Title of Invention

A ELECTROCHEMICAL CELL AND A METHOD FOR FORMING AN ELECTRICAL CONNECTION BETWEEN A CELL AND A METER .

Abstract The present invention relates to electrochemical cells including a connector which mates with a connection device to provide electrical connection to meter circuitry.
Full Text Field of the Invention
The present invention relates to electrochemical cells including a connector which
mates with a meter connection device to provide electrical connection to meter circuitry.
Background of the Invention
Miniature electrochemical cells are useful in applications such as chemical sensing
wherein the electrodes of a strip element interface with an electronic device. The electronic
device, often termed a meter, measures the electrical response of the strip element to the
sample and can also supply power to the strip element to perform a test. In order to
perform these functions, the strip element electrodes must be able to make electrical
connection to the meter circuitry. Such an electrical connection may be made via a
connection device on the meter which mates with areas on the strip element in electrical
communication with the electrochemical cell electrodes.
In configurations of electrochemical cells as disclosed in WO 98/43073, U.S.
5,437,999, EP 0 964 059 A2, WO 00/20626, an upper and a lower electrode face oppose
one another with an electrically insulating layer between them. The electrodes in such a
configuration are typically formed on separate substrates that are assembled during
manufacture of the electrochemical cell. This configuration presents difficulties in
manufacture when forming a part by which the strip element electrodes are connected to the
meter circuitry, as it is different from the usual connection configuration where the
connection areas are all on the same plane.
The issue of connection areas in different planes has been addressed in various
ways, hi WO 98/43073, a method and device are disclosed wherein cut-outs are formed in
one of the electrode layers and in the insulating layer to expose an area of the underlying
electrode layer which can be used as an connection area. In U.S. 5,437,999 and WO
00/20626, a method an device are disclosed wherein a flap is formed on one electrode layer
with a corresponding cut-out in the other electrode layer to expose a suitable connection
area. In this configuration, the insulating layer is cut short so as not interfere with the
connection area.
In EP 0 964 059 A2, the insulating layer is cut short, and a hole is formed in the
upper substrate in order to expose a connection area at the base of the well that is formed.
The well may be filled with a conductive material and a contact made with the conductive
material at the top of the filled well, thus bringing the connection areas onto one plane,
A drawback to these configurations is that they require features on more than one of
the cell layers to be in registration with one another when the layers are assembled into a
working device. This creates difficulties in manufacturing ihe devices and limits the
manufacturing techniques that can be used. In particular, for costs and throughput
considerations, it is often desirable to manufacture the strip elements in a continuous web
form. When using continuous webs it is often difficult to reliably achieve the down-web
registration of repeating features formed on different layers prior to a lamination step.
Often this requires expensive control systems and a relatively fragile fabrication process, if
it is possible at all.
Summary of the Invention
Electrochemical cell connectors that are suitable for use in conjunction with
opposing electrode electrochemical cells, and methods of forming them, that require no
down-web registration steps prior to lamination of the layers are desirable. The preferred
embodiments provide such electrochemical cell connectors and methods.
In a first embodiment, an electrochemical cell is provided, the electrochemical cell
adapted for electrical connection with a meter, the cell including a first insulating substrate
carrying a first electrically conductive coating, a second insulating substrate carrying a
second electrically conductive coating, and an insulating spacer layer disposed
therebetween, the electrically conductive coatings being disposed to face each other in a
spaced apart relationship, wherein an edge of the first insulating substrate carrying the first
electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating
spacer layer, and wherein the edge of the second insulating substrate carrying the second
electrically conductive coating extends beyond the edge of the insulating spacer layer.
In an aspect of the first embodiment, the first insulating substrate carrying the first
electrically conductive coating includes an aperture in a portion of the first insulating
substrate carrying the first electrically conductive coating that extends beyond the edge of
the insulating spacer, such that an area of the second electrode layer is exposed so as to
provide a surface for forming an electrical connection with a meter via the aperture.
In an aspect of the first embodiment, the cell further includes an additional
insulating spacer layer, the additional spacer layer disposed between the first electrically
conductive coating and the second electrically conductive coating, wherein the insulating
spacer layer and the additional spacer layer are situated on opposite sides of the aperture.
In a second embodiment, an electrochemical cell is provided, the electrochemical
cell adapted for electrical connection with a meter, the cell including a first insulating
substrate carrying a first electrically conductive coating, a second insulating substrate
carrying a second electrically conductive coating, and an insulating spacer layer disposed
therebetween, the electrically conductive coatings being disposed to face each other in a
spaced apart relationship, wherein an edge of the first insulating substrate carrying the first
electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating
spacer layer, and wherein the first insulating substrate carrying the first electrically
conductive coating and the insulating spacer layer include an aperture, such that an area of
the second electrode layer is exposed so as to provide a surface for forming an electrical
connection with a meter via the aperture.
In a third embodiment, an electrochemical cell is provided, the electrochemical cell
adapted for electrical connection with a meter, the cell including a first insulating substrate
