U.S. patent application number 10/732615 was filed with the patent office on 2004-06-24 for sampling devices and methods utilizing biased capillary action.
Invention is credited to Roe, Steven N..
Application Number | 20040122339 10/732615 |
Document ID | / |
Family ID | 32713063 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040122339 |
Kind Code |
A1 |
Roe, Steven N. |
June 24, 2004 |
Sampling devices and methods utilizing biased capillary action
Abstract
A device is constructed so as to define a capillary channel that
draws a body fluid form a proximal portion of the capillary channel
toward a distal portion. A counterbore defining a "ledge" not
substantially normal to the center line of channel causes the
meniscus of body fluid to be "biased" into a non-radially-symmetric
shape. In one example, the bias draws the body fluid toward a
testing element that is set into a groove in the main body of the
device. In another example, hydrophilic and/or hydrophobic regions
are created on or in device to produce the biasing effect. In
certain configurations, device requires less blood to be drawn into
the capillary channel for a successful test than if the biasing
effect were not created.
Inventors: |
Roe, Steven N.; (San Mateo,
CA) |
Correspondence
Address: |
Woodard, Emhardt, Moriarty, McNett & Henry LLP
Bank One Center/Tower
Suite 3700
111 Monument Circle
Indianapolis
IN
46204-5137
US
|
Family ID: |
32713063 |
Appl. No.: |
10/732615 |
Filed: |
December 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60436331 |
Dec 24, 2002 |
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Current U.S.
Class: |
600/573 ;
600/583 |
Current CPC
Class: |
A61B 5/150358 20130101;
A61B 5/150022 20130101 |
Class at
Publication: |
600/573 ;
600/583 |
International
Class: |
A61B 005/00 |
Claims
What is claimed is:
1. A device comprising a main body that defines a capillary
channel, wherein: said capillary channel is dimensioned to draw a
body fluid into said capillary channel by capillary action; said
body fluid defines a meniscus when said body fluid is drawn into
said capillary channel; and said capillary channel is constructed
to tend to bias said meniscus in a radially asymmetric manner when
said body fluid is drawn into said capillary channel.
2. The device of claim 1 wherein said bias tends to bias said fluid
toward a testing element in spatial communication with said
fluid.
3. The device of claim 2 wherein said testing element comprises a
test strip.
4. The device of claim 3 wherein said test strip comprises a
membrane.
5. The device of claim 3 wherein said test strip is mounted in a
groove defined in said device.
6. A device for sampling body fluid, comprising a main body that
defines a capillary channel, wherein: said capillary channel is
dimensioned to draw a body fluid into said capillary channel by
capillary action; said body fluid defines a meniscus when said body
fluid is drawn into said capillary channel; and said capillary
channel has a relatively hydrophilic portion tending to bias said
meniscus in a radially asymmetric manner when said body fluid is
drawn into said capillary channel.
7. The device of claim 6 wherein said bias tends to bias said fluid
toward a testing element in spatial communication with said
fluid.
8. The device of claim 7 wherein said testing element comprises a
test strip.
9. The device of claim 8 wherein said test strip comprises a
membrane.
10. The device of claim 8 wherein said test strip is mounted in a
groove defined in said device.
11. A fluid sampling device comprising a capillary tube defining a
capillary channel adapted to contain fluid defining a meniscus, the
capillary channel further adapted to impart a radially asymmetric
bias to the meniscus of the fluid when the fluid is within the
capillary channel.
12. The device of claim 11, the capillary channel having an angled
counterbore adapted to impart the radially asymmetric bias to the
meniscus of the fluid when the fluid is within the capillary
channel.
13. The device of claim 12, wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
14. The device of claim 13, wherein said testing element comprises
a test strip.
15. The device of claim 14, wherein said test strip comprises a
membrane.
16. The device of claim 14, wherein said test strip is mounted in a
groove defined in said device.
17. The device of claim 11, the capillary channel having a
hydrophilic region adapted to impart the radially asymmetric bias
to the meniscus of the fluid when the fluid is within the capillary
channel.
18. The device of claim 17, wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
19. The device of claim 18, wherein said testing element comprises
a test strip.
20. The device of claim 19, wherein said test strip comprises a
membrane.
21. The device of claim 19, wherein said test strip is mounted in a
groove defined in said device.
