherein at least a
tissue-penetrating portion 56 of the lancet extends a distance
outwardly beyond the housing, and back to the retracted position.
The lancing device 10 preferably further comprises a cocking
mechanism for shifting the lancet carrier from the retracted
position to the cocked position, driving means for driving the
lancet 42 from the cocked position to the extended position, and
retraction means for returning the lancet carrier from the extended
position to the retracted position. The driving means for driving
the lancet 42 from the cocked position to the extended position
preferably comprises a compression spring 60 engaged between a post
62 extending from a back housing shell 64 and a partition 66 of the
lancet carrier 38. The compression spring 60 biases the lancet
carrier 38 toward its extended position, and serves to propel the
lancet carrier along a tissue-penetration portion of its stroke.
The lancet carrier 38 preferably comprises one or more rails 68
adapted to slide in engagement with one or more fins 70 formed on
the interior face of the back housing shell 64, and the post 62
extends through a slot 72 in the lancet carrier 38, thereby
constraining the lancet carrier to slide generally linearly
parallel to the central axis of the housing 16. The interior
surface of a front housing shell 74 preferably comprises a channel
76 for engaging a cooperating rib 78 of the lancet carrier 38 to
guide the lancet carrier 38 along a generally linear stroke. Upon
assembly, the front and back housing shells 74, 64 are coupled, as
by crush pins, fasteners, adhesive, or other attachment means, and
the lancet carrier 38 is preferably constrained therebetween to a
well-guided, generally linear stroke along or adjacent the central
axis of the housing 16, whereby the lancet is driven along a
straight in-straight out path, penetrating the skin of the sampling
site at an angle generally perpendicular to the skin surface.
[0035] The cocking mechanism arms the lancing device 10 by placing
the spring 60 into compression, storing potential energy which is
converted to kinetic energy as the lancet is driven through the
tissue-penetrating portion of its stroke. The cocking mechanism is
preferably actuated by the user by grasping a cocking actuator 80
adjacent the rear end 22 and pulling the cocking actuator away from
the housing 16, as shown in FIG. 11. In a preferred embodiment, the
cocking actuator comprises first and second halves 80a, 80b, that
are attached to opposite sides of a cocking carriage 82 by pin
connections. The cocking carriage 82 slides between opposed
partitions 84, 86 of the back housing shell 64, and includes a pair
of shoulders 88, 90 for abutting the ends of the partitions to
limit the traverse of the cocking carriage 82. One or more lips 92
are preferably formed adjacent the rearward end of the lancet
carrier 38, and project over an edge 94 of the cocking carriage 82,
whereby retraction of the cocking carriage as shown in FIG. 11
draws the lancet carrier rearward into a cocked position in which
the spring 60 is compressed. As the lancet carrier 38 is drawn into
its cocked position, the tip of a cantilevered retaining finger 100
rides over an inclined ramp 102 formed on the interior surface of a
front housing shell 74, as shown in FIG. 10. The retaining finger
100 flexes as it passes over the ramp 102, and snaps to rest on an
upper surface of the ramp to retain the lancet carrier 38 in its
cocked position until released by the triggering mechanism
described below.
[0036] A return spring 106 is preferably coupled between a first
retaining lug 108 on the cocking carriage 82 and a second retaining
lug 110 on the lancet carrier 38, to draw the cocking actuator 80
back against the housing 16 after the lancing device is cocked. The
return spring 106 also serves to retract the lancet carrier from
its extended position to its retracted position after triggering
the device, thereby withdrawing the tissue-penetrating portion 56
from the tissue of the sampling site to minimize any pain
experienced by the subject. As will be understood by those skilled
in the art, the compression spring 60 is relatively stiffer than
the return spring 106 so that upon triggering the device, the
compression spring drives the lancet carrier 38 through its entire
stroke, from the cocked position to the extended position, before
the return spring withdraws the lancet carrier. The return spring
106 is preferably an expansion spring, rather than a compression
spring, whereby the return spring returns the lancet carrier to its
retracted position without significant oscillation. By
appropriately balancing the spring 60 and the return spring 106, a
smooth and quick stroke of the lancet carrier is achieved, and
oscillation of the lancet carrier is minimized to ensure that the
used experiences only a single stick by the lancet.
