U.S. patent application number 10/976740 was filed with the patent office on 2008-12-25 for method of making a biosensor.
Invention is credited to John T. Austera, Raghbir S. Bhullar, Henning Groll, James L. Pauley, JR., Timothy L. Ranney, Douglas P. Walling.
Application Number | 20080314882 10/976740 |
Document ID | / |
Family ID | 25478187 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080314882 |
Kind Code |
A1 |
Bhullar; Raghbir S. ; et
al. |
December 25, 2008 |
METHOD OF MAKING A BIOSENSOR
Abstract
The present invention relates to a method of forming a
biosensor. The method includes providing a substrate coated with a
electrically conductive material, ablating the electrically
conductive material to form electrodes and a code pattern, wherein
there is sufficient contrast between the conductive coating and the
substrate such that the code pattern is discernible, and applying a
reagent to at least one of the electrodes.
Inventors: |
Bhullar; Raghbir S.;
(Indianapolis, IN) ; Groll; Henning;
(Indianapolis, IN) ; Austera; John T.;
(Indianapolis, IN) ; Walling; Douglas P.;
(Indianapolis, IN) ; Ranney; Timothy L.; (Lebanon,
IN) ; Pauley, JR.; James L.; (Fishers, IN) |
Correspondence
Address: |
The Law Office of Jill L. Woodburn, LLC
128 Shore Dr.
Portage
IN
46368
US
|
Family ID: |
25478187 |
Appl. No.: |
10/976740 |
Filed: |
October 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09942515 |
Aug 29, 2001 |
6814844 |
|
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10976740 |
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Current U.S.
Class: |
219/121.69 ;
435/287.2 |
Current CPC
Class: |
G01N 33/5438 20130101;
G01N 27/3272 20130101; G01N 2035/00811 20130101; G01N 33/48771
20130101 |
Class at
Publication: |
219/121.69 ;
435/287.2 |
International
Class: |
C12M 3/00 20060101
C12M003/00 |
Claims
1. A method of forming a biosensor, the method comprising the steps
of: providing a flexible substrate coated with an electrically
conductive material, ablating through the electrically conductive
material to expose the substrate in a pre-defined pattern so as to
form a pattern of electrodes and a code pattern electrically
isolated from the electrodes, wherein there is sufficient contrast
between the conductive material and the exposed substrate such that
the code pattern is discernible, and applying a reagent to at least
one of the electrodes.
2. The method of claim 1 wherein the ablating step includes the
step of laser ablating the electrically conductive material.
3. The method of claim 1 wherein the ablating step includes forming
a bar code shaped code pattern.
4. The method of claim 1 wherein the ablating step includes forming
a code pattern that includes pads isolated from the surrounding
electrically conductive material.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a biosensor, more
particularly to an electrochemical biosensor with a code pattern
thereon.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] Electrochemical biosensors are known. They have been used to
determine the concentration of various analytes from biological
samples, particularly from blood. Electrochemical biosensors are
described in U.S. Pat. Nos. 5,413,690; 5,762,770; 5,798,031; and
5,997,817 the disclosure of each of which is expressly incorporated
herein by reference. It is also known to include a code on a test
strip that identifies the manufacturing batch of the strip. See WO
99/22236.
[0003] According to one aspect of the present invention a biosensor
is provided. The biosensor comprises a support substrate, an
electrically conductive coating positioned on the support
substrate, the coating being formed to define electrodes and a code
pattern, wherein there is sufficient contrast between the
conductive coating and the substrate such that the code pattern is
discernible, and at least one reagent positioned on at least one
electrode.
[0004] According to another aspect of the present invention a
biosensor is provided. The biosensor comprises a support substrate,
an electrically conductive coating positioned on the support
substrate, the coating being formed to define electrodes and a code
pattern, wherein there is sufficient contrast between the
conductive coating and the substrate such that the code pattern is
discernible, and a cover cooperating with the support substrate to
define a channel. At least a portion of the electrodes are
positioned in the channel.
[0005] In addition, a method of forming a biosensor is provided in
accordance with the present invention. The method comprises the
steps of providing a substrate coated with a electrically
conductive material, ablating the electrically conductive material
to form electrodes and a code pattern, wherein there is sufficient
contrast between the conductive coating and the substrate such that
the code pattern is discernible, and applying a reagent to at least
one of the electrodes.