22. A device, comprising: a body defining a capillary channel
having a first region and a second region and a proximal portion
and a distal portion; the first region having a first capillary
attraction to a fluid when the fluid flows in the capillary channel
from the proximate portion toward the distal portion; the second
region having a second capillary attraction to the fluid when the
fluid flows in the capillary channel from the proximate portion
toward the distal portion; and the first capillary attraction being
stronger than the second capillary attraction sufficiently to bias
the flow of the fluid within the capillary channel toward the first
region when the fluid flows in the capillary channel from the
proximate portion toward the distal portion.
23. The device of claim 22 wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
24. The device of claim 23, wherein said testing element comprises
a test strip.
25. The device of claim 24, wherein said test strip comprises a
membrane.
26. The device of claim 24, wherein said test strip is mounted in a
groove defined in said device.
27. A fluid sampling device comprising body means defining
capillary channel means, wherein the capillary channel means
includes means for biasing the meniscus of fluid within the
capillary channel means.
28. The device of claim 27, wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
29. The device of claim 28, wherein said testing element comprises
a test strip.
30. The device of claim 29, wherein said test strip comprises a
membrane.
31. The device of claim 29, wherein said test strip is mounted in a
groove defined in said device.
32. A device for sampling body fluid, comprising: a body defining a
capillary channel; and a lancet disposed within said capillary
channel and defining a space between said lancet and said body;
said lancet being selectively advancable and retractable; said
capillary channel being dimensioned to draw a body fluid into said
space through capillary action; said body fluid defining a meniscus
when said body fluid is drawn into said space; and said capillary
channel, or said lancet, or both, being dimensioned to tend to bias
said meniscus in a radially asymmetric manner when said body fluid
is drawn into said space.
33. The device of claim 32, wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
34. The device of claim 33, wherein said testing element comprises
a test strip.
35. The device of claim 34, wherein said test strip comprises a
membrane.
36. The device of claim 34, wherein said test strip is mounted in a
groove defined in said device.
37. A device for sampling body fluid, comprising: a body defining a
capillary channel; and a lancet disposed within said capillary
channel and defining a space between said lancet and said body;
said lancet being selectively advancable and retractable; said
capillary channel being dimensioned to draw a body fluid into the
space through capillary action; said body fluid defining a meniscus
when said body fluid is drawn into the space; and said capillary
channel, or said lancet, or both, having a relatively hydrophilic
portion tending to bias said meniscus toward said hydrophilic
portion when said body fluid is drawn into the space.
38. The device of claim 37, wherein said bias tends to bias said
fluid toward a testing element in spatial communication with said
fluid.
39. The device of claim 38, wherein said testing element comprises
a test strip.
40. The device of claim 39, wherein said test strip comprises a
membrane.
41. The device of claim 39, wherein said test strip is mounted in a
groove defined in said device.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/436,331, filed Dec. 24, 2002 (Attorney Docket
No. 7404-453), which is hereby incorporated by reference in its
entirety.
BACKGROUND
[0002] The present invention generally relates to the medical
field, and more specifically, but not exclusively, relates to the
sampling of bodily fluids.
[0003] The acquisition and testing of body fluids is useful for
many purposes, and continues to be of importance for use in medical
diagnosis and treatment, and in other diverse applications. In the
medical field, it is desirable for lay operators to perform tests
routinely, quickly and accurately outside of a laboratory setting,
with rapid results and a read-out of the resulting test
information. Testing can be performed on various body fluids, and
for certain applications, it is particularly related to testing of
blood and/or interstitial fluid. Such fluids can be tested for a
variety of characteristics of the fluid or analytes contained in
the fluid, in order to identify medical conditions, determine
therapeutic responses, assess progress of treatments and the
like.
[0004] A common medical test is the measurement of blood glucose
levels. The glucose level can be determined directly by analysis of
the blood, or indirectly by analysis of other fluids, such as
interstitial fluid. Diabetics are generally instructed to measure
their glucose levels several times a day, depending on the nature
and severity of their diabetes. Based upon observed patterns in the
measurement of glucose levels, the patient and physician can
determine the appropriate level of insulin to be administered, also
taking into account such issues as diet, exercise and other
factors.
[0005] In testing for the presence of analytes such as glucose in a
body fluid, test systems are commonly used which take advantage of
oxidation/reduction reaction, which occurs using an
oxidase/peroxidase detection chemistry. The testing reagent is
exposed to a sample of the body fluid for a suitable period of
time, and there is a color change if analyte (glucose) is present.
Typically, the intensity of the change is proportional to the
concentration of analyte in the sample. The color of the reagent is
then compared to a known standard, which enables one to determine
the amount of analyte present in the sample. This determination can
be made, for example, by visual check or by an instrument, such as
a spectrophotometer at a selected wave length, or a blood glucose
meter. Electrochemical and other systems are also well known for
testing body fluids for properties of constituents. Typically, a
fingertip or some other body location of a patient is lanced with a
lancet in order to obtain a body fluid sample.
