MX2008008468A - Electrochemical sensor system using a substrate with at least one aperature and method of making the same - Google Patents

Abstract

An electrochemical sensor system is adapted to assist in determining an analyte concentration of a fluid. The electrochemical sensor system comprises a substrate, conductive material and a hydrogel or liquid. The substrate having porosity therethrough. The conductive material includes at least one electrode. The at least one electrode is coupled to the substrate. The at least one electrode has a first surface and an opposing second surface. The hydrogel or liquid is adapted to assist in carrying the analyte of the fluid to the first and second surfaces of the at least one electrode.

Description

ELECTROCHEMICAL SENSOR SYSTEM THAT USES SUBSTRATE AT LEAST WITH AN OPENING AND METHOD OF MANUFACTURE OF THE SAME Field of the Invention The present invention relates, in general, to an electrochemical sensor system and to a method of manufacturing thereof. More specifically, the present invention relates to an electrochemical sensor system that uses a substrate having porosity therethrough and to a method of manufacturing same.

Background of the Invention The quantitative determination of analytes in bodily fluids is of great importance in the diagnosis and maintenance of certain physiological abnormalities. For example, lactate, cholesterol and bilirubin have to be monitored in certain individuals. In particular, it is important that diabetic individuals frequently check the level of glucose in their body fluids for the purpose of regulating the entry of glucose into their diets. The results of these tests can be used to determine, if any, which insulin or other medication needs to be administered. In a type of blood glucose check or verification system, sensors are used to test a blood sample.

A test sensor contains biosensing or reagent material that reacts with blood glucose. The test end of the sensor is adapted to be placed within the fluid being tested, for example, blood that has accumulated on the person's finger once the finger has been punctured. The fluid is extracted within a capillary channel that extends in the sensor from the test end to the reactive material by the action of capillarity, so that a sufficient amount of fluid will be extracted to the sensor to be tested. Then, the fluid reacts chemically with the reactive material in the sensor causing an electrical signal indicative of the glucose level in the fluid being tested. This signal is supplied to the meter by means of contact areas located next to the rear or contact end of the sensor and becomes the measured output. An existing process for the formation of an electrochemical sensor is by the deposition of a conductive metal on a substrate, and subsequently, the use of a subtractive method for the removal of the selected portions of the deposited conductive metal. Another existing process is the printing of the electrode by using a conductive ink, which is an additive process. Conductive ink could contain carbon platinum, platinum or other noble metal with a carrier that includes carbon particles. In both of these existing processes, the area of conductive metal that can be used as an electrode is limited to a single two-dimensional reception zone. Because this conductive material is expensive, it is desirable for the manufacturer to use as little conductive material as necessary while still maintaining the desired functionality. It would be desirable to have an electrochemical sensor system that reduces the amount of conductive material needed, which in turn lowers the cost, while at the same time still maintaining the desired functionality.

SUMMARY OF THE INVENTION According to one embodiment, an electrochemical sensor system is adapted to help determine the analyte concentration of a fluid. The electrochemical sensor system comprises a substrate, a conductive material and a hydrogel or liquid. The substrate has porosity through it. The conductive material includes at least one electrode. At least one electrode is coupled with the substrate. The at least one electrode has a first surface and a second opposing surface. The hydrogel or liquid is adapted to help carry the fluid analyte to the first and second surfaces of the at least an electrode According to a method, an electrochemical sensor system is formed, which is adapted to help determine the analyte concentration. A substrate that has porosity through it is provided. The conductive material is added to the substrate. The conductive material has a first side and a second side. The conductive material forms at least one electrode. A hydrogel or liquid is provided. The substrate and the at least one added electrode is brought into contact by the hydrogel, so that the analyte is adapted to make contact with the first side and the second side of the at least one electrode. According to another method, the analyte concentration of a fluid is determined. An electrochemical sensor system is also provided which includes a substrate, a conductive material and a hydrogel or liquid. The substrate has porosity through it. The conductive material is coupled with the substrate. The conductive material has a first side and a second side. The conductive material forms at least one electrode. The substrate and at least one added electrode make contact with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side of the at least one electrode. The electrochemical sensor system is placed on the skin. The analyte concentration of the fluid is determined.