[0006] Still further, in accordance with the present invention a
biosensor is provided. The biosensor comprises a support substrate
and an electrically conductive coating positioned on the support
substrate. The coating is formed to define electrodes and means for
identifying the biosensor, wherein there is sufficient contrast
between the conductive coating and the substrate such that the
identifying means is discernible.
[0007] Additional features of the invention will become apparent to
those skilled in the art upon consideration of the following
detailed description of the preferred embodiment exemplifying the
best mode of carrying out the invention as presently perceived.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The detailed description particularly refers to the
accompanying figures in which:
[0009] FIG. 1 is a perspective view of a biosensor in accordance
with the present invention, showing the biosensor formed to include
a code pattern formed thereon.
[0010] FIG. 2 is an exploded assembly view of the biosensor of FIG.
1, showing the biosensor including an electrode array positioned at
one end, a spacer substrate including a notch, and a cover formed
to extend over a portion of the notch.
[0011] FIG. 3 is a view taken along lines 3-3 of FIG. 1.
[0012] FIG. 4 is a view taken along lines 4-4 of FIG. 1.
[0013] FIG. 5 is an enlarged top view of an alternative code
pattern formed on a biosensor in accordance with the present
invention.
[0014] FIG. 6 is an enlarged top view of an alternative code
pattern formed on a biosensor in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The present invention relates to a biosensor and a method
for manufacturing a biosensor that has a specific code pattern.
This code pattern is beneficially formed from the same electrically
conductive material and in the same manner as the electrodes of the
biosensor, which reduces steps in the manufacturing process. Laser
ablation is preferably used in forming the code pattern while
generating the electrode pattern. The code pattern can be read in a
number of ways, non-limiting examples of which include optically or
electrically depending on the structures formed onto the biosensor.
The structures could show contrast in their optical reflectivity,
their electrical conductivity, or their resistance respectively.
The structures could also be high reflectivity areas surrounded by
low reflectivity areas or vice versa, or areas of high electrical
conductivity surrounded by areas of low conductivity. Aspects of
the invention are presented in FIGS. 1-6, which are not drawn to
scale and wherein like components in the several views are numbered
alike.
[0016] FIGS. 1-4 illustrate an aspect of the invention in the form
of a biosensor 10 having an electrode-support substrate 12, an
electrical conductor 13 positioned on the substrate 12 that is
disrupted to define electrodes 14, 16, a spacer substrate 18
positioned on substrate 12, and a cover substrate 20 positioned on
the spacer substrate 18. Biosensor 10 is preferably rectangular in
shape. It is appreciated however, that biosensor 10 can assume any
number of shapes in accordance with this disclosure. Biosensor 10
is preferably produced from rolls of material however, it is
understood that biosensor 10 can be constructed from individual
sheets in accordance with this disclosure. Thus, the selection of
materials for the construction of biosensor 10 necessitates the use
of materials that are sufficiently flexible for roll processing,
but which are still rigid enough to give a useful stiffness to
finished biosensor 10.
[0017] Referring to FIG. 4, the support substrate 12 includes a
first surface 22 facing the spacer substrate 18 and a second
surface 24. In addition, as shown in FIG. 2, substrate 12 has
opposite first and second ends 26, 28 and opposite edges 30, 32
extending between the first and second ends 26, 28. Substrate 12 is
generally rectangular in shape, it is appreciated however, that
support may be formed in a variety of shapes and sizes in
accordance with this disclosure. Substrate 12 is formed of a
flexible polymer and preferably from a flexible polymer and
preferably from a polymer such as a polyester or polyimide,
polyethylene naphthalate (PEN). A non-limiting example of a
suitable PEN is 5 mil (125 um) thick KALADEX.RTM., a PEN film
commercially available from E.I. DuPont de Nemours, Wilmington,
Del., which is coated with gold by ROWO Coating, Henbolzhelm,
Germany.