[0006] Although fingertips generally provide an ample supply of
blood, repeated lancing of fingertips can be quite painful due to
the high concentration of nerve endings in the fingertips.
Therefore, there has been a trend towards sampling fluids from
alternate sites on the body, where the nerve concentrations are
lower, such as the forearm. As should be appreciated, since
alternate sites have lower nerve concentrations, the patient
experiences less pain when lancing the alternate site. However,
these alternate sites usually produce less fluid as compared to
fingertips. Consequently, it has been a goal to reduce the amount
of fluid needed for a successful test. To achieve this goal, it is
desirable to ensure that as much fluid as possible is transported
from the incision to the test area so as to minimize waste.
[0007] Thus, there remains a need for improvement in this
field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an isometric view of a portion of an example
apparatus according to the present invention.
[0009] FIG. 2A is an end view of the apparatus of FIG. 1.
[0010] FIG. 2B is a side view of the apparatus of FIG. 1.
[0011] FIG. 2C is a cross-sectional view taken along line 2C-2C of
FIG. 2B.
[0012] FIG. 3 is a side view of the apparatus of FIG. 1 disposed
above body fluid on a tissue surface.
[0013] FIG. 4 is a side view illustrating the apparatus of FIG. 1
displaying the initial capillary action.
[0014] FIG. 5 is a side view illustrating the apparatus of FIG. 1
displaying biased capillary action.
[0015] FIG. 6 is a side view of a portion of an alternative example
apparatus according:to the present invention displaying another
form of biased capillary action.
[0016] FIG. 7 is a side view of the apparatus of FIG. 6
illustrating a test strip disposed within a groove in the
apparatus.
[0017] FIG. 8 is a side view of a portion of another alternative
example apparatus according to the present invention.
[0018] FIG. 9 is a side view of the apparatus of FIG. 8 displaying
another form of biased capillary action.
[0019] FIG. 10 is a side view of the apparatus of FIG. 8
illustrating a test strip disposed within a groove in the
apparatus.
[0020] FIG. 11 is a side view of a portion of yet another
alternative example apparatus according to the present
invention.
[0021] FIG. 12 is an isometric view of a portion of another example
apparatus according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] Provided below is a written description of examples
embodying the invention and examples of making and using the same.
The scope of the invention is not limited to these examples, but
rather is defined solely by the numbered claims that appear at the
end of this document, and the invention includes alterations,
modifications, and further applications that fall within the
claims. The written description uses full, clear, concise, and
exact terms to enable any person skilled in the art to which the
invention pertains to make and use the invention. The best mode
contemplated by the inventor of carrying out the invention is also
set forth herein.
[0023] All the information set forth in the following patent
applications is incorporated by reference, as if fully set forth
herein: U.S. patent application Ser. No. 10/054,270, filed Jan. 22,
2002, entitled LANCET DEVICE HAVING CAPILLARY ACTION; and U.S.
patent application Ser. No. 10/165,101, filed Jun. 7, 2002,
entitled SAMPLING DEVICES AND METHODS UTILIZING A HORIZONTAL
CAPILLARY TEST STRIP.
[0024] The present invention generally concerns a sampling device
that is configured to bias the flow of body fluid in the device so
as to reduce the amount of fluid needed for sampling. In one
embodiment, the device has a capillary channel that is structured
to bias a miniscus of the fluid in a radially asymmetric manner.
Specifically, the capillary channel has an angled counter bore that
biases the meniscus of the fluid in a radial asymmetric manner. In
another embodiment, the capillary channel includes hydrophobic and
hydrophillic portions that bias the flow of fluid.
[0025] FIG. 1 illustrates one example of a device 100 for sampling
body fluid (not shown), comprising a main body 110 defining a
capillary channel 120. The capillary channel 120 is preferably
dimensioned to draw a body fluid into the capillary channel 120
through capillary action, as described more fully in the
above-incorporated patent applications. In this example the
capillary channel 120 is further dimensioned to form an angled
counterbore 130.
[0026] Though the device 100 is shown in FIG. 1 as cylindrical with
an annular cross-section, this is just one example geometry. Any
geometry can be used for device 100, as long as device 100 provides
a capillary channel 120 dimensioned to draw a body fluid into said
capillary channel 120 through capillary action. For example, one or
more portions of device 100 and/or capillary channel 120 could
independently have square, rectangular, triangular, oval, U-shaped,
amorphous, or any other shape cross-sections. Device 100 may
comprise any material and may be made by any means, such as the
materials and methods of manufacture set forth in the
above-incorporated patent applications.