carrying a first electrically conductive coating, a second insulating substrate carrying a
second electrically conductive coating, and an insulating spacer layer disposed
therebetween, the electrically conductive coatings being disposed to face each other in a
spaced apart relationship, wherein a portion of the first insulating substrate carrying the first
electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating
spacer layer, and wherein a portion of the first insulating substrate carrying the first
electrically conductive coating and a portion of the insulating spacer are removed so as to
form a notch, die notch situated adjacent to the edge of the second insulating substrate
carrying the second electrically conductive coating and the edge of the insulating spacer
layer, such that an area of the second electrode layer is exposed so as to provide a surface
for forming an electrical connection with a meter.
In a fourth embodiment, a method for forming an electrical connection between an
electrochemical cell and a meter is provided, the method including the steps of: providing
an electrochemical cell, the electrochemical cell comprising a first insulating substrate
carrying a first electrically conductive coating, a second insulating substrate carrying a
second electrically conductive coating, and an insulating spacer layer disposed
therebetween, the electrically conductive coatings being disposed to face each other in a
spaced apart relationship, wherein an edge of the first insulating substrate carrying the first
electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating
spacer layer, and wherein the edge of the second insulating substrate carrying the second
electrically conductive coating extends beyond the edge of the insulating spacer layer;
providing a meter, the meter including a wedge, the wedge including an upper wedge
conductive surface and a lower wedge conductive surface, the conductive surfaces in
electrical communication with the meter; and inserting a portion of the electrochemical cell
into the meter, whereby the wedge is inserted between the portion of the first insulating
substrate carrying the first electrically conductive coating and the portion of the second
insulating substrate carrying the second electrically conductive coating that extends beyond
the edge of the insulating spacer layer, whereby an electrical connection between the first
electrically conductive coating and the lower wedge conductive surface is formed, and
whereby an electrical connection between the second electrically conductive coating and
the upper wedge conductive surface is formed.
In an aspect of the fourth embodiment, the meter further includes a pivot point,
wherein the wedge is capable of rotating on the pivot point.
Brief Description of the! Drawings
Figures 1a and 1b provide schematics of an electrochemical cell wherein element 2
is offset from the corresponding edge of element 1 so as to expose the conductive coating
on element 1. Figure 1a illustrates a top view and Figure 1b a cross-section view.
Figures 2a and 2b provide schematics of an electrochemical cell wherein a through
hole is cut in element 1 to expose the conductive coating on element 2 for electrical
connection. Figure 2a illustrates a top view and Figure 2b a cross-section view.
Figures 3a and 3b provide schematics of an electrochemical cell similar to the cell
of Figure 2, except that an extra portion of element 3 has been inserted between elements 1
and 2. Figure 3a illustrates a top view and Figure 3b a cross-section view.
Figures 4a and 4b provide schematics of an electrochemical cell wherein a slot is
formed in element 1, which gives access to an area of the conductive coating on element 2.
Figure 4a illustrates a top view and Figure 4b a cross-section view.
Figures 5a and 5b provide schematics of an electrochemical cell similar to the cell
of Figure 2, except that the edge of element 3 is such that it is situated above element 4 in
element 1. Figure 5a illustrates a top view and Figure 5b a cross-section view.
Figures 6a and 6b provide schematics of an electrochemical cell similar to the cell
of Figure 4, except that the edge of element 3 is such that it is at least close to the edge of
element 1. Figure 6a illustrates a top view and Figure 6b a cross-section view.
Figure 7 provides a side view illustrating the splitting of element 1 from element 2
in the connector area to allow access for a tongue connection device.
Figure 8 provides an end view illustrating the splitting of element 1 from element 2
in the connector area to allow access for a tongue connection device.
Figure 9 provides an illustration depicting a strip partially inserted into an external
circuit connector.
Figure 10 provides an illustration depicting a strip fully inserted into an external
circuit connector.
Figure 11 provides a side view of an external circuit connector 100.
Figure 12 provides an illustration depicting a strip partially inserted into an external
circuit connector 100 as illustrated in Figure 11.
Figure 13 provides an illustration depicting a strip fully inserted into an external
circuit connector 100 as illustrated in Figure 11.
Detailed Description of the Preferred Embodiment
The following description and examples illustrate a preferred embodiment of the
present invention in detail. Those of skill in the art will recognize that there are numerous
variations and modifications of this invention that are encompassed by its scope.
Accordingly, the description of a preferred embodiment should not be deemed to limit the
scope of the present invention.
The preferred embodiments relate to devices and methods for forming electrode
connection areas in electrochemical cells with opposing electrodes. The devices and
methods do not require the registration of features formed on different layers prior to the
lamination of the layers. In particular, devices and methods that do not require the down-
web registration of repeating features on different layers during lamination of continuous
webs of devices during manufacture are provided. The preferred embodiments may be used
in conjunction with any suitable fabrication process, for example, a process wherein
discrete sections of the layers are laminated together and wherein it is advantageous to
lessen the registration requirements and therefore the manufacturing complexity.
In another embodiment, preferred elements of the port in a meter device suitable for
use with the disclosed strip connectors are provided.
