U.S. patent application number 15/643432 was filed with the patent office on 2017-10-26 for sensor and sensor system equipped with same.
The applicant listed for this patent is Panasonic Healthcare Holdings Co., Ltd.. Invention is credited to Hirofumi EZAKI, Akihisa HIGASHIHARA.
Application Number | 20170307559 15/643432 |
Document ID | / |
Family ID | 47356779 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170307559 |
Kind Code |
A1 |
EZAKI; Hirofumi ; et
al. |
October 26, 2017 |
SENSOR AND SENSOR SYSTEM EQUIPPED WITH SAME
Abstract
This sensor has a diverter, such as a convex portion and a
concave portion, on the side wall of a cavity. A biological sample
deposited in a suction opening is drawn into the cavity by
capillary action, but if the amount of biological sample is too
small, either the biological sample is prevented from moving
forward by the convex portion and the concave portion, or the time
it takes to reach a detecting electrode is increased, which
provides the user enough time to supply additional biological
sample before a false detection occurs.
Inventors: |
EZAKI; Hirofumi; (Ehime,
JP) ; HIGASHIHARA; Akihisa; (Ehime, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Healthcare Holdings Co., Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
47356779 |
Appl. No.: |
15/643432 |
Filed: |
July 6, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14123099 |
Nov 28, 2013 |
9733205 |
|
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PCT/JP2012/003787 |
Jun 11, 2012 |
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15643432 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/3272 20130101;
G01N 27/3277 20130101 |
International
Class: |
G01N 27/327 20060101
G01N027/327; G01N 27/327 20060101 G01N027/327 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2011 |
JP |
2011-134144 |
Claims
1. A sensor that is used in at least one of the detection and
quantification of a target substance contained in a biological
sample, said sensor comprising: a cavity including a side wall and
a back wall; a suction opening from an outside of the sensor to an
inside of the cavity; a working electrode disposed inside the
cavity; a counter electrode disposed inside the cavity; a detecting
electrode disposed inside the cavity, the detecting electrode
disposed toward the suction opening from the back wall and spaced
apart from the side wall of the cavity; a diverter including a
convex portion, the convex portion being a portion of the side
wall; and wherein the biological sample advances along a path from
the suction opening to the detecting electrode, the back wall has a
planar shape, the side wall is disposed so that the diverter is
configured to extend along the path from the suction opening to the
detecting electrode, and a width of the cavity is smaller than a
width of the path on a side of the back wall.
2. The sensor according to claim 1, further comprising: a
substrate; a spacer disposed on the substrate; and a cover disposed
on the spacer; the cavity further including: a bottom of the
cavity, the bottom of the cavity including the substrate, and a
ceiling of the cavity, the ceiling of the cavity including the
cover; and wherein the side wall includes the spacer, the working
electrode, the counter electrode, and the detecting electrode are
formed on the substrate, and the detecting electrode is disposed at
a position in the cavity furthest from the suction opening.
3. The sensor according to claim 2, wherein the convex portion is
formed on at least one of the bottom of the cavity and the ceiling
of the cavity.
4. A sensor system, comprising: a sensor according to claim 1; and
a measurement device configured to measure the concentration of a
target substance in a biological sample based on a current value
obtained from the sensor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of and claims
priority to U.S. application Ser. No. 14/123,099 filed on Nov. 28,
2013, which is a national stage filing under 35 U.S.C. .sctn.371,
and claims benefit of priority to PCT Application Number
PCT/JP2012/003787 filed on Jun. 11, 2012, which claims priority to
Japanese Patent Application No. 2011-134144 filed on Jun. 16, 2011.
The entire disclosures of U.S. application Ser. No. 14/123,099, PCT
Application Number PCT/JP2012/003787 and Japanese Patent
Application No. 2011-134144 are hereby incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a sensor used in the
detection and/or quantification of a target substance (such as
blood glucose) contained in a biological sample, and to a sensor
system equipped with this sensor.
BACKGROUND
[0003] Biological sample measurement devices that measure
biological data such as blood glucose level have been used in the
past. A sensor is mounted to a measurement device such as this
(hereinafter referred to simply as "sensor"). The sensor is
provided with a cavity and suction opening. When a biological
sample is deposited in the suction opening, the biological sample
is guided into the cavity by capillary action. A specific voltage
is applied to the sensor electrode in the measurement device, and
the output value from the output electrode is measured, thereby
acquiring information about the blood glucose level, etc.
[0004] With a sensor such as this, accurate measurement cannot be
performed unless the sample reaches the electrode disposed inside
the sensor.
[0005] In view of this, Japanese Laid-Open Patent Application
2003-004691 discloses an electrochemical sensor that outputs an
error signal if there is an insufficient sample containing the
substance to be analyzed, and that prompts the user to redo the
measurement.
SUMMARY
[0006] When taking user convenience into account, it is preferable
if the user can carry out measurement just by adding more of the
biological sample, rather than ending the measurement, particularly
if at first the user did not supply enough of the biological
sample.
[0007] However, if the length of time from when the sensor is
mounted to the measurement device until an error message is
displayed is extended in order to provide enough time to add more
biological sample, there will be situations in which the system
concludes that there is enough biological sample for measurement
despite the fact that the amount of biological sample is actually
insufficient for measurement.