Brief Description of the Figures Figure 1 is a continuous sheet of an electrochemical sensor that includes a continuous substrate with a conductive material according to one embodiment; Figure 2a is a top perspective view of an electrochemical sensor with a hydrogel according to one embodiment. Figure 2b shows an enlarged side view of an electrochemical sensor with a hydrogel of Figure 2a. Figure 2c is an enlarged cross-sectional view that is generally taken along the line 2c-2c of Figure 2a. Figure 3 is a cross-sectional view of an electrochemical sensor system with three electrodes according to one embodiment. Figure 4 is a cross-sectional view of the electrochemical sensor system with two electrodes according to one embodiment. Figure 5 is a cross-sectional view of an electrochemical sensor system with two electrodes according to another embodiment. Figure 6 is a cross-sectional view of an electrochemical sensor system with two electrodes according to a further embodiment. Figure 7 is a cross-sectional view of a Electrochemical sensor system with three electrodes according to an additional mode. Figure 8a is a top perspective view of a portion of a substrate according to one embodiment. Figure 8b is a top perspective view of the substrate of Figure 8a with an electrode added on one side according to one embodiment. Figure 8c is a top perspective view of Figure 8b with a hydrogel or fluid added according to one embodiment. Figure 8d is a side view of Figure 8c. Figure 9a is a top perspective view of a portion of a substrate according to one embodiment. Figure 9b is a top perspective view of the substrate of Figure 9a with an electrode added on both sides according to one embodiment. Figure 9c is a top perspective view of Figure 9b with a hydrogel or fluid added according to one embodiment. Figure 9d is a side view of Figure 9c. Figure 10a is a top perspective view of a portion of a substrate according to one embodiment. Figure 10b is a top perspective view of the substrate of Figure 10a with an electrode added on two sides according to another embodiment.

Figure 10c is a top perspective view of Figure 10b with a hydrogel or fluid that is being added according to another embodiment. Figure 10 is a side view of Figure 10c. Figure 11 is the electrochemical sensor system of Figure 3 which is being placed on the surface of the skin according to one embodiment. Figure 12 is an electrochemical sensor system that is used in a coulometric analysis method according to one embodiment.