The basic feature of the electrochemical cells illustrated in Figures 1-6 is that the
edge of at least one electrode layer (herein termed the upper electrode layer) is offset from
at least one other opposing electrode layer (here termed the lower electrode layer) such that
an area of the lower electrode layer overhangs the edge of the upper electrode layer, thus
exposing an area of the lower electrode layer suitable for connection to meter circuitry.
Figures 1 to 6 depict views of various preferred embodiments of electrochemical
cell connectors. Figures la, 2a, 3a, 4a, 5a, and 6a depict top views of sections of web or
card of the assembled layers for various embodiments, showing the repeating features.
Figures 1b, 2b, 3b, 4b, 5b, and 6b depict the corresponding cross-sectional views.
In Figures 1 to 6, element 1 is the lower electrode layer. This layer consists of an
electrically insulating substrate with an electrically conductive coating applied to its upper
face, wherein the electrically conductive coating is in electrical contact with at least a first
electrode of the electrochemical cell.
Element 2 is the upper electrode layer. This layer consists of an electrically
insulating substrate with an electrically conductive coating applied to its lower face,
wherein the electrically conductive coating is in electrical contact with at least a second
electrode of the electrochemical cell.
Element 3 is an electrically insulating layer which serves to space elements 1 and 2
apart. In preferred embodiments, the upper and lower faces of element 3 are adhesive and
also serve to adhere the layers of the device together. In this preferred embodiment,
element 3 may consist of a substrate coated with an adhesive. Alternatively it may consist
of just an adhesive layer.
Element 4 is a cut-out feature in element 1 which, as illustrated in Figures 2 to 6,
serves to give access to an exposed area of the electrically conductive coating on the lower
face of element 2.
In Figure 1, one edge of element 2 is offset from the corresponding edge of element
1, such that an overhanging area of the conductive coating on element 1 is exposed. In a
preferred embodiment, a tongue of electrically insulating substrate material with electrically
conductive coatings or layers on its upper and lower feces is inserted between elements 1
and 2 to make electrical connection to the meter circuitry.
In Figure 2, a through hole is cut in element 1 to expose an area of the conductive
coating on element 2 for electrical connection. This obviates the need for having a
connection device inserted between the layers.
The device depicted in Figure 3 is similar to that depicted in Figure 2, except that an
extra portion of element 3 has been inserted between elements 1 and 2. This configuration
is desirable if it is likely that elements 1 and 2 will be pushed together during use and thus
create an electrical short-circuit between the conductive coatings on elements 1 and 2.
Figure 4 depicts an embodiment where a slot has been formed in element 1 which
gives access to an area of the conductive coating on element 2.
Figure 5 depicts a similar embodiment to Figure 2. However in this embodiment
the edge of element 3 is such that it is above element 4 in element 1. In order for this
embodiment to be operable in the preferred embodiment elements 1 and 2 must be
laminated or otherwise assembled together before element 4 is formed.
Figure 6 depicts a similar embodiment to Figure 4. However in this embodiment
the edge of element 3 is such that it is at least close to the edge of element 1. In this
embodiment, it is preferred that elements 1 and 2 be laminated or otherwise assembled
together before element 4 is formed.
In another embodiment, methods are disclosed for forming electrical connections to
some of the connection devices discussed above.
For the electrochemical cells of the preferred embodiments depicted in Figures 2 to
6, it is suitable to use parts for the connection of the conductive coatings on elements 1 and
2 to external circuitry such as those described in copending U.S. patent application
09/399,512 filed on September 20,1999.
For the embodiment depicted in Figure 1, a different configuration for external
connection is desirable. For this embodiment, it is desirable to split element 1 from
element 2 in the connector area to allow easier access for a tongue connection device.
According to this aspect of the embodiment, element 1 is split from element 2 during
insertion of the strip connector into external circuitry connector, e.g., by a blade or wedge-
shaped projection, or other suitable splitting device.
Figures 7 and 8 show a side view and end view, respectively, that illustrate the
splitting of element 1 from element 2 in the connector area to allow access for a tongue
connection device. Figures 9 and 10 show this embodiment with a strip partially and folly
inserted, respectively, into the external circuit connector.
The external circuit connector 10, depicted in Figures 7 to 10, contains a chamber
18, which contains cavities 11 and 12 into which element 1 and element 2, respectively, of
the strip can be inserted. One or more wedge shaped projections 17 on the sidewalls of
chamber 18 serve to separate strip elements 1 and 2 as the strip is inserted into chamber 18.
As the strip is inserted into chamber 18, element 1 first strikes the lower face of projection
17 and is forced down. This action in concert with the insertion action serves to further
separate element 1 from element 2 to allow reliable insertion of element 2 into cavity 12.
A further wedge-shaped projection protrudes from the rear face of chamber 18.
Conducting layers are mounted on the faces 13 and 14 of this projection, wherein the two
conducting layers are electrically insulated from one another. These layers make electrical
contact with the conducting coatings on strip elements 1 and 2. Electrically conducting
wires or other conducting tracks 15 and 16 are electrically connected to the conducting
layers on faces 13 and 14 and serve to make connection to the external circuitry. As one
skilled in the art will appreciate, the device with surfaces comprising conducting layers 13
and 14 may be constructed so as to be integral with the projections 17.
A second embodiment is depicted in Figures 11 to 13. Figure 11 shows a side view
of the embodiment. Figures 12 and 13 show a side view of the embodiment with a strip
partially or fully inserted respectively.
The external circuit connector 100, depicted in Figures 11 to 13, contains a chamber