[0008] This can happen for a number of reasons. One reason is due
to wicking, in which the biological sample moves along the inner
walls of the cavity and reaches the detecting electrode inside the
sensor. Another reason is if the biological sample seeps through to
the reagent layer, so that the biological sample reaches the
detecting electrode even though there is an insufficient amount of
biological sample for measurement.
[0009] It is an object of the present invention to provide a sensor
that prevents false detection caused by wicking, while allowing
measurement to continue by adding more biological sample even if an
insufficient amount of biological sample was added at first, and to
provide a measurement device equipped with this sensor.
[0010] The sensor pertaining a first embodiment is a sensor that is
used in the detection and/or quantification of a target substance
contained in a biological sample, said sensor comprising:
[0011] a cavity;
[0012] a suction opening that goes from the outside of the sensor
to the inside of the cavity;
[0013] an electrode provided inside the cavity; and
[0014] a diverter having at least one of a concave portion and a
convex portion, the at least one of a concave portion and a convex
portion being provided to the inner wall of the cavity.
[0015] With this sensor, a biological sample deposited in the
suction opening is drawn into the cavity by capillary action, but
if there is too little biological sample, either the biological
sample is prevented from moving forward by a convex portion and/or
a concave portion, or the time it takes to reach a detecting
electrode after the biological sample has been deposited is
increased.
[0016] Consequently, the diverter makes the path from the suction
opening to the electrode longer, so false detection of the
biological sample caused by wicking can be prevented. Furthermore,
this provides the user enough time to supply additional biological
sample before a false detection occurs.
[0017] The sensor pertaining to a second embodiment is a sensor
that is used in the detection and/or quantification of a target
substance contained in a biological sample, said sensor
comprising:
[0018] a cavity having a first end and a second end;
[0019] a suction opening that is provided at the first end of the
cavity and goes to the outside of the sensor; and
[0020] an electrode that is disposed closer to the second end than
to the first end inside the cavity,
[0021] wherein, if we let D1 be the distance from the first end to
the second end along the side wall of the cavity, and D2 be the
linear distance from the first end to the second end, the
relationship D1.gtoreq.1.05.times.D2 is satisfied, and preferably
the relationship D1.gtoreq.1.65.times.D2 is satisfied.
[0022] With this sensor, since the diverter makes the path from the
suction opening to the electrode longer, it takes any biological
sample that has moved along the inner wall longer to reach the
electrode.
[0023] The longer path prevents false detection, of the amount of
biological sample, caused by wicking. Furthermore, this provides
the user enough time to supply additional sample before a false
detection occurs.
[0024] With the present invention, if too little biological sample
is deposited, either the biological sample is prevented from moving
forward, or the time it takes for a false detection to occur after
the biological sample has been deposited is extended. This provides
the user enough time to supply more of the biological sample before
a false detection occurs.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is an exploded oblique view of a simplified
configuration of a sensor;
[0026] FIG. 2 is a cross section of a simplified configuration of a
sensor;
[0027] FIG. 3 is a plan view of a simplified configuration of a
sensor, in which a cover is not shown;
[0028] FIG. 4 is a plan view of one mode of the interior of the
sensor cavity;
[0029] FIG. 5 is a plan view of another mode of the interior of the
sensor cavity;
[0030] FIG. 6 is a plan view of yet another mode of the interior of
the sensor cavity;
[0031] FIG. 7 is a plan view of yet another mode of the interior of
the sensor cavity;
[0032] FIG. 8 is a plan view of yet another mode of the interior of
the sensor cavity;
[0033] FIG. 9 is a plan view of yet another mode of the interior of
the sensor cavity;
[0034] FIG. 10 is a plan view of yet another mode of the interior
of the sensor cavity;
[0035] FIG. 11 is a plan view of yet another mode of the interior
of the sensor cavity;
[0036] FIG. 12 is a plan view of yet another mode of the interior
of the sensor cavity;
[0037] FIG. 13 is a plan view of yet another mode of the interior
of the sensor cavity;
[0038] FIG. 14 is a plan view of yet another mode of the interior
of the sensor cavity;
[0039] FIG. 15 is a plan view of yet another mode of the interior
of the sensor cavity;
[0040] FIG. 16 is a plan view of yet another mode of the interior
of the sensor cavity;
[0041] FIG. 17 is a side view of yet another mode of the interior
of the sensor cavity;
[0042] FIG. 18 is a plan view of one mode of the interior of a
side-fill sensor;
[0043] FIG. 19 is a plan view of another mode of the interior of a
side-fill sensor;
[0044] FIG. 20 is an oblique view of the simplified configuration
of a sensor system; and
[0045] FIG. 21 is a block diagram of the simplified configuration
of a sensor system.
DETAILED DESCRIPTION
[0046] Selected embodiments will now be explained with reference to
the drawings. It will be apparent to those skilled in the art from
this disclosure that the following descriptions of the embodiments
are provided for illustration only and not for the purpose of
limiting the invention as defined by the appended claims and their
equivalents.
[0047] 1. Sensor
[0048] (1-1) A Simplified Configuration of the Sensor
[0049] A sensor 1 is an example of a sensor that is used in the
detection and/or quantification of a target substance contained in
a biological sample.
[0050] As shown in FIGS. 1 to 3, the sensor 1 comprises a substrate
2, a conductor layer 3, a reagent layer 4, a spacer 5, and a cover
6.