Detailed Description of Illustrated Modes The present invention is directed to an electrochemical sensor system and to a process for its manufacture that reduces the amount of conductive material that is used to form at least one electrode. By using both sides of the conductive material that forms the at least one electrode, the amount of conductive material could be reduced. When the necessary amount of conductive material is reduced, the size of the electrochemical sensor system could also be decreased. By reducing the conductive material, the cost of developing the electrochemical sensor is also reduced. The electrochemical sensor system is adapted so that it is used with an instrument or meter to determine the concentration of an analyte. Desirably, the present invention is used in a transdermal analyte system due to the cost of the conductive material. In addition, in transdermal analyte systems, the ability to reduce the relatively large size of a working electrode is advantageous. The relatively large size of the working electrode is necessary in the transdermal analyte systems to provide a measurable signal at very low concentrations of analyte. These very low concentrations of analyte could be extracted as for example, of the interstitial fluid through a hydrogel or liquid. The electrochemical sensor system helps determine analyte concentrations. Analytes that could be measured include glucose, lipid profiles (eg, cholesterol, triglycerides, LDL and HDL), microalbumin, fructose, lactate or bilirubin. It is contemplated that other concentrations of analyte could be determined. The analytes could be, for example, in an intracellular and / or intercellular fluid. Intercellular fluids include ISF (interstitial fluid), a sample of blood plasma, a sample of blood serum and exudate. As used within this application, the term "concentration" refers to the concentration of analyte, activity (eg, enzymes and electrolytes), titers (for example, antibodies) or any other concentration of measurement that is used to measure the desired analyte. The electrochemical sensor system could include an enzyme selected in a suitable manner to react with the analyte or desired analytes that will be tested. For example, an enzyme that could be used to react with glucose is glucose oxidase. It is contemplated that other enzymes could be used to react with glucose such as glucose dehydrogenase. The electrochemical sensor system is adapted to help determine the analyte concentration and comprises a substrate, a conductive material and a hydrogel or liquid. The conductive material is used to form at least one electrode. The hydrogel or liquid helps carry the analyte to the conductive material. A non-limiting example of a continuous sheet of an electrochemical sensor is shown in Figure 1. Figure 1 depicts a sheet or web of an electrochemical sensor 10 that includes a continuous substrate 12 with a plurality of discrete areas of conductive material 14 that they have been added to the continuous substrate 12. The continuous substrate 12 that is depicted in Figure 1 is a gauze, a mesh or a woven material or combinations thereof. The electrochemical sensor sheet or sheet could then cut in order to provide individual electrochemical sensors. With reference to Figures 2a-c, there is shown a non-limiting example of an electrochemical sensor system 100. The electrochemical sensor system 100 includes a substrate 112, a conductive material 114 and a hydrogel or liquid 116. The conductive material 114 is coupled with the substrate 112. More specifically, as shown in Fig. 2b, the conductive material 114 is bonded to the substrate 112. The hydrogel 116, as seen in Figure 2b, is located above and by below the conductive material 114 and the substrate 112. The substrate 112 to be used in the electrochemical sensor system 100 is porous and includes a sufficient strength to support the conductive material 114. The substrate could comprise a mesh, gauze, woven material or combinations thereof. It is contemplated that the substrate could use other shapes that are sufficiently porous so as to allow the hydrogel or liquid to move therethrough and contact both sides 114a, 114b of the conductive material 114. For example, a solid material does not porous could have at least one and more desirably, a plurality of openings formed therein which allow both sides of the conductive material to be accessible to the hydrogel or liquid. By having accessible both sides of the conductive material to the hydrogel or liquid, the time required for the analyte to reach the conductive material is reduced. In one embodiment, the substrate 112 forms a plurality of openings 126 therein (see Figure 2a). The openings could be of various sizes and shapes, although they are formed to allow the hydrogel or fluid to make contact with the conductive material 114 on both sides 114a, 114b. Desirably, the openings are of a size and dimension corresponding to the analyte that will pass through the openings 126. This would include the desirable amount and speed of the analyte flow. By using both sides 114a, 114b of the conductive material 114, the total receiving zone and the amount of conductive material that is required to form at least one electrode is reduced. In this way, by allowing the hydrogel or liquid to make contact on both sides of the conductive material, the electrodes could be of a smaller size, which leads to the development of a smaller electrochemical sensor. However, it is contemplated that the substrate could accurately form an opening therethrough that allows the hydrogel or fluid to make contact on both surfaces of the conductive material. The substrate could be manufactured from a variety of materials. For example, the substrate could be formed from a polymeric material. Non-limiting examples of polymeric materials that could be used to form the substrate include polyethylenes, polyplene polyethylene terephthalates (PET) polyethers, polycarbonates or combinations thereof. The polymeric material could be previously formed with openings or the polymeric material could have openings formed therethrough in a subsequent processing. It is contemplated that other polymeric materials could be used to form the substrate such as a porous ceramic and cellulose material. If a non-porous solid material was used, then the material could be porous by pre-forming openings therethrough. Alternatively, the ceramic material could be formed in a way that configures openings therethrough in further processing. The substrate could be formed of a metallic material, although this is often undesirable because this substrate would probably need to include a dielectric insulation layer. The substrate could also be used in order to create an electric field pattern that prevents or prevents interference materials from reaching the analysis area. By reducing the interference materials, the determination of the analyte concentration could be improved. In this mode, the substrate creates a positively charged surface or negative that helps prevent or prevent interference materials from reaching the area of analysis. In the case of determining the glucose concentration of the analyte, this field would have little or no effect with glucose, because the glucose does not have a charge. It would be highly desirable that the electric field pattern had little or no effect on the analyte concentration that is being determined. These electric field patterns could be applied to the substrate (eg, the lower portion of the substrate closest to the skin) which prevents or prevents the interference compounds from passing through based on the charging prties. In this mode, the analysis usually happens on the opposite surface of the substrate (for example, the upper portion of the substrate that is farthest from the skin). The electric field patterns in one modality could be located in the openings formed in the substrate. The electric field patterns could be applied to the substrate, for example, through the printing or coating methods. In one embodiment, exactly one side of the substrate is printed or coated with bonding materials that would couple the interference materials. It is contemplated that both sides of the substrate could include these bonding materials. In another modality, the substrate could include a enzyme that is used to help determine the analyte concentration. In this embodiment, the enzyme could be coated on one side of the substrate, while the conductive material is located on the opposite side. In this modality, the intermediate part in the analysis process would be produced in close proximity to the place where the next stage of the analysis process happens. This increases the efficiency of the conversion and therefore increases the signal observed in the sensor. For example, if the analyte to be determined is glucose using the enzyme glucose oxidase, then the peroxide would form on the surface of the substrate with the glucose oxidase coating. It is desirable that the coating cover the substrate in such a way that the substrate remains porous. For example, if the substrate were a gauze or mesh, the coating would be added in order to leave the plurality of openings formed in the gauze or mesh partially open to help the hydrogel or fluid to be in contact with both sides of the conductive material. It is also contemplated that the substrate could include a mediator that is an electron acceptor and that helps generate a current that corresponds to the analyte concentration. It is also contemplated that other additives could be added to the substrate to help facilitate the determination of the selected analyte.