[0018] Electrodes 14, 16 are created or isolated from conductor 13
on first surface 22 of substrate 12. Non-limiting examples of a
suitable electrical conductor 13 include aluminum, carbon (such as
graphite), cobalt, copper, gallium, gold, indium, iridium, iron,
lead, magnesium, mercury (as an amalgam), nickel, niobium, osmium,
palladium, platinum, rhenium, rhodium, selenium, silicon (such as
highly doped polycrystalline silicon), silver, tantalum, tin,
titanium, tungsten, uranium, vanadium, zinc, zirconium, mixtures
thereof, and alloys, oxides, or metallic compounds of these
elements. Preferably, electrical conductor 13 is selected from the
following materials: gold, platinum, palladium, iridium, or alloys
of these metals, since such noble metals and their alloys are
unreactive in biological systems. Most preferably, electrical
conductor 13 is gold.
[0019] Electrodes 14, 16 are isolated from the rest of the
electrical conductor 13 by laser ablation. See FIG. 4. Techniques
for forming electrodes on a surface using laser ablation are known.
See, for example, U.S. patent application Ser. No. 09/411,940,
filed Oct. 4, 1999, and entitled "LASER DEFINED FEATURES FOR
PATTERNED LAMINATES AND ELECTRODE", the disclosure of which is
expressly incorporated herein by reference. Preferably, electrodes
14, 16 are created by removing the electrical conductor 13 from an
area extending around the electrodes to form a gap of exposed
support substrate 12. Therefore, electrodes 14, 16 are isolated
from the rest of the electrically-conductive material on substrate
12 by a gap having a width of about 25 .mu.m to about 500 .mu.m,
preferably the gap has a width of about 100 .mu.m to about 200
.mu.m. Alternatively, it is appreciated that electrodes 14, 16 may
be created by laser ablation alone on substrate 12. It is
appreciated that while laser ablation is the preferred method for
forming electrodes 14, 16 given its precision and sensitivity,
other techniques such as lamination, screen-printing, or
photolithography may be used in accordance with this
disclosure.
[0020] As shown in FIG. 2, electrodes 14, 16 cooperate with one
another to define an electrode array 36. In addition, electrodes
14, 16 each include a contact 34 and a lead 38 extending between
the contact 34 and the array 36. It is appreciated that the leads
38 extending from the array can be formed to have many lengths and
extend to a variety of locations on the electrode-support substrate
12. It is appreciated that the configuration of the electrode
array, the number of electrodes, as well as the spacing between the
electrodes may vary in accordance with this disclosure and that a
greater than one array may be formed as will be appreciated by one
of skill in the art.
[0021] Referring again to FIGS. 2 and 3, a recess 35 is formed from
the electrical conductor 13 by laser ablation using techniques as
described above. Recess is created by removing the electrical
conductor 13 to expose the first surface 22 of the support
substrate 12 adjacent to the first end 26. It is appreciated that a
portion of the first surface 22 may also be removed to form the
recess 35 in accordance with this disclosure.
[0022] In addition, as shown in FIGS. 1, 2, and 4, the discernible
code pattern 40 is formed from the electrical conductor 13 by laser
ablation using techniques as described above with reference to
electrodes 14, 16. Specifically, the code pattern 40 is created by
removing the electrical conductor 13 in a pre-defined pattern to
expose the first surface 22 of the support substrate 12. While
pattern 40 is illustratively a barcode type pattern, it is
appreciated that the pattern 40 can take on any number of shapes
and patterns, non-limiting examples of which are shown in FIGS. 5
and 6.
[0023] It is also appreciated that the pattern 40 can be provided
in a human readable, optical readable, or electrical readable form
in accordance with this disclosure. The structures could show
contrast in their optical reflectivity, their electrical
conductivity, or their resistivity respectively. To aid in
contrasting the electrical conductivity of the code pattern 40, the
electrical conductor 13 of the pattern 40 may be coated with a
second conductive material (not shown) that is different from the
electrical conductor 13. Non-limiting examples of the second
conductive material include carbon and silver. It is appreciated,
however, that a wide variety of materials may be coated on the
electrical conductor 13 to change the electrical property of the
code pattern 40.
[0024] It is also appreciated; electrodes 14, 16 could be formed
from layers of electrically conductive materials having different
colors, reflectivity, conductance, etc. Thus, the code pattern can
be formed by removing a portion of the electrical conductor layers,
leaving behind areas of high reflectivity surrounded by low
reflectivity areas or vice versa, areas of high electrical
conductivity surrounded by areas of low conductivity or vise versa.