[0051] (1-2) Substrate
[0052] As shown in FIGS. 1 and 2, the substrate 2 is a flat member.
The substrate 2 has insulating properties. Examples of materials
that can comprise the substrate 2 include polyethylene
terephthalate, vinyl polymers, polyimide, polyester, styrenics, and
other such resins; glass; and ceramics.
[0053] There are no particular restrictions on the dimensions of
the substrate 2, but the width of the substrate 2, for example, is
preferably 3 to 20 mm, and more preferably 5 to 10 mm. The length
of the substrate 2 is preferably 10 to 40 mm. The thickness of the
substrate 2 is preferably 0.05 to 2 mm, and more preferably 0.1 to
1 mm. The width, length, and thickness of the substrate 2 are
preferably all within the above ranges.
[0054] (1-3) Conductor Layer
[0055] As shown in FIGS. 1 and 2, the conductor layer 3 is formed
on the substrate 2, and has a substantially uniform thickness. The
conductor layer 3 includes three electrodes 31 to 33. As shown in
FIG. 1, a portion of each of the electrodes 31 to 33 is disposed so
as to face a cavity 51.
[0056] As shown in FIG. 3, the electrode 32, the electrode 31, and
the electrode 33 are disposed in that order inside the cavity 51,
from a first end 53 to a second end 54 of the cavity 51. The
electrode 31 is sometimes called a working electrode, the electrode
32 a counter electrode, and the electrode 33 a detecting
electrode.
[0057] As will be discussed below, when the biological sample
reaches the working electrode 31 and the detecting electrode 33,
there is a change in the current value between the working
electrode 31 and the detecting electrode 33. A measurement device
101 (discussed below) detects from this change that a biological
sample has been deposited, and starts measurement. The measurement
device 101 can also use a change in the current value between the
working electrode 31 and the counter electrode 32 to measure the
concentration of a target substance in the biological sample.
[0058] Each electrode may be formed by printing or the like in
which a conductive material is used, or by covering the substrate 2
with a conductive material and then forming a non-conductive track
by laser ablation or the like. For example, the conductor layer 3
can be formed by sputtering palladium onto the substrate 2, and
forming a non-conductive track by laser ablation. The
non-conductive track preferably has a width of 0.01 to 0.5 mm, and
more preferably 0.05 to 0.3 mm.
[0059] There are no particular restrictions on the material of the
conductor layer 3, so long as it is a conductive material
(conductive substance). Examples of conductive materials include
inorganic conductive substances, typified by metals, metal
mixtures, alloys, metal oxides, and metal compounds; organic
conductive substances, such as hydrocarbon-based conductive
polymers and hetero atom-containing conductive polymers; and
combinations of these. The material used for the conductor layer 3
is preferably palladium, gold, platinum, carbon, or the like.
[0060] The thickness of the conductor layer 3 can be varied
according to how the layer is formed and the material of which it
is made. For example, if the conductor layer 3 is formed by
sputtering, the thickness of the conductor layer 3 is preferably
0.1 to 20 nm, and more preferably 1 to 10 nm. If the conductor
layer 3 is formed by printing, the thickness of the conductor layer
3 is preferably 0.1 to 50 .mu.m, and more preferably 1 to 30
.mu.m.
[0061] (1-4) Reagent Layer
[0062] As shown in FIGS. 1 and 2, the reagent layer 4 is disposed
touching the electrodes 31 to 33.
[0063] The reagent layer 4 functions as the active component of the
sensor 1 along with the electrodes 31 and 32. The "active
component" is the region that is electrochemically active, and is
the portion that reacts with a specific substances in the
biological sample, producing an electrical signal. More
specifically, the reagent layer 4 includes an enzyme and an
electron acceptor.
[0064] The reagent layer 4 may be disposed so as to be in contact
with part of at least the electrodes 31 and 32 (the first electrode
and the second electrode). The reagent layer 4 may further be
disposed so as to be in contact with the electrode 33.
[0065] The reagent layer 4 has an electron acceptor and an
enzyme.
[0066] The amount of electron acceptor contained in the reagent
layer 4 can be set to an amount that is enough for the sensor to
function, and is preferably set to between 1 and 500 nmol, and more
preferably about 10 to 200 nmol, per measurement or per sensor
1.
[0067] The amount in which the enzyme is contained in the reagent
layer 4 is set to be enough to detect the target substance, and is
preferably set to between 0.2 and 20 U (units), and more preferably
about 0.5 to 10 U, per sensor 1 or per measurement.
[0068] A redox enzyme can be used favorably as the enzyme. A "redox
enzyme" encompasses oxidative enzymes and dehydrogenation enzymes.
Examples of redox enzymes include the following. Glucose oxidase
and glucose dehydrogenase are preferable as enzymes in which
glucose is the substrate; lactic acid oxidase and lactic acid
dehydrogenase are preferable as enzymes in which lactic acid is the
substrate; cholesterol esterase and cholesterol oxidase are
preferable as enzymes in which cholesterol is the substrate;
alcohol oxidase is preferable as an enzyme in which alcohol is the
substrate; and bilirubin oxidase is preferable as an enzyme in
which bilirubin is the substrate.
[0069] The reagent composition may include a co-enzyme that matches
the enzyme.