The conductive material 114 is added to the substrate 112 and forms at least one electrode. Typically, the conductive material 114 forms a plurality of electrodes. For example, in Figure 2c, the conductive material 114 forms a plurality of electrodes, which include a working electrode 118 and a counter electrode 120. The working electrode 118 and the counter electrode 120 create an electrochemical current that can flow when these electrodes they are connected in electrical form and that a potential is created between them. The plurality of electrodes could include three or more electrodes such as a counter electrode, a working electrode and a reference electrode. An example of an electrochemical sensor system including three electrodes is shown in Figure 3. Specifically, the electrochemical sensor system 200 of Figure 3 includes the substrate 112, the conductive material 214 and a hydrogel 216. The conductive material 214 includes a working electrode 218, a counter electrode 220 and a reference electrode 222. It is contemplated that more or fewer electrodes may be formed using the conductive material. The electrodes created through the enzymatic reaction are moved through the working electrode to a meter or instrument that measures the magnitude of the current flow. The counter electrode provides a potential fixed against which the working electrode is controlled. The counter electrode could also be used to complete the electrical circuit. The conductive material could be added onto the surface of the substrate in one embodiment. It is contemplated that the aggregate conductive material, if printed for example, could be added onto a surface of the substrate and also penetrate the surface thereof. Examples of the conductive material being added onto the surface of a substrate are shown in Figures 2c, 3 and 4. In Figure 4, an electrochemical sensor 300 is shown which includes the substrate 112, a conductive material 314 and a hydrogel 316. The conductive material 314 includes a working electrode 318 and a counter electrode 320 in which the working and counter electrode electrodes 318, 320 are located on opposite sides of the substrate 112. In another embodiment, the conductive material could be located, at least partially, within the substrate. With reference to Figure 5, an electrochemical sensor 400 is shown which includes the substrate 112, a conductive material 414 and a hydrogel 416. The conductive material 414 is located, at least partially, within the substrate 112. More specifically, the conductive material 114, which includes a working electrode 418 and a counter electrode 420, is located within the substrate 112.