It is also possible to laser etch a code pattern that has a known
resistance and this area can be read electrochemically to identify
or recognize the code pattern. Moreover, it is appreciated that the
code pattern can be a combination of any of the above readable
forms in accordance with the present invention.
[0025] As shown in FIG. 4, the code pattern 40 is isolated from the
rest of the electrically conductive material 13 on substrate 12 by
gaps 42. Gaps 42 can have a wide variety of widths in accordance
with this disclosure depending upon the specific use of the code
pattern 40. Non-limiting examples of widths of the gaps include
from about 1 .mu.m to about 1000 .mu.m. Alternatively, it is
appreciated that the code pattern 40 may be created by laser
ablation alone on substrate 12. It is appreciated that while laser
ablation is the preferred method for forming the code pattern 40
given its precision and sensitivity, other techniques such as
lamination, screen-printing, or photolithography may be used in
accordance with this disclosure.
[0026] The manufacturer of biosensor 10 may maintain a central
database containing a set of code patterns, each of which uniquely
identifies an individual biosensor, or batch of biosensors. There
may also be associated with each code pattern a set of calibration
data for the biosensor 10. It is appreciated that the code patterns
may be associated with any number of identification or data sets in
accordance with the present invention.
[0027] Spacer substrate 18 of biosensor 10 includes an upper
surface 44 and a lower surface 46 facing the substrate 12. In
addition, the spacer substrate 18 includes opposite first and
second ends 48, 50. First end 48 includes a notch 52, which is
defined by a border 54. The border illustratively includes three
generally linear sides. It is appreciated that the notch can take
on a variety of shapes and sizes in accordance with this
disclosure. When biosensor 10 is assembled, the border 54 extends
about at least a portion of the array 36 so that the array 36 is at
least partially exposed in the notch 52.
[0028] Spacer substrate 18 is formed of a flexible polymer and
preferably from a flexible polymer and preferably from a polymer
such as an adhesive coated polyethylene terephthalate (PET)
polyester. A non-limiting example of a suitable PET is 3 mil (75
um) thick white PET film both sides of which are coated with a
pressure-sensitive adhesive (Product # ARcare 8877) commercially
available from Adhesives Research, Inc. Glen Rock, Pa. It is
appreciated that spacer substrate 18 may be constructed of a
variety of materials and may be coupled to the substrate 12 and the
cover substrate 20 using a wide variety of commercially available
adhesives, or by welding (heat or ultrasonic) when large portions
of the surface 22 of the electrode support substrate 12 are exposed
and not covered by electrical conductor 13.
[0029] The cover substrate 20 is coupled to the upper surface 44 of
the spacer substrate 18. See FIG. 3. The cover substrate 20
includes opposite first and second ends 56, 58. The cover substrate
20 is coupled to the spacer substrate 18 such that the first end 56
is spaced-apart from the end 48 of the spacer substrate 18 and the
second end 58 is spaced-apart from the end 50 of the spacer
substrate 18. When biosensor 10 is assembled, cover substrate 20
cooperates with the spacer support 20 and the electrode-support 12
to define a capillary channel 60.
[0030] Cover substrate 20 is generally rectangular in shape, it is
appreciated, however, that the cover substrate may be formed in a
variety of shapes and sizes in accordance with this disclosure.
Cover substrate 20 is formed from a flexible polymer and preferably
from a polymer such as polyester. A non-limiting example of a
suitable polymer is 3.9 mil (99 um) thick 3M hydrophilic polyester
film (3M Product #9971), commercially available from 3M Healthcare,
St. Paul, Minn.
[0031] Referring now to FIGS. 1 and 3, the capillary channel 60 is
generally linear in shape and is defined by the cover substrate 20,
the electrode support substrate 12, and the border 54 of the spacer
substrate 18. When biosensor 10 is assembled, channel 60 extends
across the electrode array 36. Cover substrate 20 does not extend
across the entire notch 52, therefore, a portion of the notch
serves as an air outlet in accordance with this disclosure.