[0070] The role of the electron acceptor when the reagent layer 4
includes an enzyme that oxidizes the substrate will be described.
The enzyme oxidizes the substrate and thereby takes electrons from
the substrate and gives electrons to the co-enzyme. As a result,
the co-enzyme goes from an oxidant to a reductant.
[0071] An electron acceptor, which is an oxidant, takes electrons
from a co-enzyme that has become a reductant, and returns the
co-enzyme to being an oxidant. As a result, the electron acceptor
itself becomes a reductant. The electron acceptor that has become a
reductant gives electrons to the electrode 31 or 32, and itself
becomes an oxidant. In this way, the electron acceptor mediates
electron movement between the enzyme and the electrodes.
[0072] The above-mentioned co-enzyme may bond to an enzyme protein
(enzyme molecule) and thereby be supported on the enzyme protein.
The co-enzyme may also exist in a state of being separated from the
enzyme protein.
[0073] The reagent layer 4 can be formed by various methods.
Examples of formation methods include printing and coating.
[0074] The shape of the reagent layer 4 can be changed in many
ways, including rectangular and circular shapes. The surface area
of the reagent layer 4 (the surface area in the planar direction of
the substrate 2) is determined according to the characteristics and
size of the device. This surface area is preferably 1 to 25
mm.sup.2, and more preferably 2 to 10 mm.sup.2.
[0075] The amounts in which the enzyme, the electron acceptor, and
other components are contained in the aqueous solution that used
for coating are selected according to the required characteristics
and size of the device.
[0076] (1-5) Spacer 5 and Cavity 51
[0077] As shown in FIGS. 1 and 2, the spacer 5 is a member that
provides a space between the cover 6 and the conductor layer 3
formed on the substrate 2.
[0078] More specifically, the spacer 5 is a flat member that covers
the entire conductor layer 3 except for the lead portions of the
electrodes 31 to 33 and the cavity 51 portion. The spacer 5
comprises a cutout that exposes the end on the opposite side from
the lead portion of the electrodes 31 to 33. This cutout is
rectangular in FIGS. 1 and 3.
[0079] Because the spacer 5 has this cutout, the cavity 51 is
surrounded by the spacer 5, the conductor layer 3, and the cover 6.
Thus, the spacer 5 provides the side walls of the cavity 51, and
can also specify the length, width, height, etc., of the cavity
51.
[0080] The volume of the cavity 51 is set to about 0.05 to 5.0
.mu.L (microliters), and preferably about 0.1 to 1.0 .mu.L. The
thickness of the spacer 5 is about 0.02 to 0.5 mm, and preferably
about 0.1 to 0.2 mm. The length of the cutout in the spacer 5 is
preferably 1 to 5 mm. The width of the spacer 5 is about 0.25 to 4
mm, and preferably about 0.5 to 2 mm.
[0081] These dimensions should be suitably selected so that the
cavity 51 will have the desired volume. For instance, if the spacer
5 has a thickness of 0.145 mm and comprises a cutout with a length
of 3.4 mm and a width of 1.2 mm, the cavity 51 will have a length
of 3.4 mm, a width of 1.2 mm, a height of 0.145, and a volume of
approximately 0.6 .mu.L.
[0082] The cavity 51 has a shape that is longer in the lengthwise
direction of the sensor 1. The two ends in the lengthwise direction
of the sensor 1 are called the first end 53 and the second end 54.
A suction opening 52 is an opening provided at the first end 53,
and leads from the outside of the sensor 1 to the inside of the
cavity 51. The biological sample is drawn in by capillary action
from the suction opening 52, and held on the electrodes 31 to 33.
The shape of the cavity 51 will be discussed in detail below.
[0083] (1-6) Cover
[0084] As shown in FIGS. 1 and 2, the cover 6 is a flat member that
covers the entire spacer 5.
[0085] The cover 6 comprises a hole that goes through from the
front to the back. This hole functions as a vent opening 61 that
leads from the cavity 51 to the outside. The vent opening 61 is an
exhaust hole for letting air inside the cavity 51 escape from the
cavity when a biological sample is drawn into the cavity 51.
[0086] Thus discharging the air makes it easier for the biological
sample to be drawn into the cavity 51. The vent opening 61 is
preferably provided at a location away from the suction opening 52,
that is, deeper inside the cavity 51 as viewed from the suction
opening 52. When the suction opening 52 is disposed in this way,
the biological sample can quickly move from the suction opening 52
to the back of the cavity 51.
[0087] It is also preferable for the vent opening 61 to be disposed
more to the back than the reagent layer 4 that is placed on the
conductor layer of the sensor 1, and more to the front than the
second end 54.
[0088] 2. Shape of Cavity
[0089] The cavity 51 has a diverter. The diverter has a concave
portion or a convex portion provided to the inner wall of the
cavity 51.
[0090] The "inner wall" here encompasses a side wall provided
between the first end 53 and the second end 54; a back wall
provided at the end of the cavity 51, that is, to the second end
54; a bottom; and a ceiling that is opposite the bottom.
[0091] The side wall and back wall are formed in the thickness
shape of the spacer 5, the bottom is formed by the upper face of
the substrate 2, and the ceiling is formed by the lower face of the
cover 6. That is, either the cutout of the spacer 5 has a concave
portion or convex portion in the planar direction of the spacer 5,
or a concave portion or convex portion is provided to the upper
face of the substrate 2, or a concave portion or convex portion is
provided to the lower face of the cover 6.