105 which contains a wedge 101 that is able to rotate within the chamber 105 around the
pivot point 102. The wedge comprises electrically conductive surfaces, 106 and 107 which
are electrically connected to external connection points 103 and 104. In its initial position,
the wedge 101 is held either by gravity or a spring tensioning device (not shown) such that
it is positioned as shown in Figure 11. When a strip is inserted into the chamber 105, the
lower electrode element strikes the lower surface of wedge 101 behind the pivot point 102.
This action rotates wedge 101 such that the point of the wedge 101 is positioned between
the upper and lower electrode layers of the strip. Then, as the strip is further inserted into
chamber 105, the upper wedge surface 106 is brought into contact with the conducting
coating on the upper strip element. Electrical connection of the conducting coating on the
upper strip element to connection point 103, via conducting surface 106 is then achieved, as
is electrical connection of the conducting coating on the lower electrode strip element to
connection point 104 via conducting surface 107.
The advantage of the embodiment shown in Figures 11 to 13 is that the point of the
wedge 101 is automatically positioned between the upper and lower strip electrode
elements to ensure reliable connection.
Electrochemical cells
The electrochemical cell connectors of preferred embodiments are suitable for use
in a variety of electrochemical cells. For example, the connectors may be used in
conjunction with electrochemical cells used as amperometric sensors for the detection and
quantification of analytes.
In such applications, the electrodes can be positioned such that the working
electrode is isolated from the counter electrode reactions and reaction products, or
positioned such that products of the counter electrode reaction diffuse to the working
electrode where they react. The former type of electrochemical cell is well known in the
prior art. The latter type of electrochemical cell is discussed in US 6,179,979 and US
5,942,102.
These two electrode configurations vary in that in the isolated case, the counter
electrode is positioned far enough away from the working electrode such that during the
time the cell is being used, products of electrochemical reactions at the counter electrode do
not reach the working electrode. In practice, this is typically achieved by a separation of the
working electrode from the counter electrode by at least a millimeter.
In the non-isolated configuration, the working electrode and the counter electrode
are placed close enough together such mat products of the electrochemical reactions at the
counter electrode can diffuse to the working electrode during the time the cell is being used.
These reaction products can then react at the working electrode, giving a higher current than
may be present in the isolated electrode case. In the non-isolated configuration, the
working electrode reactions can be described as coupled to the counter electrode reactions.
Fabricating the Electrochemical Cell
In certain embodiments, the electrochemical cells of preferred embodiments may be
fabricated using methods similar to those disclosed in U.S. 5,942,102.
As will be recognized by one skilled in the art, the electrode layers and electrically
insulating substrates may be independently selected as desired, for example, for ease of
fabrication, for reducing materials costs, or to achieve other desirable attributes of the cell
or fabrication process. Likewise, the electrode layers may be applied to the layers of
electrically insulating substrates in any suitable pattern, for example, a pattern that only
partially covers the substrate.
In preferred embodiments, various layers in the cell may be adhered using a suitable
adhesive. Suitable adhesives include, for example, heat activated adhesives, pressure
sensitive adhesives, heat cured adhesives, chemically cured adhesives, hot melt adhesives,
hot flow adhesives, and the like. Pressure sensitive adhesives are preferred for use in
certain embodiments where simplification of fabrication is desired. However, in other
embodiments the tackiness of pressure sensitive adhesives may result in fabrication tool
gumming or product tackiness. In such embodiments, heat or chemically cured adhesives
are generally preferred. Especially preferred are the heat-activated and heat-cured
adhesives, which can be conveniently activated at the appropriate time.
In certain embodiments, it may be preferred to use a hot melt adhesive. A hot melt
adhesive is a solvent-free thermoplastic material that is solid at room temperature and is
applied in molten form to a surface to which it adheres when cooled to a temperature below
its melting point. Hot melt adhesives are available in a variety of chemistries over a range
of melting points. The hot melt adhesive can be in the form of a web, nonwoven material,
woven material, powder, solution, or any other suitable form. Polyester hot melt adhesives
may be preferred for certain embodiments. Such adhesives (available, for example, from
Bostik Corp. of Middleton, MA) are linear saturated polyester hot melts exhibiting melting
points from 65°C up to 220°C and range from completely amorphous to highly crystalline
in nature. Polyamide (nylon) hot melt adhesives, also available from Bostik, may also be
preferred, including both dimer-acid and nylon-type polyamide adhesives. Suitable hot
melt adhesive chemistries include EVA, polyethylene, and polypropylene.
Alternatively, in certain other embodiments it may be preferred to use lamination
techniques to bond certain layers together. Suitable lamination techniques are described in
Application No. 09/694,106 filed October 20, 2000 and Application No. 09/694,120 filed
October 20,2000, each entitled "LAMINATES OF ASYMMETRIC MEMBRANES." The
layers to be laminated are placed adjacent to each other and heat is applied, whereby a bond
between the layers is formed. Pressure may also be applied to aid in forming the bond.
Lamination methods may be preferred to bond any two materials capable of forming a bond
under application of heat and/or pressure. Lamination is preferred to form a bond between
two suitable polymeric materials.
Suitable electrically resistive materials which may be preferred as spacer layers, as
supports for electrode layers, or in other layers in the cell, include, for example, materials
such as polyesters, polystyrenes, polycarbonates, polyolefins, polyethylene terephthalate,