[0032] An electrochemical reagent 62 is positioned on the array 36.
The reagent 62 provides electrochemical probes for specific
analytes. The term analyte, as used herein, refers to the molecule
or compound to be quantitatively determined. Non-limiting examples
of analytes include carbohydrates, proteins, such as hormones and
other secreted proteins, enzymes, and cell surface proteins;
glycoproteins; peptides; small molecules; polysaccharides;
antibodies (including monoclonal or polyclonal Ab); nucleic acids;
drugs; toxins; viruses of virus particles; portions of a cell wall;
and other compounds processing epitopes. The analyte of interest is
preferably glucose.
[0033] The choice of the specific reagent 62 depends on the
specific analyte or analytes to be measured, and are well known to
those of ordinary skill in the art. An example of a reagent that
may be used in biosensor 10 of the present invention is a reagent
for measuring glucose from a whole blood sample. A non-limiting
example of a reagent for measurement of glucose in a human blood
sample contains 62.2 mg polyethylene oxide (mean molecular weight
of 100-900 kilo Daltons), 3.3 mg NATROSOL 244M, 41.5 mg AVICEL
RC-591 F, 89.4 mg monobasic potassium phosphate, 157.9 mg dibasic
potassium phosphate, 437.3 mg potassium ferricyanide, 46.0 mg
sodium succinate, 148.0 mg trehalose, 2.6 mg TRITON X-100
surfactant, and 2,000 to 9,000 units of enzyme activity per gram of
reagent. The enzyme is prepared as an enzyme solution from 12.5 mg
coenzyme PQQ and 1.21 million units of the apoenzyme of
quinoprotein glucose dehydrogenase. This reagent is further
described in U.S. Pat. No. 5,997,817, the disclosure of which is
expressly incorporated herein by reference.
[0034] Non-limiting examples of enzymes and mediators that may be
used in measuring particular analytes in biosensor 10 are listed
below in Table 1.
TABLE-US-00001 TABLE 1 Mediator Analyte Enzymes (Oxidized Form)
Additional Mediator Glucose Glucose Dehydrogenase Ferricyanide and
Diaphorase Glucose Glucose-Dehydrogenase Ferricyanide
(Quinoprotein) Cholesterol Cholesterol Esterase and Ferricyanide
2,6-Dimethyl-1,4- Cholesterol Oxidase Benzoquinone
2,5-Dichloro-1,4- Benzoquinone or Phenazine Ethosulfate HDL
Cholesterol Esterase Ferricyanide 2,6-Dimethyl-1,4- Cholesterol and
Cholesterol Oxidase Benzoquinone 2,5-Dichloro-1,4- Benzoquinone or
Phenazine Ethosulfate Triglycerides Lipoprotein Lipase,
Ferricyanide or Phenazine Methosulfate Glycerol Kinase, and
Phenazine Glycerol-3-Phosphate Ethosulfate Oxidase Lactate Lactate
Oxidase Ferricyanide 2,6-Dichloro-1,4- Benzoquinone Lactate Lactate
Dehydrogenase Ferricyanide and Diaphorase Phenazine Ethosulfate, or
Phenazine Methosulfate Lactate Diaphorase Ferricyanide Phenazine
Ethosulfate, or Dehydrogenase Phenazine Methosulfate Pyruvate
Pyruvate Oxidase Ferricyanide Alcohol Alcohol Oxidase
Phenylenediamine Bilirubin Bilirubin Oxidase 1-Methoxy- Phenazine
Methosulfate Uric Acid Uricase Ferricyanide
[0035] In some of the examples shown in Table 1, at least one
additional enzyme is used as a reaction catalyst. Also, some of the
examples shown in Table 1 may utilize an additional mediator, which
facilitates electron transfer to the oxidized form of the mediator.
The additional mediator may be provided to the reagent in lesser
amount than the oxidized form of the mediator. While the above
assays are described, it is contemplated that current, charge,
impedance, conductance, potential, or other electrochemically
indicated property of the sample might be accurately correlated to
the concentration of the analyte in the sample with biosensor 10 in
accordance with this disclosure.