It is contemplated that the conductive material could be located both on the substrate and within it. For example, in Figure 6, an electrochemical sensor system 500 is shown including the substrate 112, a conductive material 514 and a hydrogel 516. The conductive material 514 includes a working electrode 518 and a counter electrode 520. The working electrode 518 is located within the substrate 112 and the counter electrode 520 is located on the substrate 112. In another embodiment, the electrochemical sensor system 600 of Figure 7 includes the substrate 112, a conductive material 614 and a hydrogel 616. The conductive material 614 it comprises a working electrode 618 and a counter electrode 620 and a reference electrode 622. The working and reference electrodes 618, 622 are located within the substrate 112 and the counter electrode 620 is located on the substrate 112. The conductive material could be a material metallic or other conductive material such as platinum carbon. Non-limiting examples of metallic conductive materials include copper, nickel, gold, platinum, palladium, rhodium or combinations thereof. The thickness of the metallic conductive material is, generally, around 10 to 10,000 Angstroms. The thickness of the metallic conductive material is most commonly approximately 100 to 1000 Angstroms. The thickness of the conductive material could be larger than the thickness of the substrate. For example, if the conductive material were platinum carbon, then the thickness of this conductive material would normally be larger than the thickness of the substrate. It is also contemplated that the thickness of the conductive material could be less than the thickness of the substrate. For example, if a platinum coating were added to the substrate, then, typically, the thickness of this coating would be less than the thickness of the substrate. The size and shape of the conductive material is shown in Figure 2a which includes a generally circular portion 114c and an extension portion 114d extending therefrom. The size and shape of the conductive material may vary from those shown in Figures 1, 2a. The size and shape of the conductive material are selected to facilitate the determination of analyte concentration, as well as in order to reduce the cost associated with the manufacture thereof. The size and shape of the conductive material could also be selected due to other reasons. For example, if a reservoir were used to supply the hydrogel or liquid, then the placement of the conductive material could be optimized in order to provide the desired porosity that take the hydrogel or liquid from the reservoir to the skin's contact location. A deposit could be used if the characteristics of the hydrogel had the tendency to change with respect to a test period, which would normally include the percentage of solvent of the hydrogel that is being reduced with respect to time. In one embodiment, a hydrogel is used to aid in the hydration of the skin and to carry the analyte of interest to at least one electrode formed by the conductive material. The content of the solvent (e.g., water) in the hydrogel may vary. To increase the mechanical strength of the hydrogel 116, the hydrogel 116 is supported by the substrate 112 with the conductive material 114. In this way, the need for an additional substrate material is eliminated. A hydrogel composition is defined herein that includes a cross-linked polymer gel. Generally, the hydrogel composition comprises at least one monomer and a solvent. Normally, the solvent is substantially biocompatible with the skin. Non-limiting examples of solvents that could be used in the hydrogel composition include water and a mixture of water. The amount of solvent in the hydrogel is generally 10 to 95 percent by weight and could vary depending on the amount of the monomer, the cross link and / or the desired composition of the gel. The amount of hydrogel that is selected is based on the need to provide a hydrated skin and that the hydrogel remains in intimate contact with the skin. A disadvantage of the use of a large amount of hydrogel in the electrochemical sensor system is the potential impact on the delay time for the analyte to reach at least one electrode and, thus, the possible impact of the analysis time. By having an electrochemical sensor system in which the hydrogel is able to make contact on both sides with at least one electrode, the impact effect of the analyte delay times to reach the electrodes is reduced. It is advantageous to have a hydrogel with the ability to make contact on both sides of a plurality of electrodes. By having an electrochemical sensor system that is capable of making contact on both sides of at least one electrode and desirably in a plurality of electrodes, the present invention has the ability to utilize a larger amount of water in the hydrogel. Also, it is contemplated that a liquid could be used to help hydrate the skin and bring the analyte of interest to at least one electrode formed by the conductive material. It is contemplated that the liquid or hydrogel could be placed in a matrix of material. In In this mode, the material matrix must allow the movement of the liquid or hydrogel at least towards an electrode. It is also contemplated that the mediator could be located in the hydrogel or liquid. To maximize efficiency, the mediator's distribution could be structured. It is also contemplated that other components could be located within the hydrogel or liquid. With reference to Figures 8-10, a single electrode is shown in different embodiments on a portion of the substrate. First, with reference to Figures 8a-8d, a substrate 650 with a plurality of