glasses, ceramics, mixtures and/or combinations thereof, and the like. Examples of
electrically resistive adhesives suitable for use as spacer or support layers include, but are
not limited to, polyacrylates, polymethacrylates, polyurethanes, and sulfonated polyesters.
Chemicals for use in the cell, such as redox reagents, lysing agents, buffers, inert
salts, and other substances, may be supported on the cell electrodes or walls, on one or
more independent supports contained within cell, or may be self supporting. If the
chemicals are to be supported on the cell electrodes or walls, the chemicals may be applied
by use of application techniques well known in the art, such as ink jet printing, screen
printing, lithography, ultrasonic spraying, slot coating, gravure printing, and the like.
Suitable independent supports may include, but are not limited to, meshes, nonwoven
sheets, fibrous fillers, macroporous membranes, and sintered powders. The chemicals for
use in the cell may be supported on or contained within a support.
In a preferred embodiment, the preferred materials within the cell as well as the
materials from which the cell is constructed are in a form amenable to mass production, and
the cells themselves are designed for a single experiment then disposed of. A disposable
cell is one that is inexpensive enough to produce that it is economically acceptable only for
a single test. A disposable cell is one that may conveniently only be used for a single test,
namely, steps such as washing and/or reloading of reagents may need to be taken to process
the cell after a single use to render it suitable for a subsequent use.
Economically acceptable in this context means that the perceived value of the result
of the test to the user is the same or greater than the cost of the cell to purchase and use, the
cell purchase price being set by the cost of supplying the cell to the user plus an appropriate
mark up. For many applications, cells having relatively low materials costs and simple
fabrication processes are preferred. For example, the electrode materials of the cells may
be inexpensive, such as carbon, or may be present in sufficiently small amounts such that
expensive materials may be preferred. Screen printing carbon or silver ink is a process
suitable for forming electrodes with relatively inexpensive materials. However, if it is
desired to use electrode materials such as platinum, palladium, gold, or iridium, methods
with better material utilization, such as sputtering or evaporative vapor coating, are
preferred as they may yield extremely thin films. The substrate materials for the disposable
cells are also preferably inexpensive. Examples of such inexpensive materials are polymers
such as polyvinylchloride, polyimide, polyester and coated papers and cardboard.
Cell assembly methods are preferably amenable to mass production. These methods
include fabricating multiple cells on cards and separating the card into individual strips
subsequent to the main assembly steps, and web fabrication where the cells are produced on
a continuous web, which is subsequently separated into individual strips. Card processes
are most suitable when close spatial registration of multiple features is desired for the
fabrication and/or when stiff cell substrate materials are preferred. Web processes are most
suitable when the down web registration of features is not as critical and flexible webs may
be preferred.
In certain embodiments, a convenient single use for the electrochemical cell may be
desirable so that users are not tempted to try to reuse the cell and possibly obtain an
inaccurate test result. Single use of the cell may be stated in user instructions
accompanying the cell. More preferably, in certain embodiments where a single use is
desirable the cell may be fabricated such that using the cell more than once is difficult or
not possible. This may be accomplished, for example, by including reagents mat are
washed away or consumed during the first test and so are not functional in a second test.
Alternatively, the signal of the test may be examined for indications that reagents in the cell
have already reacted, such as an abnormally high initial signal, and the test aborted.
Another method includes providing a means for breaking electrical connections in the cell
after the first test in a cell has been completed.
The Electrodes
In a preferred embodiment wherein the electrochemical cell detects the presence
and/or amount of analyte in the sample, or a substance indicative of the presence and/or
amount of analyte present in the sample, at least one of the electrodes in the cell is a
working electrode. When the potential of the working electrode is indicative of the level of
analyte (such as in a potentiometric sensor) a second electrode acting as reference electrode
is present which acts to provide a reference potential.
In the case of an amperometric sensor wherein the working electrode current is
indicative of the level of an analyte, such as glucose, at least one other electrode is
preferably present which functions as a counter electrode to complete the electrical circuit
This second electrode may also function as a reference electrode. Alternatively, a separate
electrode may perform the function of a reference electrode.
Materials suitable for the working, counter, and reference electrodes are compatible
with any reagents or substances present in the device. Compatible materials do not
substantially react chemically with other substances present in the cell. Examples of such
suitable materials may include, but are not limited to, carbon, carbon and an organic binder,
platinum, palladium, carbon, indium oxide, tin oxide, mixed indium/tin oxides, gold, silver,
iridium, and mixtures thereof. These materials may be formed into electrode structures by
any suitable method, for example, by sputtering, vapor coating, screen printing, thermal
evaporation, gravure printing, slot coating or lithography. In preferred embodiments, the
material is sputtered or screen-printed to form the electrode structures.
Non-limiting examples of materials preferred for use in reference electrodes include
metal/metal salt systems such as silver in contact with silver chloride, silver bromide or
silver iodide, and mercury in contact mercurous chloride or mercurous sulfate. The metal
may be deposited by any suitable method and then brought into contact with the appropriate
metal salt. Suitable methods include, for example, electrolysis in a suitable salt solution or