[0036] A plurality of biosensors 10 are typically packaged in a
vial, usually with a stopper formed to seal the vial. It is
appreciated, however, that biosensors 10 may be packaged
individually, or biosensors can be folded upon one another, rolled
in a coil, stacked in a cassette magazine, or packed in blister
packaging.
[0037] Biosensor 10 is used in conjunction with the following:
[0038] 1. a power source in electrical connection with contacts 34
and capable of supplying an electrical potential difference between
electrodes 14, 16 sufficient to cause diffusion limited
electro-oxidation of the reduced form of the mediator at the
surface of the working electrode; and
[0039] 2. a meter in electrical connection with contacts 34 and
capable of measuring the diffusion limited current produced by
oxidation of the reduced form of the mediator with the above-stated
electrical potential difference is applied.
[0040] The meter is provided with a pattern reader that is capable
of reading the code pattern 40 into a memory of the meter. The
reader can be an electrical or optical reader in accordance with
the present invention. The reader is formed to read the code
pattern 40 when the biosensor 10 is inserted into the meter. When,
however, the code pattern is in a human readable form, it is
appreciated that the meter may include an interface, which permits
the user to input the information from the code pattern manually.
There are many ways to optically read code pattern 40 such as laser
scanners, pen-like wands, and charge-couple-device (CCD) scanners.
A non-limiting example of a suitable optical reader suitable for
use with the present invention includes a light emitting diode(s)
(LED), a lens, and a photodiode. It is appreciated that the reader
may be an independent internal component of the meter.
[0041] The meter may further be formed to transfer the code pattern
from the meter to a memory unit where it is stored. It is
appreciated that the memory unit can be formed to store information
regarding the specifics of the code pattern as well as patient
information including previous meter readings. The meter will
normally be adapted to apply an algorithm to the current
measurement, whereby an analyte concentration is provided and
visually displayed. Improvements in such power source, meter, and
biosensor system are the subject of commonly assigned U.S. Pat. No.
4,963,814, issued Oct. 16, 1990; U.S. Pat. No. 4,999,632, issued
Mar. 12, 1991; U.S. Pat. No. 4,999,582, issued Mar. 12, 1991; U.S.
Pat. No. 5,243,516, issued Sep. 7, 1993; U.S. Pat. No. 5,352,351,
issued Oct. 4, 1994; U.S. Pat. No. 5,366,609, issued Nov. 22, 1994;
White et al., U.S. Pat. No. 5,405,511, issued Apr. 11, 1995; and
White et al., U.S. Pat. No. 5,438,271, issued Aug. 1, 1995, the
disclosures of each of which are expressly hereby incorporated by
reference.
[0042] Many fluid samples may be analyzed. For example, human body
fluids such as whole blood, plasma, sera, lymph, bile, urine,
semen, cerebrospinal fluid, spinal fluid, lacrimal fluid and stool
specimens as well as other biological fluids readily apparent to
one skilled in the art may be measured. Fluid preparations of
tissues can also be assayed, along with foods, fermentation
products and environmental substances, which potentially contain
environmental contaminants. Preferably, whole blood is assayed with
this invention.
[0043] To manufacture biosensor 10 a roll of metallized electrode
support material is fed through guide rolls into an
ablation/washing and drying station. A laser system capable of
ablating support 12 is known to those of ordinary skill in the art.
Non-limiting examples of which include excimer lasers, with the
pattern of ablation controlled by mirrors, lenses, and masks. A
non-limiting example of such a custom fit system is the LPX-300 or
LPX-200 both commercially available from LPKF Laser Electronic
GmbH, of Garbsen, Germany.
[0044] In the laser ablation station, the metallic layer of the
metallized film is ablated in a pre-determined pattern, to form a
ribbon of isolated electrode sets on the electrode support
material, code patterns, and a recess in the film adjacent to each
electrode array. To ablate electrodes 14, 16, recess 35, and code
patterns 40 in 50 nm thick gold conductor 13, 90 mJ/cm.sup.2 energy
is applied. It is appreciated, however, that the amount of energy
required may vary from material to material, metal to metal, or
thickness to thickness. The ribbon is then passed through more
guide rolls, with a tension loop and through an optional inspection
system where both optical and electrical inspection can be made.
The system is used for quality control in order to check for
defects.