[0037] The lancing device 10 preferably further comprises a
triggering mechanism for releasing the lancet carrier 38 from its
cocked position. A trigger button 120 is preferably mounted on the
front 28 of the housing 16, and includes one or more retaining
clips 122 and a triggering pin that extends through the front
housing shell 74 adjacent the upper surface of the ramp 102. A
large trigger button 120 is preferably provided for ease of use,
and preferably extends across substantially the entire width of the
front face of the housing 16. For example, in an embodiment of the
device having a housing width of about 30 mm, a trigger button 120
about 20 mm wide is provided. The trigger button is preferably
arranged generally centrally along the front 28 of the housing,
approximately midway between the forward end 20 and the rear end
22, where a user can easily trigger the device while pressing the
forward end of the device against a sampling site. For example, in
an embodiment of the device having a housing length of about 87 mm,
the trigger button 120 is located about 40 mm from the forward end
20. The size and orientation of the trigger button, in combination
with the above-described transverse ratio of the housing, have been
found to provide superior ergonimics and ease of use, as the
trigger button is within easy reach of a user's thumb or finger in
a variety of gripping positions. The back 30 opposite the trigger
button 120 preferably comprises a generally broad, flat panel, so
that a user can easily and comfortably grip the device, as between
a thumb and forefinger, to depress the trigger button 120 with
his/her thumb. The front housing shell 74 preferably includes a
trigger recess 124 for receiving the trigger button 120. A spring
126 is preferably provided to bias the trigger button 120
outwardly. When the device is cocked and the tip of the retaining
finger 100 is engaged against the upper surface of the ramp 102 to
hold the lancet carrier 38 in its cocked position, the tip of the
retaining finger presses against the triggering pin. When the user
presses the trigger button 120, the triggering pin disengages the
retaining finger from the upper surface of the ramp, releasing the
lancet carrier 38, which is then driven by the compression spring
60 through the tissue-penetrating portion of its stroke to the
extended position, whereupon the return spring 106 then retracts
the lancet carrier 38 to its retracted position.
[0038] The lancing device 10 preferably further comprises stroke
control means for controlling the stroke range, and thereby
controlling the depth of penetration of the tissue penetration
portion 56 of the lancet 42 into the body tissue of the sampling
site. The stroke control means preferably comprises a limit member
140 attached to or comprises a portion of the lancet carrier 38,
and a stop 142 attached to the housing 16. Contact between the
limit member 140 and the stop 142 limits the range of the stroke of
the lancet carrier 38 in the forward direction, and defines the
extended position of the lancet carrier. In preferred form, the
stroke control means is adjustable to permit the user to
selectively adjust the stroke range and thereby varying the depth
of penetration of the tissue penetration portion 56 of the lancet
42 into the body tissue of the sampling site. In preferred form, a
selectively movable stop 142 permits the user to adjust the stroke
range by varying the position at which the limit member 140
contacts the stop 142 to stop the forward travel of the lancet
carrier 38. According to a preferred embodiment understood best
with reference to FIGS. 2, 8 and 9, the stroke adjustment means
comprises a thumbwheel 144 rotatably mounted to the housing 16. As
used herein, the term "thumbwheel" includes rotating dials or other
elements, translating slide mechanisms, or other movable stop
mechanisms, that are manipulable in any way by the user, and
specifically is not limited to elements manipulable by the thumb of
a user or by any particular body part of the user. A central
opening 146 in the thumbwheel 144 preferably receives a split-ring
axle 148 on the front housing shell 74, whereby the axis of
rotation of the thumbwheel is not aligned with, and more preferably
is generally perpendicular to, the central axis of the housing.
Alternatively, a solid ring axle can be provided. The thumbwheel
144 preferably carries the stop 142, and the stop 142 comprises an
eccentric contact surface, whereby rotation of the thumbwheel
varies the point of contact by the limit member 140, forward and
rearward in the direction of the central axis of the housing, to
limit the range of the stroke of the lancet carrier 38 in the
forward direction. For example, as seen in FIG. 9, the stop 142
comprises an eccentric surface that spans an arc .alpha. of
approximately 30.degree. to 50.degree. along the thumbwheel, and is
eccentrically offset approximately 2 mm. In this manner, selective
rotation of the thumbwheel 144 by the user through the span of the
arc .alpha. a varies the depth of penetration of the tissue
penetration portion 56 of the lancet 42 from a depth of
approximately 0.025 inch to approximately 0.100 inch.