chemical oxidation. Such metal/metal salt systems provide better potential control in
potentiometric measurement methods than do single metal component systems. In a
preferred embodiment, the metal/metal salt electrode systems are preferred as a separate
reference electrode in an amperometric sensor.
Any suitable electrode spacing may be used. In certain embodiments it may be
preferred that the electrodes be separated by a distance of about 500 µm, 400 µm, 300 µm,
200 µm, 100 µm, 50 µm, 200 µm, 10 µm, or tess. In other embodiments it may be
preferred that the electrodes be separated by a distance of about 500 µm, 600 µm, 700 µm,
800 µm, 900 µm, 1 mm, or more.
Lysing Agents
In certain embodiments, it may be desired to include one or more lysing agents in
the electrochemical cell. Suitable lysing agents include detergents, bom ionic and non-
ionic, proteolytic enzymes, and lipases. Suitable ionic detergents include, for example,
sodium dodecyl sulfate and cetyl trimethylammonium bromide. Non-limiting examples of
proteolytic enzymes include trypsin, chymotrypsin, pepsin, papain, and Pronase E, a very
active enzyme having broad specificity. Nonionic surfactants suitable for use include, for
example, ethoxylated octylphenols, including the TRTTON X™ Series available from
Rohm & Haas of Philadelphia, Pennsylvania. In a preferred embodiment, saponins,
namely, plant glycosides that foam in water, are preferred as the lysing agent. In a
particularly preferred embodiment, alkali metal salts of deoxycholic acid, available from
Sigma Aldrich Pty. Ltd. of Castle Hill, NSW, Australia, are preferred as lysing agents.
Redox Reagent
Redox reagents may also be included in the electrochemical cell in preferred
embodiments. Preferred redox reagents for use in electrochemical cells for measuring
glucose in blood include those which are capable of oxidizing the reduced form of enzymes
that are capable of selectively oxidizing glucose. Examples of suitable enzymes include,
but are not limited to, glucose oxidase dehydrogenase, PQQ dependent glucose
dehydrogenase, and NAD dependent glucose dehydrogenase. Examples of redox reagents
suitable for use in analyzing glucose include, but are not limited, to salts of ferricyanide,
dichromate, vanadium oxides, permanganate, and electroactive organometallic complexes.
Organic redox reagents such as dichlorophenolindophenol, and quinones are also suitable.
In a preferred embodiment, the redox reagent for analyzing glucose is ferricyanide.
Buffers
Optionally, a buffer may be present along with a redox reagent in dried form in the
electrochemical cell. If a buffer is present, it is present in an amount such that the resulting
pH level is suitable for adjusting the oxidizing potential of the redox reagent to a level
suitable for oxidizing, for example, glucose but not other species that it is not desired to
detect. The buffer is present in a sufficient amount so as to substantially maintain the pH of
the sample at the desired level during the test. Examples of suitable buffers include
phosphates, carbonates, alkali metal salts of mellitic acid, alkali metal salts of citric acid,
and alkali metal salts of citraconic acid. The choice of buffer may depend, amongst other
factors, on the desired pH. The buffer is selected so as not to react with the redox reagent.
Inert Salts
Inert salts preferred for use in various embodiments include salts that dissociate to
form ions in the sample to be analyzed, but do not react with any of the redox reagents or
other substances in the sample or in the cell, including with the cell electrodes. Examples
of suitable inert salts include, but are not limited to, alkali metal chlorides, nitrates, sulfates,
and phosphates.
Other Substances Present Within the Cell
In addition to redox reagents and buffers, other substances may also be present
within the electrochemical cell. Such substances include, for example, viscosity enhancers
and low molecular weight polymers. Hydrophilic substances may also be contained within
the cell, such as polyethylene glycol, polyacrylic acid, dextran, and surfactants such as those
marketed by Rohm & Haas Company of Philadelphia, Pennsylvania, under the trade name
TRITON™ or by ICI Americas Inc. of Wilmington, Delaware, under the trade name
TWEEN™. In a preferred embodiment Pluronic surfactants and antifoaming agents
available from BASF are present. Such substances may enhance the fill rate of the cell,
provide a more stable measurement, and inhibit evaporation in small volume samples.
Electrical Circuit
The electrically conductive layers are preferably connected via the connectors
described herein to electrical circuits capable of applying potentials between die electrodes
and measuring the resulting currents, for example, meters. Suitable meters may include one
or more of a power source, circuitry for applying controlled potentials or currents, a
microprocessor control device, computer, or data storage device, a display device, an
audible alarm device, or other devices or components as are known in the art. The meter
may also be capable of being interfaced to a computer or data storage device. For example,
a typical meter may be a hand-held device that is powered by a battery, controlled by an on-
board microprocessor, and contains circuitry for applying predetermined potentials or
currents between, for example, strip electrode connection pins and circuitry such as an
analog-to-digital converter. In this embodiment, the analog signal from the strip may be
converted to a digital signal that can be analyzed and/or stored by a microprocessor. The
meter may also contain a display such as a Liquid Crystal Display and suitable associated
circuitry to display the result of the test to the user. In an alternative embodiment, the meter
may incorporate specialized circuitry, such as potential application and signal acquisition
circuitry. Such specialized circuitry may be incorporated in a separate module that may be
interfaced with a generic computing device, such as a hand-held computer or other type of
computer. In such an embodiment, the generic device may perform the control, analysis,
data storage, and/or display functions. Such an embodiment allows for a less expensive
meter to be produced because the generic computing device may be preferred for many
functions and as such is not considered as part of the cost of the electrochemical
measurement system. In either of these meter embodiments, the meter or generic
computing device may be capable of communication with external devices such as local