apertures 652 formed therein is shown. As shown in Figure 8b, the substrate 650 has a single electrode 656 which is located on the surface 650a of the substrate 650. A hydrogel or liquid 658 is added onto the substrate 650 and the electrode 656 as shown in Figures 8c and 8d. The hydrogel or liquid 658 extends to and through the plurality of openings 652. In this embodiment, the electrode 656 does not extend toward the plurality of openings 652. However, it is contemplated that the electrode could extend toward the plurality of openings. With reference to Figures 9a-9d, a substrate 650 with a plurality of openings 652 formed therein is shown. As shown in Figure 9b, the substrate 650 it has a single electrode 666 which is located on the surfaces 650a, 650b of the substrate 650. More specifically, the electrode 666 is located on the opposite surfaces 650a, 650b of the substrate 650 and extends through the plurality of openings 652. Substantially, the electrode 666 fills the plurality of openings 652. It is contemplated that the electrode could partially fill the plurality of openings so that an electrical connection is still established between them. A hydrogel or liquid 668 is added onto the substrate and electrode 666 as shown in Figures 9c and 9d. It is contemplated that the hydrogel or liquid could extend into and through the plurality of openings if the electrode 666 does not substantially fill the plurality of openings 652. Referring to FIGS. 10a-10d, a substrate 650 with a plurality of openings 652 formed therein. As shown in Figure 10b, the substrate 650 has a single electrode 676 that includes a first electrode section 676a and a second electrode section 676b. The first electrode section 676a is located on the surface 650a, while the second electrode section 676b is located on the surface 650b of the substrate 650. In this way, the first and second electrode sections 676a, 676b do not extend through of the plurality of openings 652. It is contemplated that the electrode sections could be extended, in part, towards the plurality of openings. A hydrogel or liquid 678 is added onto the substrate and electrode sections 676a, 676b as shown in Figures 10c and 10d. The hydrogel or liquid 680 extends to and through the plurality of openings 652. In the embodiments shown in Figures 8-10, only a single electrode (e.g., the working electrode) has been depicted. It is contemplated that the working electrode, the counter electrode or any other electrode could be on both sides of the substrate, only on one side of the substrate or on opposite sides of the substrate. According to one method, an electrochemical sensor system is formed, which is adapted to help determine an analyte concentration. A substrate with a porosity therethrough (eg, substrate 112) in one embodiment comprises a mesh, gauze, woven material or combinations thereof. As discussed above, the substrate 112 forms openings therein. The conductive material (e.g. conductive material 114) is added to the substrate. The conductive material has a first side and a second side and forms at least one electrode. A hydrogel (e.g., hydrogel 116) or liquid is provided. The substrate with the plurality of The electrode makes contact with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side of at least one electrode. The conductive material as shown for example, in Figure 3, is placed in the general center of the hydrogel. The conductive material could be added to the substrate through different techniques. In one method, the conductive material is added to the substrate by sputtering. The ion bombardment process could deposit metals such as platinum, copper, nickel, gold, palladium, rhodium and combinations thereof. It is contemplated that other conductive materials could be subjected to the sputtering process on the substrate. The sputtering process places the conductive material on at least one surface of the substrate and the conductive material could penetrate the substrate to some extent. It is contemplated that the sputtering process could be used to place the conductive material on both sides of the substrate. In another method, the conductive material is added to the substrate by the printing process. The printing could be done using platinum or platinum carbon inks. It is contemplated that other conductive materials could be printed on the substrate. In a common printing process, the conductive material is placed on at least one surface and the material Conductive could penetrate the substrate to some extent. It is contemplated that the printing process could add the conductive material on both sides of the substrate. It is contemplated that other methods could be used to add the conductive material to the substrate. For example, the conductive material could be added to the substrate using the electrodeposition or powder coating. In one embodiment, all electrodes are added to the substrate. It is contemplated that unless all the electrodes are added to the substrate. For example, one electrode could be added to the substrate while another electrode is located next to the analysis area. The present invention could be used in a transdermal process in which the analyte is monitored continuously. As shown in Figure 11, the electrochemical system 200 of Figure 3 is shown in a transdermal application. Specifically, the electrochemical system 200 is shown to be positioned above a layer of stratum corneum 252 of the epidermis 250 in Figure 11. The layer of stratum corneum 250 has a plurality of channels 252a-d formed therein. . The channels could be of different sizes and depths depending on the analyte being tested and the location of the analyte in the skin.

