Note: Descriptions are shown in the official language in which they were submitted.
CA 02547681 2007-03-15
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BIOSENSOR
FIELD OF THE INVENTION
The present invention relates to a biosensor, more particularly to an
electrochemical biosensor with a code pattern thereon.
The present invention is a divisional application of Canadian patent
application
Serial No. 2,399,887, filed August 27, 2002.
BACKGROUND AND SUMMARY OF THE INVENTION
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. Patent Nos.
5,413,690;
5,762,770; 5,798,031; and 5,997,817. It is also known to include a code on a
test
strip that identifies the manufacturing batch of the strip. See WO 99/22236.
In accordance with the invention, there is provided a system comprising:
a biosensor comprising:
a support substrate; and
an electrical conductor positioned on the support substrate, the
conductor being disrupted to define at least two electrodes and a code
pattern which includes a plurality of possible pad locations, each possible
pad location comprising a pad comprising:
the electrical conductor separated from surrounding electrical
conductor by a gap, or
an exposed portion of the support substrate;
a meter including a connector comprising two contacts per possible
pad location;
wherein the connector contacts each possible pad location when the
biosensor is inserted in the meter, and the meter has electronics that check
continuity at each possible pad location to determine the presence of the pad.
CA 02547681 2002-08-27
la
In accordance with another aspect of the invention, there is provided a system
comprising:
a biosensor comprising:
a support substrate; and
an electrical conductor positioned on the support substrate, the conductor
being disrupted to define at least two electrodes and a code pattern which
includes a plurality of pads comprising the electrical conductor separated
from the surrounding electrical conductor by a gap, at least one pad being
in communication with at least one other pad by at least one internal link;
a meter including a connector comprising a contact for each pad;
wherein the connector contacts each pad when the biosensor is inserted in the
meter, and the meter has electronics that check continuity between
interconnected pads.
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 at least one reagent positioned on
at least one
electrode.
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.
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
an 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.
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
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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.
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
The detailed description particularly refers to the accompanying figures in
which:
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.
Fig. 2 is azi 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.
Fig. 3 is a view taken along lines 3-3 of Fig. 1.
Fig. 4 is a view taken along lines 4-4 of Fig. 1.
Fig. 5 is an enlarged top view of an alternative code pattern formed on a
biosensor in
accordance with the present invention.
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
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
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also be high reflectivity areas surrounded by low reflectivity areas or vice
yersa, 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.
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.
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 , a
PEN film
commercially available from E.I. DuPont de Nemours, Wilmington, Delaware,
which is coated
with gold by ROWO Coating, Henbolzhelm, Germany.
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
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noble metals and their alloys are unreactive in biological systems. Most
preferably, electrical
conductor 13 is gold.
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 No. 6,662,439, entitled "LASER DEFINED FEATURES
FOR
PATTERNED LAMINATES AND ELECTRODE". 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 m
to about 500 m, preferably the gap has a width of about 100 m to about 200
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.
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.
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.
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 con-
ductor 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
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can take on any number of shapes and patterns, non-limiting examples of which
are shown in
Figs. 5 and 6.
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
5 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.
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.
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 pm to about 1000
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.
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.
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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.
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, Pennsylvania.
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.
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.
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, MN.
Referring now to Figs. l 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.
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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.
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.
Patent No. 5,997,817.
Non-limiting examples of enzymes and mediators that may be used in measuring
particular
analytes in biosensor 10 are listed below in Table 1.
* trade-mark
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TABLE 1
Analyte Enzymes Mediator Additional Mediator
(Oxidized Form)
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
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.
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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.
Biosensor 10 is used in conjunction with the following:
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
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.
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.
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
CA 02547681 2002-08-27
al., U.S. Pat. No. 5,438,271, issued Aug. 1, 1995.
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
5 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.
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
10 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.
In the laser ablation station, the metallic layer of the metallized film is
ablated at 70 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/cm2 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.
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. Patent No.
5,762,770. 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.
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-
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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.
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.
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.
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.
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
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12
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.
The measured current may be accurately correlated to the concentration of the
analyte in
sample when the following requirements are satisfied:
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.
2. The current produced is limited by the oxidation of reduced form of the
mediator at
the surface of the working electrode.
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.
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.
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.
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
CA 02547681 2002-08-27
13
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.
In use, when the user inserts biosensor 110 into the meter (not shown), the
biosensor 110
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.
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.
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.
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.
CA 02547681 2002-08-27
14
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.
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.
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.