Alternatively, the thumbwheel can comprise an eccentric surface
spanning an arc of less than 30.degree. or more than 50.degree.. By
directly controlling the stroke range, the present invention
reduces tolerance stacking and provides more consistent control of
the penetration depth than some previously known devices that use
interchangeable or screw-adjusted end caps for control of
penetration depth. The thumbwheel 144 is preferably mounted
generally midway along the length of the housing 16. A ribbed,
knurled, or otherwise textured edge portion 150 of the thumbwheel
144 preferably projects from one or both of the first and second
sides 24, 26, to facilitate depth adjustment. A portion of the
side(s) of the housing 16 may be recessed to permit access to the
thumbwheel for adjustment, while shielding the thumbwheel against
inadvertent contact during use of the device.
[0039] The lancing device 10 preferably further comprises a depth
indicator for indicating the set stroke range and, correspondingly,
the depth of penetration of the tissue penetration portion 56 of
the lancet 42 into the skin. According to a preferred embodiment,
the depth indicator comprises indicia 152 on the thumbwheel 144,
and a cooperating opening or window 154 through the housing for
displaying the indicia. In still further preferred embodiments, the
stroke adjustment means of the lancing device 10 further comprises
indexing means for allowing the user to increment the forward
extent of the stroke range, and accordingly the penetration depth,
through a plurality of discrete positions. In preferred form, the
indexing means comprises an arcuate series of detents 156 on the
interior of the front housing shell 74, and one or more cooperating
projections 158 formed on the thumbwheel 144. Rotation of the
thumbwheel 144 causes the projection(s) 158 to ride over the series
of detents 156, providing tactile feedback to the user.
[0040] The present invention preferably further comprises a lancing
device 10 having a pressure applicator for tensioning skin at the
sample site through the application of compressive pressure against
the sample site, and for stimulating the generation of a sample of
body fluid of a desired quantity. In preferred form, the pressure
applicator portion of the lancing device is adjacent or surrounds
the path of the tissue penetrating portion 56 as the lancet
traverses its stroke toward the extended position. In this manner,
the lancing device need not be repositioned for pressure
application after the tissue is pierced. The pressure applicator
preferably comprises a forward panel 170 adjacent or forming the
forward end 20 of the housing 16. In preferred form, the forward
panel 170 comprises the forward end of an end cap 172 that is
releasably attached to the forward ends of the assembled front and
back housing shells 74, 64. The endcap 172 is shown attached in
FIG. 1, and detached in FIG. 9. The forward panel 170 preferably
defines an opening 174 therethrough, for allowing passage of at
least the tissue penetrating portion 56 of a lancet 42 towards its
extended position. A raised lip 176 preferably projects a distance
forward from the forward panel, and surrounds at least a portion of
the opening 174. In preferred form, the opening 174 is between
about 4 mm to 8 mm in diameter. More preferably, the opening 174 is
less than about 6mm in diameter, so that a standard lancet will not
pass therethrough, thereby reducing the risk that the lancet will
be released from containment within the end cap 172. An opening
diameter of about 6 mm is presently considered to provide superior
sample collection results, while preventing release of the lancet.
The raised lip 176 preferably comprises an annular ring surrounding
the opening 174, and projects forward from the forward panel 170 a
distance of between about 1 mm to 3 mm, and most preferably about 2
mm. The annular ring preferably presents a generally forward-facing
annular land about 2 mm across. The disclosed dimensions of the
opening 174 and the raised lip 176 have been found to produce
surprisingly superior results in stimulating sample generation
without undue discomfort or bruising to the subject, and without
leaving appreciable compression marks on the skin surrounding the
sampling site, when used according to the sampling procedures
herein described. In particular, it is believed that the provision
of the generally flat forward panel 170 reduces discomfort to the
user by distributing compressive pressure over a larger surface
area at the sampling site and limiting the extent to which the
raised lip 176 may compress the skin and underlying tissue at the
sampling site. The provision of a raised lip 176 having the stated
dimensions, and provided with the above-described annular land,
further limits the depth of compression and reduces user discomfort
that might result from compression with a sharper contact
surface.