[0045] Upon leaving the laser ablation station, the metallized film
is fed into a reagent dispensing station. Reagents that have been
compounded are fed into a dispensing station where it is applied in
a liquid form to the center of respective the array 34. Reagent
application techniques are well known to one of ordinary skill in
the art as described in U.S. Pat. No. 5,762,770, the disclosure of
which is expressly incorporated herein by reference. It is
appreciated that reagents may be applied to the array 34 in a
liquid or other form and dried or semi-dried onto the array 34 in
accordance with this disclosure.
[0046] In a separate process, a double-sided pressure-sensitive
film with dual release liners is fed into a window punch unit where
notches are formed. The film is then fed into a lamination &
kiss-cutting station. At the same time, a roll of cover substrate
material is fed over a guide roll into the lamination &
kiss-cutting station, where the release liner is removed from the
upper surface 44 and rewound into a roll. The upper surface 33 of
the spacer substrate material is applied to the cover substrate
material. Next, the film is kiss cut and a portion of the cover
substrate material is removed, leaving behind the cover substrate
material coupled to the spacer substrate material, extending across
a portion of the notch.
[0047] The cover material/spacer substrate subassembly is fed into
a sensor lamination & cut/pack station. The reagent-coated
electrode-support substrate material is fed from the dispensing
station into the sensor lamination & cut/pack station as well.
The remaining release liner is removed from the spacer substrate
and the spacer substrate is positioned on the electrode-support
substrate material so that at least a portion of the electrode
array 36 is aligned with the notch 52. Next, the resulting
assembled material is cut to form individual biosensors 10, which
are sorted and packed into vials, each closed with a stopper, to
give packaged biosensor strips.
[0048] In use, the meter is turned on and the biosensor is inserted
into the meter. It is appreciated that the user may turn on the
meter, or it may turn on automatically upon insertion of the
biosensor. The LED emits a light that is directed through a lens
towards the code pattern of the biosensor. The light is reflected
off of the code pattern, through the lens, and toward the
photodiode. The photodiode measures the intensity of the light that
is reflected back from the code pattern and generates a
corresponding voltage waveform. A decoder deciphers this waveform
and translates it into a reading of the code pattern. It is
appreciated that many commercially available optical readers may be
used in accordance with the present invention. Preferably, the
optical reader will be custom fit reader.
[0049] In use, a user of biosensor 10 places a finger having a
blood collection incision against the recess 35 in the notch 52.
Capillary forces pull a liquid blood sample flowing from the
incision through the capillary channel 60 across the reagent 62 and
the array 34. The liquid blood sample dissolves the reagent 62 and
engages the array 34 where the electrochemical reaction takes
place.
[0050] In use for example, after the reaction is complete, a power
source (e.g., a battery) applies a potential difference between the
electrodes 14, 16 respectively. When the potential difference is
applied, the amount of oxidized form of the mediator at the
reference electrode and the potential difference must be sufficient
to cause diffusion-limited electro-oxidation of the reduced form of
the mediator at the surface of the working electrode. A current
measuring meter (not shown) measures the diffusion-limited current
generated by the oxidation of the reduced form of the mediator at
the surface of the working electrode.
[0051] The measured current may be accurately correlated to the
concentration of the analyte in sample when the following
requirements are satisfied:
[0052] 1. The rate of oxidation of the reduced form of the mediator
is governed by the rate of diffusion of the reduced form of the
mediator to the surface of the working electrode.
[0053] 2. The current produced is limited by the oxidation of
reduced form of the mediator at the surface of the working
electrode.
[0054] The processes and products described above include
disposable biosensor 10 especially for use in diagnostic devices.
Also included, however, are electrochemical sensors for
non-diagnostic uses, such as measuring an analyte in any
biological, environmental, or other sample. As discussed above,
biosensor 10 can be manufactured in a variety of shapes and sizes
and be used to perform a variety of assays, non-limiting examples
of which include current, charge, impedance conductance, potential
or other electrochemical indicative property of the sample applied
to biosensor.