[0027] FIGS. 2A, 2B and 2C further illustrates the example of FIG.
1. The device, or apparatus, 100 comprises a body 110 defining a
capillary channel 120 having a first region 140 and a second region
150 and a proximal portion 160 and a distal portion 170. In the
example shown in FIGS. 1-5, the second region 150 of the capillary
channel 120 defines a counterbore 130 ending in a surface
non-normal to the longitudinal axis 180 of the capillary channel
120 by angle .alpha..
[0028] FIG. 3 illustrates the device 100 positioned above a drop of
body fluid 310 issuing from an incision 305 in body tissue 300. The
body fluid 310 may be produced by puncturing the body tissue 300,
or by any other means, including as described in the
above-incorporated patent applications. FIG. 4 illustrates the
device 100 lowered toward the body tissue 300 until the proximal
portion 160 of the capillary channel 120 is in fluid communication
with the body fluid 310. The body fluid 310 is then drawn into the
capillary channel 120 by capillary action, as represented in FIGS.
4 and 5. As shown in FIGS. 4 and 5, the body fluid 310 flows in the
capillary channel 120 from the proximal portion 160 toward the
distal portion 170. However, when the body fluid 310 reaches the
angled counterbore 130, the meniscus 320 of the body fluid 310 is
biased radially asymmetrically about the centerline 180 toward one
side of capillary channel 120, as shown in FIG. 5.
[0029] Capillary mechanics dictate that the step or offset created
by the angled counterbore 130 causes the first region 140 to have
an effectively stronger capillary attraction to body fluid 310 than
the second region 150 when the body fluid 310 flows in the
capillary channel 120 from the proximal portion 160 toward the
distal portion 170. Though an angled counterbore 130 is shown as an
example, any geometry including a step or other shape can be used
that has the capillary biasing effect of biasing the forces of
capillary action acting on body fluid 310 so that they are radially
asymmetric about the centerline 180, such as by tending to favor
one side of capillary channel 120.
[0030] This difference in capillary attraction pulls or biases the
meniscus 320 radially asymmetrically about the centerline 180,
toward the first region 140 and away from the second region 150,
thus biasing the body fluid 310 toward a first side 122 of the
capillary channel 120, and away from a second side 124 of the
capillary channel 120. Subject to the materials and dimensions used
in device 100 and their interaction with a particular body fluid
310, increasing the angle .alpha. tends to increasingly bias the
body fluid 310 toward a first side 122 of the capillary channel
120, and away from a second side 124 of the capillary channel
120.
[0031] FIG. 6 shows a device 100' that is similar to device 100,
but has a counterbore 130' with an increased angle .alpha.'. As
shown in FIG. 6, increasing the angle from .alpha. to .alpha.'
tends to increase the bias of the meniscus 320 radially
asymmetrically about the centerline 180, thus tending to increase
the bias of the body fluid 310 toward a first side 122 of the
capillary channel 120, and away from a second side 124 of the
capillary channel 120.
[0032] FIG. 7 shows the device 100' of FIG. 6 further including a
testing element 700 disposed within a groove 710 in the main body
110' of the device 100". When body fluid 310 has moved up first
side 122, as shown, the testing element 700 is in spatial
communication with body fluid 310 through one or more passageways
720, so that the testing element 700 may be used to test various
aspects of the body fluid 310, for instance as described in the
above-incorporated patent applications. Testing element 700 may be
any testing means that interfaces with body fluid 310, such as a
test strip or other chemistry, for instance as described in the
above-incorporated patent applications.
[0033] Since the body fluid 310 tends to bias toward the first side
122 of the capillary channel 120, passageways 720 are shown formed
in the first side 122 of the capillary channel 120. Passageways 720
are filled with body fluid 310, even though the adjacent portion of
the capillary channel 120 is only partially filled with body fluid
310 due to the biasing effect described above. Thus, the device
100" is capable of communicating body fluid 310 to testing element
700 using less body fluid 310 than would be required without the
capillary biasing effect described herein.