computer networks or the Internet to facilitate the distribution of test results and the
provision of system upgrades to the user.
The above description provides several methods and materials of the present
invention. This invention is susceptible to modifications in the methods and materials, as
well as alterations in the fabrication methods and equipment. Such modifications will
become apparent to those skilled in the art from a consideration of this disclosure or
practice of the invention provided herein. Consequently, it is not intended that this
invention be limited to the specific embodiments provided herein, but that it cover all
modifications and alternatives coming within the true scope and spirit of the invention as
embodied in the attached claims. All references cited herein are hereby incorporated by
reference in their entireties.
1. An electrochemical cell, the electrochemical cell adapted for electrical connection with a meter,
the cell comprising a first insulating substrate carrying a first electrically conductive coating, a
second insulating substrate carrying a second electrically conductive coating, and an insulating
spacer layer disposed therebetween, the electrically conductive coatings being disposed to face
each other in a spaced apart relationship, wherein an edge of the first insulating substrate carrying
the first electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating spacer
layer, and wherein the edge of the second insulating substrate and carrying the second electrically
conductive coating extends beyond the edge of the insulating spacer layer.
2. The electrochemical cell of claim 1, wherein the first insulating substrate carrying the first
electrically conductive coating comprises an aperture in a portion of the first insulating substrate
carrying the first electrically conductive coating that extends beyond the edge of the insulating
spacer, such that an area of the second electrode layer is exposed so as to provide a surface for
forming an electrical connection with a meter via the aperture.
3. The electrochemical cell of claim 2, comprising an additional insulating spacer layer, the
additional spacer layer disposed between the first electrically conductive coating and the second
electrically conductive coating, wherein the insulating spacer layer and the additional spacer layer
are situated on opposite sides of the aperture.
4. An electrochemical cell, the electrochemical cell adapted for electrical connection with a meter,
the cell comprising a first insulating substrate carrying a first electrically conductive coating, a
second insulating substrate carrying a second electrically conductive coating, and an insulating
spacer layer disposed therebetween, the electrically conductive coatings being disposed to face
each other in a spaced apart relationship, wherein an edge of the first insulating substrate-carrying
the first electrically conductive coating extends beyond an edge of the second insulating substrate
carrying the second electrically conductive coating and beyond an edge of the insulating spacer
layer, and wherein the first insulating substrate carrying the first electrically conductive coating
and the insulating spacer layer comprise an aperture, such that an area of the second electrode
layer is exposed so as to provide a surface for forming an electrical connection with a meter via
the aperture.
5. An electrochemical cell, the electrochemical cell adapted for electrical connection with a meter,
the cell comprising a first insulating substrate carrying a first electricity conductive coating, a
second insulating substrate carrying a second electrically conductive coating, and an insulating
spacer layer disposed therebetween, the electrically conductive coatings being disposed to face
each other in a spaced apart relationship, wherein a portion of the first insulating substrate
carrying the first electrically conductive coating extends beyond an edge of the second insulating
substrate carrying the second electrically conductive coating and beyond an edge of the insulating
spacer layer, and wherein a portion of the first insulating substrate carrying the first electrically
conductive costing and a portion of the insulating spacer are removed so as to form a notch, the
notch situated adjacent to the edge of the second insulating substrate carrying the second
electrically conductive coating and the edge of the insulating spacer layer, such that an area of the
second electrode layer is exposed so as to provide a surface for forming an electrical connection
with a meter.
6. A method for forming an electrical connection between an electrochemical cell and a meter, the
method comprising the steps of:
a) providing an electrochemical cell, the electrochemical cell comprising a first insulating
substrate carrying a first electrically conductive coating, a second insulating substrate
carrying a second electrically conductive coating, and an insulating spacer layer disposed
therebetween, the electrically conductive coatings being disposed to face such other in a
spaced apart relationship, wherein an edge of the first insulating substrate carrying the
first electrically conductive coating extends beyond an edge of the second insulating
substrate carrying the second electrically conductive coating and beyond edge of the
insulating spacer layer, and wherein the edge of the second insulating substrate carrying
the second electrically conductive coating extends beyond the edge of the insulating
spacer layer;
b) providing a meter, the meter comprising a wedge, the wedge comprising an upper wedge
conductive surface and a lower wedge conductive surface, the conductive surfaces in
electrical communication with the meter, and
c) inserting a portion of the electrochemical cell into the meter, whereby the wedge is
inserted between the portion of the first insulating substrate carrying the first electrically
conductive coating and the portion of the second insulating substrate carrying the second
electrically conductive coating that extends beyond the edge of the insulating spacer
layer, whereby an electrical connection between the first electrically conductive coating
and the lower wedge conductive surface is formed, and whereby an electrical connection
between the second electrically conductive coating and the upper wedge conductive
surface is formed.
7. The method of claim 6, the meter comprising a pivot point, wherein the wedge is capable of
rotating on the pivot point.