[0055] In accordance with another embodiment of the present
invention, biosensor 110 is illustrated in FIG. 5. Biosensor 110 is
formed in a similar manner to biosensor 10 except that biosensor
110 includes a code pattern 140. Code pattern 140 includes nine
isolated pads 160. It is appreciated that the number of pads can be
greater or fewer than nine in accordance with this disclosure. Each
pad 160 is separated by from the surrounding electrical conductor
by a gap 170.
[0056] Code pattern 140 is used once biosensor 110 is attached to a
meter circuit board (not shown) that includes a connector.
Generally, the connector will include two contacts per possible pad
location on biosensor 110. Code pattern 140 of the present
invention enables the meter to check continuity at each pad 160
location or determine that a pad does not exist in a pre-determined
location. If a pad 160 is present, the meter will recognize the
presence of a pad 160 by a continuity check. One of ordinary skill
in the art will be well aware of methods suitable for performing a
continuity check.
[0057] Code pattern 140 is formed from the electrical conductor by
laser ablation using techniques as described above with reference
to electrodes 14, 16, shown for example in FIG. 1. Specifically,
removing the electrical conductor in a pre-defined pattern to
expose the first surface of the support substrate 12 creates the
code pattern 140. Code pattern 140 can also be coated with a second
electrical conductor (not shown) to modify the electrical
resistivity of the pattern 140. While pattern 140 illustratively
includes nine spaced-apart generally square-shaped pads, it is
appreciated that the pattern 140 can take on any number of shapes
and patterns in accordance with this disclosure. In addition, it is
appreciated that the pattern 140 can be read optically or
electrically in accordance with this disclosure.
[0058] In use, when the user inserts biosensor 110 into the meter
(not shown), the biosensor 1111 makes contact to the connector and
the electronics of the meter inquire as to how many pads 160 are
showing continuity. Predetermined lot information may be stored in
a memory unit of the meter. It is appreciated that the memory unit
may also store a variety of patient information including previous
meter readings. This memory unit is formed with memory components,
a non-limiting example of which is known as RAM, which is well
known in the prior art. The results of the continuity query may be
used to set the appropriate code information in the meter, which
enables the meter to eliminate chemistry or reagent variation.
[0059] In accordance with another embodiment of the present
invention, biosensor 210 is illustrated in FIG. 6. Biosensor 210 is
formed in a similar manner to biosensor 10, except that biosensor
210 includes a code pattern 240. Code pattern 240 includes nine
pads 260 that are in communication with one another. It is
appreciated that the number of pads can vary in accordance with
this disclosure. Each pad 260 is separated from the surrounding
electrical conductor by gaps 270.
[0060] Code pattern 240 is formed from the electrical conductor by
laser ablation using techniques as described above with reference
to electrodes 14, 16, shown for example in FIG. 1. Specifically,
removing the electrical conductor in a pre-defined pattern to
expose the first surface of the support substrate 12 creates the
code pattern 240. Code pattern 240 can also be coated with a second
electrical conductor (not shown) to modify the electrical
resistivity of the pattern 240.
[0061] While pattern 240 illustratively includes nine generally
square-shaped pads that are interconnected, it is appreciated that
the pattern 240 can take on any number of shapes and patterns in
accordance with this disclosure, which would give various
resistance levels. These differing resistance levels can be
correlated to a reagent lot. For example, the pattern 240 can be
varied by disconnecting the internal links between the pads 260.
This disconnection can be done, for example, by a laser. By
changing the number of interconnected pads, the resistance of the
remaining interconnected pads 260 will be different. In addition,
it is appreciated that the pattern 240 can be read optically or
electrically in accordance with this disclosure.
[0062] In use, when the user inserts biosensor 210 into the meter
(not shown), the biosensor 210 makes contact to the connector and
the electronics of the meter inquire as to how many pads 260 are
showing continuity. Information related to this continuity is
similar to that previously described with reference to biosensor
110.
[0063] In addition, the biosensor 210 will make contact with
electronics of the meter, which determines the resistance between
the interconnected pads. Thus, in preferred embodiments, the meter
will determine which pads exist on the biosensor 210, and the
resistance of the interconnected pads 260. The information can be
stored in the meter as described above with reference to biosensors
10 and 110.
[0064] Although the invention has been described in detail with
reference to a preferred embodiment, variations and modifications
exist within the scope and spirit of the invention, on as described
and defined in the following claims.
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