[0092] A biological sample deposited in the suction opening 52 is
drawn into the cavity 51 by capillary action. The biological sample
advances particularly well at the corner portions of the interior
of the cavity 51, that is, at the portions where the spacer 5 and
the cover 6 are joined, and the portions where the spacer 5 and the
substrate 2 are joined.
[0093] When the biological sample works its way forward (wicking)
along the edges of the side walls toward the back, and reaches the
detecting electrode 33 disposed at the back of the cavity 51, there
is the risk of a false detection that a biological sample has been
introduced even though the amount of biological sample is
inadequate.
[0094] To deal with this, with the sensor in this embodiment, a
diverter is provided, which either prevents the biological sample
from moving forward, or increases how long it takes to reach the
detecting electrode 33. As a result, either false detection caused
by wicking is suppressed, or the time it takes for a false
detection to occur after the biological sample is deposited is
extended. More specifically, the time until a false detection
occurs should be about 30 seconds. This allows the user to deposit
additional biological sample.
[0095] The shape of the diverter may be linear or it may be a
curved shape, and is not limited to any specific shape.
[0096] The amount by which the concave portion and convex portion
are recessed and protrude from the inner wall of the cavity 51 at
the diverter may vary with the linear distance from the suction
opening 52 to the detecting electrode 33. The amounts of recess and
protrusion are preferably at least approximately 10% of the width
of the cavity 51, and more preferably at least 17%. That is, if the
cavity 51 is 1.2 mm wide, then the amounts of recess and protrusion
should be about 120 to 500 mm.
[0097] Examples of various cavity shapes that can be applied to the
sensor 1 will now be given. The electrodes other than the detecting
electrode 33 will not be depicted in the drawings for the following
description. Also, those members and portions having the same
function are numbered the same, and will not be described
again.
[0098] Also, in FIGS. 6 to 16, the shape of the side walls is in
right and left symmetry, but the present invention is not limited
to this, and the left and right side walls may have different
shapes.
[0099] (1) First Mode
[0100] As shown in FIG. 4, with the sensor in this embodiment, in
this mode a spacer 201 has a rectangular cutout. Left and right
side walls 401 both have a planar shape, and a back wall 55 also
has a planar shape.
[0101] In this case, a concave portion and/or a convex portion is
provided to the bottom or the ceiling, so that a cavity 300 has a
diverter.
[0102] (2) Second Mode
[0103] As shown in FIG. 5, with the sensor in this embodiment, in
this mode a cutout in a spacer 202 is formed so that the sides are
parallel near the suction opening 52 and spread out wider (toward
the back wall 55) near the back wall 55.
[0104] That is, a triangular concave portion 502 including the back
wall 55 as one of its sides is provided to left and right side
walls 402 of a cavity 302. In a specific range from the suction
opening 52 toward the back of the cavity 302, the left and right
side walls 402 of the cavity 302 are parallel, and the distance
between the left and right side walls 402 of the cavity 302
increases going toward the back.
[0105] With this configuration, the distance D1 along the side
walls 402 from the suction opening 52 to the back wall 55 is
greater than the linear distance D2 from the suction opening 52 to
the back wall 55 (from the first end 53 to the second end 54). It
is particularly favorable if the relation D1.gtoreq.1.05.times.D2
is satisfied.
[0106] The fact that it is preferable for D1 to be greater than D2
and for the relation D1.gtoreq.1.05.times.D2 to be satisfied also
applies to FIGS. 6 to 16. It is particularly favorable for the
relation D1.gtoreq.1.07.times.D2 to be satisfied, and satisfying
D1.gtoreq.1.65.times.D2 is even better.
[0107] (3) Third Mode
[0108] As shown in FIG. 6, in this embodiment, a spacer 203
comprises a triangular concave portion.
[0109] More specifically, a concave portion 503 is formed in left
and right symmetry so that side walls 403 of a cavity 303 comprise
a portion where the left and right side walls 402 of the cavity 302
are parallel from the suction opening 52 toward the back of the
cavity 302, a portion where these are recessed at a right angle,
and a portion where the distance between the left and right side
walls 402 of the cavity 302 decreases going toward the back.
[0110] As shown in FIG. 6, the angle A1 of the concave portion with
respect to the linear portion of the inner wall of the cavity is
preferably at least 270 degrees.
[0111] This enhances the anti-wicking effect. The same applies
regardless of the shape of the concave portion.
[0112] If the concave portion has an elliptical arc shape, then the
angle of a tangent of the elliptical arc at the position on the
concave portion closest to the linear portion of the inner wall of
the cavity, with respect to this linear portion, is preferably at
least 270 degrees.
[0113] As shown in FIG. 11, however, if there is a combination of a
concave portion and a convex portion, an anti-wicking effect can be
easily obtained even at a smaller angle than this.
[0114] (4) Fourth Mode
[0115] As shown in FIG. 7, with the sensor in this embodiment, a
spacer 204 comprises a rectangular concave portion.
[0116] More specifically, side walls 404 of a cavity 304 comprise a
concave portion 504 having an open box shape that includes the back
wall 55.