[0041] The present invention preferably further comprises a lancing
device 10 having a transparent portion adjacent the forward end 20
to permit the subject to visually observe the size of a drop of
blood or other fluid sample being collected. In a preferred
embodiment, the entire end cap 172 is formed from a transparent
material such as a clear plastic. Alternatively, the transparent
portion comprises a wall or window of transparent material or a
view hole or opening provided in an otherwise translucent or opaque
portion of the end cap 172 or other portion of the housing 16. The
transparent portion is positioned to permit observation of the
sample site through the opening 174 after the tissue penetrating
portion 56 has pierced the tissue of the sample site. The
combination of the transparent portion with the adjacent pressure
applicator described above advantageously permits the user to
observe the sampling site and monitor the sample size as pressure
is applied to stimulate sample generation. In a further preferred
embodiment, sample size indicia 180 are provided adjacent the
opening 174, most preferably on the interior surface of the forward
panel 170, to provide a size reference for comparison with the size
of the drop of blood or other fluid sample being collected. In an
example embodiment, the sample size indicia 180 is a circular mark
having a diameter equal to the diameter of a blood drop of the
requisite fluid volume required for analysis using a standard blood
glucose testing system.
[0042] The present invention further comprises a method of
collecting a sample of a body fluid. The method of the present
invention preferably comprises forming an opening in a body tissue
such as skin at a sample site of the tissue; using a lancing
device. In preferred form, the lancing device comprises a lancet
having a tissue penetrating portion, a pressure applicator, and a
transparent portion, substantially as described herein. For
example, with reference to the above-described lancing device 10,
the step of forming an opening in a body tissue can comprise:
removing an end cap 172 from the lancing device; loading a lancet
between the jaws 44,46 of a lancet carrier 38; replacing the end
cap; adjusting the stroke control means to the desired depth of
penetration; cocking the lancing device; pressing the forward panel
170 against the forearm, finger or other sampling site; and
pressing the trigger button 120 to release the lancet carrier. The
lancet is driven from its cocked position to its extended position,
whereupon the tissue penetrating portion of the lancet forms an
opening in the tissue at the sampling site, and then is retracted
to its retracted position via the return spring 106. The opening
174 and raised lip 176 cooperate to tension the skin at the
sampling site during and after the penetration of the tissue. Thus,
it may be preferable to apply slight or moderate compressive
pressure to the sampling site with the pressure applicator prior to
the lancet stick, to pre-tension the skin at the sampling site and
cause skin at the sampling site to bulge into the opening 174.
Alternatively, the forward end of the device can be placed in light
contact with the sampling site prior to the lancet stick, and
increased pressure applied after the stick. The method of the
present invention preferably further comprises applying compressive
pressure after the puncture to the sampling site with a pressure
applicator portion of the lancing device to stimulate the flow of a
body fluid such as blood through the opening in the tissue at the
sampling site. The opening 174 and raised lip 176 tension the
tissue to open the wound and generate a flow of body fluid. Steady
compressive pressure or varying compressive pressure, as by pumping
the device against the sampling site, can be applied. As pressure
is applied, the sample site is preferably observed through a
transparent portion of the lancing device. If a sample size indicia
is provided, the collected sample of body fluid is monitored in
comparison to the sample size indicia. When the collected sample
grows to the requisite size, the device is removed from the sample
site. Removal of the pressure applied by the device allows the
wound to close, facilitating faster clotting and healing, and
reducing or eliminating the extent of any residual bleeding that
could stain the user's clothing. The collected sample of body fluid
is then subjected to analysis according to any of a variety of
analytic techniques.
[0043] While the invention has been disclosed in preferred forms,
it will be apparent to those skilled in the art that many
modifications, additions, and deletions may be made therein without
departing from the spirit and scope of the invention as set forth
in the following claims.
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