[0034] FIG. 8 illustrates another example device 100" configured to
create a capillary biasing effect without requiring an angled
counterbore 130 or any geometry such as a step or other shape in
the capillary channel 120. Instead, the first side 122 of the
capillary channel 120 includes a hydrophilic region 800. The
hydrophilic region 800 is hydrophilic relative to one or more
adjacent regions of the capillary channel 120, such as the second
side 124. The hydrophilic region 800 need only be relatively
hydrophilic; for instance, the hydrophilic region 800 may be
defined by providing hydrophobic surrounding regions. A relatively
hydrophilic region 800 may be created by forming portions of the
capillary channel 120 from hydrophilic or hydrophobic materials, or
by treating portions to be relatively hydrophilic or hydrophobic,
for instance in the manners described in the above-incorporated
patent applications.
[0035] FIG. 9 illustrates the device 100" of FIG. 8 positioned near
body tissue 300 so that the proximal portion 160 of the capillary
channel 120 is in fluid communication with a small drop of body
fluid 310 issuing from an incision 305 in body tissue 300, the body
fluid 310 being drawn into the capillary channel 120 by capillary
action. When the body fluid 310 reaches the relatively hydrophilic
region 800, the body fluid 310 is disproportionately attracted to
the hydrophilic region 800. This difference in capillary attraction
pulls or biases the meniscus 320 radially asymmetrically about the
centerline 180, thus biasing the body fluid 310 toward the
relatively hydrophilic region 800 of the first side 122 of the
capillary channel 120, and away from the relatively hydrophobic
second side 124 of the capillary channel 120.
[0036] FIG. 10 shows the device 100" of FIG. 9 further including a
testing element 700 disposed within a groove 710 in the main body
110" of the device 100". The testing element 700 is in spatial
communication with body fluid 310 through one or more passageways
720, so that the testing element 700 may be used to test various
aspects of the body fluid 310, as set forth above. Since the body
fluid 310 tends to bias toward the hydrophilic region 800 on the
first side 122 of the capillary channel 120, passageways 720 are
shown formed in the first side 122 of the capillary channel 120.
Passageways 720 are filled with body fluid 310, even though the
adjacent portion of the capillary channel 120 is only partially
filled with body fluid 310 due to the biasing effect described
above. Thus, the device 100" is capable of communicating body fluid
310 to testing element 700 using less body fluid 310 than would be
required without the capillary biasing effect described herein.
[0037] FIG. 11 shows a device 100'" including by way of example
both an angled counterbore 130 and a relatively hydrophilic region
800 in the capillary channel 120, and further including an
integrated lancet 1100 for forming the incision 305. The integrated
lancet 1100, or any other structure, may be used in conjunction
with devices incorporating the capillary biasing effect described
herein. For instance, devices including an integrated lancet 1100
can include any or all of the structure set forth in the
above-incorporated patent applications. In this example, an angled
counterbore 130 works in conjunction with a relatively hydrophilic
region 800 to bias body fluid 310 toward testing element 700 using
less body fluid 310 than would be required without the capillary
biasing effect described herein.
[0038] FIG. 12 illustrates a capillary tube 1200 according to
another embodiment of the present invention. In the illustrated
embodiment, the capillary tube 1200 has a stepped-end counterbore
1202 for biasing the fluid in a specified direction inside the
capillary tube.
[0039] Various alternatives to the structures and details described
herein are available, and could be implemented without undue
experimentation by those skilled in the art. For example, a
plurality of sites on a testing device might be used for testing
the same or different characteristics of the body fluid. Those
sites might be spaced around the circumference of the device at
approximately the same distance from the proximal end, or they
might be situated at different distances from the proximal end.
They may be on the same side of the device, opposite sides of the
device, or in some other relative configuration.
[0040] Further, various test methods may be implemented at the one
or more test sites, including for example optical, magnetic, and
chemical tests as would occur to one skilled in the art given the
disclosure herein, which includes the matter incorporated by
reference above.
[0041] Furthermore, a wide variety of techniques might be used to
bias the body fluid toward the testing site(s). These techniques
might include (but are not limited to) the angled-end counterbore
and hydrophobic/hydrophilic wall techniques discussed above;
chemically treating or coating one or more portions of the inner
wall of the capillary tube with one or more different hydrophobic,
hydrophilic, or other chemicals known in the art; the stepped-end
counterbore 1202 as shown in FIG. 12; roughening the inner wall of
the capillary tube in one region relative to another; and forming
longitudinal grooves in certain portions of the inner wall (or more
grooves in certain portions than in others).
[0042] While examples embodying the invention have been illustrated
and described in detail in the drawings and foregoing description,
which includes material incorporated by reference, these examples
are illustrative and not restrictive in character, it being
understood that only certain examples have been shown and described
and that all changes and modifications that come within the spirit
of the invention are to be protected.
* * * * *