[0117] (5) Fifth Mode
[0118] As shown in FIG. 8, with the sensor in this embodiment, a
spacer 205 comprises a trapezoidal concave portion. More
specifically, a concave portion 505 is formed which comprises the
back wall 55 as a leg that is perpendicular to the bottom edge.
[0119] (6) Sixth Mode
[0120] As shown in FIG. 9, with the sensor in this embodiment, a
spacer 206 comprises a concave portion with an elliptical arc
shape. More specifically, a concave portion 506 that comprises an
elliptical arc continuous with the back wall 55 is formed in side
walls 406 of a cavity 306.
[0121] (7) Seventh Mode
[0122] As shown in FIG. 10, with the sensor in this embodiment, a
spacer 207 comprises a concave portion with a circular arc shape.
More specifically, a concave portion 507 that is bounded by the
planar back wall 55 and circular arc-shaped side walls 407 is
formed in side walls 407 of a cavity 307.
[0123] (8) Eighth Mode
[0124] As shown in FIG. 11, with the sensor in this embodiment, a
spacer 208 has a triangular convex portion. More specifically, a
rounded triangular convex portion 608 is formed in side walls 408
of a cavity 308 at a position near the back wall 55. It could be
said that forming the convex portion 608 forms a concave portion
508 between the convex portion 608 and the back wall 55.
[0125] Just as in this mode, all the other shapes of the cavity
inner walls described in this Specification actually can have
rounded corners, even though they are shown as linear corners in
the drawings.
[0126] (9) Ninth Mode
[0127] With the sensor in this embodiment, the shape of the convex
portion may be rectangular or fan shaped, and the position of the
convex portion may be away from the back wall 55.
[0128] As shown in FIG. 12, a spacer 209 has a rectangular convex
portion. That is, side walls 409 of a cavity 309 have a rectangular
convex portion 609. The convex portion 609 is disposed between the
suction opening 52 and the detecting electrode 33 at the back of
the cavity 309. It could be said that providing the convex portion
609 forms a concave portion between the convex portion 609 and the
back wall 55.
[0129] (10) Tenth Mode
[0130] As shown in FIG. 13, with the sensor in this embodiment, a
convex portion of a spacer 210 has a circular arc shape.
[0131] More specifically, side walls 410 of a cavity 310 have a
convex portion 610 having a circular arc shape instead of the
rectangular convex portion 609 in FIG. 12.
[0132] (11) Eleventh Mode
[0133] With the sensor in this embodiment, the fact that the inner
walls of the cavity have a concave portion and a convex portion
includes a case in which the inner walls of the cavity have a
stepped structure.
[0134] As shown in FIG. 14, a spacer 211 has a Z-shaped portion at
the cutout. As a result, side walls 411 of a cavity 311 comprise a
stepped structure having a concave portion 511 and a convex portion
611. The convex portion 611 protrudes toward the inside of the
cavity 311 and the suction opening 52, and the concave portion 511
is recessed toward the outside of the cavity 311 and the back wall
55.
[0135] (12) Twelfth Mode
[0136] With the sensor in this embodiment, the number of concave
portions and convex portions may be two or more.
[0137] As shown in FIG. 15, if the cutout in a spacer 212 has a
plurality of Z-shaped structures, a cavity 312 will comprise three
convex portions 612 and concave portions 512 on each of the left
and right side walls 412.
[0138] (13) Thirteenth Mode
[0139] With the sensor in this embodiment, the concave portion,
just like the convex portion 610 in FIG. 13, does not need to be
formed near the back wall 55.
[0140] For example, as shown in FIG. 16, a spacer 213 comprises a
concave portion 513 between the detecting electrode 33 and the
suction opening 52, at a place corresponding to side walls 413 of a
cavity 313.
[0141] (14) Fourteenth Mode
[0142] As shown in FIG. 17, with the sensor in this embodiment, a
substrate 20 of a sensor comprises a convex portion 614, and a
cover 63 comprises a convex portion 624.
[0143] The substrate 20 and the cover 63 are disposed so that the
convex portion 614 and the convex portion 624 are opposite each
other. Specifically, a cavity 314 has the convex portion 624 and
the convex portion 614 in vertical symmetry with a ceiling 64 and a
bottom 21. The convex portion 624 and the convex portion 614 do not
need to be disposed at positions of vertical symmetry, and these
positions can be changed.
[0144] Instead of a convex portion, or along with a convex portion,
a concave portion may be formed on the ceiling 64 and/or the bottom
21.
[0145] The spacer 214 may comprise the various convex portions or
concave portions discussed above, or may comprise a flat cutout.
Specifically, the ceiling and bottom on which the concave portions
and/or convex portion are formed can be combined with the side
walls on which the concave portions and/or convex portion are
formed.
[0146] (15) Fifteenth Mode
[0147] As shown in FIG. 18, with the sensor in this embodiment, the
diverter discussed above can also be applied to the cavity of a
side-fill type of sensor.
[0148] With the side-fill sensor shown in FIG. 18, the lengthwise
direction of a cavity 315 is parallel to the short-side direction
of the sensor, and the suction opening 52 is provided at the end in
the short-side direction of the sensor.
[0149] The detecting electrode 33 is disposed at the back of the
cavity 315 as viewed from the suction opening 52. Forming a concave
portion in the spacer 215 provides concave portions in left and
right symmetry to the side walls at the back of the cavity 315.