The present invention relates to electrochemical cells including a connector which
mates with a connection device to provide electrical connection to meter circuitry.

Documents:

694-CAL-2002-FORM-27.pdf

694-cal-2002-granted-abstract.pdf

694-cal-2002-granted-claims.pdf

694-cal-2002-granted-correspondence.pdf

694-cal-2002-granted-description (complete).pdf

694-cal-2002-granted-drawings.pdf

694-cal-2002-granted-examination report.pdf

694-cal-2002-granted-form 1.pdf

694-cal-2002-granted-form 18.pdf

694-cal-2002-granted-form 2.pdf

694-cal-2002-granted-form 3.pdf

694-cal-2002-granted-form 5.pdf

694-cal-2002-granted-gpa.pdf

694-cal-2002-granted-reply to examination report.pdf

694-cal-2002-granted-specification.pdf

694-cal-2002-granted-translated copy of priority document.pdf


Patent Number 233681
Indian Patent Application Number 694/CAL/2002
PG Journal Number 14/2009
Publication Date 03-Apr-2009
Grant Date 01-Apr-2009
Date of Filing 12-Dec-2002
Name of Patentee LIFESCAN, INC.
Applicant Address 1000 GIBRALTER DRIVE, MILPITAS, CALIFORNIA
Inventors:
# Inventor's Name Inventor's Address
1 HODGES ALASTAIR M. 15 JASMINE COURT, BLACKBURN SOUTH, VICTORIA 3130
2 CHAMBERS GARRY 81 NURIENDI ROAD, VERMONT, VICTORIA 3130
PCT International Classification Number H01M 2/00,H01M 8/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/345,743 2002-01-04 U.S.A.