[0150] (16) Sixteenth Mode
[0151] As shown in FIG. 19, with the sensor in this embodiment, a
side-fill sensor may comprise two suction openings 52.
Specifically, a cavity 316 comprises suction openings 52 at both of
its ends. A working electrode 31 and a counter electrode 32 are
provided in the center of the cavity 316. The detecting electrode
33 is provided near each of the two suction openings 52. No matter
in which of the suction openings 52 the sample is deposited,
suction of the sample will be detected when the sample reaches the
suction opening 52 on the opposite side.
[0152] In FIG. 19, a spacer 216 comprises a concave portion, so
that the side walls of the cavity 316 have two rectangular concave
portions 516 provided in left and right symmetry near the center in
the lengthwise direction.
[0153] (17) Other
[0154] As can be seen from the above description, a configuration
in which the inner walls of the cavity have a convex portion can
also be called a configuration having a concave portion. The same
applies to the reverse, and a configuration having a concave
portion can be called a configuration having a convex portion.
However, it will be understood that a concave portion will be
formed if the distance between opposing inner walls is greater than
the width of the cavity interior at the suction opening 52, and a
convex portion will be formed if this distance is less than this
width.
[0155] Wicking tends to occur in the corners of the cavity (such
the corners between the side walls and ceiling, and between the
side walls and the bottom), so the concave portions and convex
portions are preferably provided so as to reach the corners of the
cavity. However, concave portions or convex portions provided to a
flat portion inside the cavity can suppress false detection such as
when the biological sample seeps through to the reagent layer
4.
[0156] The concave portions and convex portions that serve as the
diverter can be formed by milling the spacer with a laser, for
example. The diverter can also be formed, for example, by dropping
a resin onto the cover or substrate and curing, or by etching or
some other method.
[0157] 3. Sensor System
[0158] The above-mentioned sensor 1 is used in the sensor system
100 shown in FIG. 20. The sensor system 100 has the sensor 1 and
the measurement device 101.
[0159] As shown in FIGS. 20 and 21, the measurement device 101
comprises a display section 102, a mounting portion 103, a
switching circuit 107, a reference voltage source 108, a
current/voltage conversion circuit 109, an A/D conversion circuit
110, a computer 111, an interface section 113, and a power supply
112. The measurement device 101 further has connectors
corresponding to the various electrodes of the sensor 1. In FIG.
21, the connectors 104 to 106 are shown as being provided inside
the mounting portion 103.
[0160] The display section 102 displays the status of the
measurement device 101, measurement results, user input details,
and so forth. More specifically, the display section 102 comprises
a liquid crystal display panel.
[0161] As shown in FIG. 20, the sensor 1 can be removably inserted
into the mounting portion 103.
[0162] As shown in FIG. 21, the connectors 104 to 106 are connected
to the electrodes 31 to 33, respectively, of the sensor 1 when the
sensor 1 is mounted to the mounting portion 103.
[0163] The switching circuit 107 can connect the connectors 104 to
106 to the reference voltage source 108, and can also connect them
to the current/voltage conversion circuit 109.
[0164] The reference voltage source 108 applies voltage through the
connectors 104 to 106 to the electrodes 31 to 33.
[0165] The current/voltage conversion circuit 109 takes current
from the sensor 1 through the connectors 104 to 106, converts it
into voltage, and outputs it to the A/D conversion circuit 110.
[0166] The A/D conversion circuit 110 converts a voltage value
(analog value) that is the output from the current/voltage
conversion circuit 109 into a digital value.
[0167] The computer 111 has a CPU (Central Processing Unit) and a
recording medium, such as a ROM (Read Only Memory) or a RAM (Random
Access Memory). The computer 111 computes the concentration of a
target substance, and controls the operation of the various
components inside the measurement device 101.
[0168] The concentration computation function of the computer 111
will be described. The recording medium of the computer 111 stores
conversion tables used in determining the concentration of a target
substance in a sample, correction amount tables used in determining
the amount by which this concentration is to be corrected, and so
forth. The computer 111 calculates a temporary concentration of the
target substance by referring to a conversion table on the basis of
a pulse from the A/D conversion circuit 110. The computer 111 then
uses a correction amount in the correction amount table to
determine the final concentration of the target substance. The
concentration thus calculated is displayed on the display section
102.
[0169] Other functions of the computer 111 besides the
concentration calculation function include controlling switching of
the switching circuit 107, controlling the voltage of the reference
voltage source 108, measuring concentration, measuring the time
during correction amount selection (timer function), outputting
display data to the display section 102, and communicating with
external devices.
[0170] The various functions of the computer 111 are performed when
the CPU reads and executes a program stored in a ROM or the like
(not shown).
[0171] The interface section 113 is provided to the surface of the
measurement device 101. The interface section 113 comprises buttons
or the like that are operated by the user to refer to measurement
data or setting data, for example.
[0172] The power supply 112 comprises a battery or the like that
supplies power to the above-mentioned various electrical circuits,
display section, computer, and so on.
[0173] 4. Use of Sensor System
[0174] The measurement of concentration by the sensor system 100
will now be described.
[0175] When the sensor 1 is plugged into the mounting portion 103,
the connectors 104 to 106 are connected to the electrodes 31 to 33,
respectively. Also, mounting the sensor 1 to the mounting portion
103 pushes down a switch (not shown) in the mounting portion 103.
This switch goes ON when pushed down, and the computer 111
determines that the sensor 1 has been mounted, putting the
measurement device 101 in a sample standby state. A "sample standby
state" is a state in which no biological sample has yet been
supplied for measurement, after the application of voltage between
the working electrode 31 and the detecting electrode 33 has begun,
and the measurement of current by the current/voltage conversion
circuit 109 has begun.
[0176] When the user deposits a biological sample in the suction
opening 52 of the sensor 1, the sample is drawn by capillary action
from the suction opening 52 into the cavity 51.
[0177] Examples of samples that can be used include blood,
perspiration, urine and other biological samples that come from the
body. For instance, when the sensor 1 is used as a blood glucose
level sensor, the user prick his own ringer, palm, arm, or the
like, squeezes out a small amount of blood, and supplies this blood
as a biological sample for measurement by the sensor 1.
[0178] When the biological sample reaches the working electrode 31
and the detecting electrode 33, there is a change in the current
value taken by the computer 111 through the current/voltage
conversion circuit 109. The computer 111 determines from this
change that a biological sample has been properly drawn into the
sensor 1. Measurement begins once the intake of a biological sample
has thus been detected.
[0179] If no sample can be detected at the detecting electrode 33,
the computer 111 performs control so that an error message
prompting the deposit of more biological sample is displayed on the
display section 102. As discussed above, because the cavity of the
sensor 1 has a diverter, the user has enough time to add more
biological sample (about 30 seconds) more a false detection occurs
at the detecting electrode 33.
[0180] Inside the sensor 1, the enzymes, electron acceptors, and
other such components in the reagent layer 4 dissolve into the
biological sample. This causes the biological sample, the enzymes,
and the electron acceptors to come into contact with each other on
the electrodes 31 and 32 of the sensor 1.
[0181] The computer 111 performs control so that the switching
circuit 107 connects the connector 104 and the connector 105 to the
reference voltage source 108 and the current/voltage conversion
circuit 109. This applies voltage between the working electrode 31
and the counter electrode 32, and the current produced between the
working electrode 31 and the counter electrode 32 is transmitted to
the current/voltage conversion circuit 109.
[0182] The current that flows to the current/voltage conversion
circuit 109 is converted into voltage. This voltage is further
converted into a digital value by the A/D conversion circuit 110.
The computer 111 calculates the concentration of a particular
component from this digital value. The value calculated by the
computer 111 is displayed on the display section 102. Other
information can also be displayed and thus conveyed to the user at
this point.
[0183] Once the measurement is complete, the user can take the
sensor 1 out of the mounting portion 103.
[0184] The reference voltage source 108 imparts enough voltage
between the two electrodes 31 and 32 to bring about the targeted
electrochemical reaction. This voltage is mainly set according to
the chemical reaction and electrodes being used.
INDUSTRIAL APPLICABILITY
[0185] The present invention can be widely applied to sensors used
in the detection and/or quantification of a target substance in a
biological sample, such as blood glucose sensors.
GENERAL INTERPRETATION OF TERMS
[0186] In understanding the scope of the present disclosure, the
term "comprising" and its derivatives, as used herein, are intended
to be open ended terms that specify the presence of the stated
features, elements, components, groups, integers, and/or steps, but
do not exclude the presence of other unstated features, elements,
components, groups, integers and/or steps. The foregoing also
applies to words having similar meanings such as the terms,
"including", "having" and their derivatives. Also, the terms
"part," "section," "portion," "member" or "element" when used in
the singular can have the dual meaning of a single part or a
plurality of parts. Also as used herein to describe the above
embodiment(s), the following directional terms "forward",
"rearward", "above", "downward", "vertical", "horizontal", "below"
and "transverse" as well as any other similar directional terms
refer to those directions of the sensor and sensor system equipped
with the same. Accordingly, these terms, as utilized to describe
the technology disclosed herein should be interpreted relative to
sensor and sensor system equipped with the same.
[0187] The term "configured" as used herein to describe a
component, section, or part of a device includes hardware and/or
software that is constructed and/or programmed to carry out the
desired function.
[0188] The terms of degree such as "substantially", "about" and
"approximately" as used herein mean a reasonable amount of
deviation of the modified term such that the end result is not
significantly changed.
[0189] While only selected embodiments have been chosen to
illustrate the present invention, it will be apparent to those
skilled in the art from this disclosure that various changes and
modifications can be made herein without departing from the scope
of the invention as defined in the appended claims. For example,
the size, shape, location or orientation of the various components
can be changed as needed and/or desired. Components that are shown
directly connected or contacting each other can have intermediate
structures disposed between them. The functions of one element can
be performed by two, and vice versa. The structures and functions
of one embodiment can be adopted in another embodiment. It is not
necessary for all advantages to be present in a particular
embodiment at the same time. Every feature which is unique from the
prior art, alone or in combination with other features, also should
be considered a separate description of further inventions by the
applicants, including the structural and/or functional concepts
embodied by such feature(s). Thus, the foregoing descriptions of
the embodiments according to the present invention are provided for
illustration only, and not for the purpose of limiting the
invention as defined by the appended claims and their
equivalents
* * * * *