The plurality of channels 252a could be formed through various methods such as the laser-initiated opening, a lancet, or a pressure member adapted to apply pressure and stretch the skin in preparation for the formation of a tear in the skin. It is contemplated that other methods could be used such as the use of foams or gels, tape separation or various methods of skin abrasion. The analyte of interest could be located in the epidermis 250 or in the dermis layer 254. For example, an analyte (eg, glucose) is located in the dermis layer. Glucose, for example, diffuses through the fluid pathways that are established in the plurality of channels 252 formed in the layer of stratum corneum 250. The hydrogel, with a generally high water content, maintains a fluid channel for diffusion of the analyte of interest. The electrochemical sensor system could also be used to continuously monitor the analytes in ISF. These analytes could be located on the skin. Normally, the analytes are located in the transdermal region (the epidermis, dermis or subcutaneous tissue) of the skin. The analytes are brought to the surface of the skin using different channels. Then, the examination is performed on the surface of the skin using various analytical techniques.

It is contemplated that an electrochemical sensor system of the present invention could utilize a coulometric analysis method. The coulometric analysis procedure would similarly increase the sensitivity of the assay in which a greater signal would be generated. An example of an electrochemical sensor system using a coulometric analysis method is shown in connection with Figure 12. The electrochemical sensor system 700 of Figure 12 includes a substrate 712 with a conductive material 714, a hydrogel 716 and an electrode 718. The electrochemical sensor system 700 is placed on the skin 740. The conductive material 714 includes a counter electrode 720. In this embodiment, the working electrode 718 is printed on the reinforcing material 730. The reinforcing material 730 could be made of a reinforcing polymer material. The coulometric analysis is conducted between the counter electrode 720 on the substrate 712 and the working electrode 718. The coulometric analysis is based on the conversion of the entire analyte into a defined volume. The defined area of Figure 12 is the area 732 between the substrate 712 / counter electrode 720 and the working electrode 718. This area 732 is predominantly occupied by the hydrogel 716, although it also contains the diffuse analyte (e.g., glucose) or the glucose conversion product. He Analysis is based on the integration of the generated current with respect to a period of time. The side of the substrate that is located outside the skin could also form the lower part of the chamber containing a liquid such as water, which forms a reservoir for the hydrogel that is below the gauze and in contact with the skin. This would help hydrate the hydrogel for longer periods of time. The location of the sensors on the substrate provides a significant drift of design freedom and the materials that can be used on the opposite surface of the substrate. A thick hydrous hydrogel could largely be used to provide a reservoir for the hydrogel in contact with the skin. The increase in thickness would have little or no impact on the delay times. MODE A An electrochemical sensor system adapted to assist in determining the analyte concentration of a fluid, the electrochemical sensor system comprising: a substrate having porosity therethrough; a conductive material that includes at least one electrode, at least one electrode is coupled to the substrate, at least one electrode has a first surface and a second opposing surface; and a hydrogel or liquid is adapted to help bringing the analyte of the fluid to the first and second surfaces of the at least one electrode. MODE B The system of mode A, where the substrate is a mesh, gauze, woven material or solid material with openings. MODALITY C The system of mode B, where the substrate is a mesh. MODALITY D The system of mode B, where the substrate is a gauze. MODALITY E The system of mode B, where the substrate has an electric field pattern. MODE F The system of mode B, wherein the substrate comprises polymeric material, cellulose material or porous ceramic. MODE G The system of mode A, wherein the porosity of the substrate includes a plurality of openings formed therethrough. MODE H The system of mode A, where at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode. MODE I The system of mode A, where at least one electrode is located on a surface of the substrate. MODE J The system of mode A, wherein a portion of at least one electrode is located within the substrate. MODALITY K The system of mode A, where the conductive material is metallic. MODE L The system of mode A, wherein at least one electrode has a first section and a second section, the first section has the first surface and the second section has the second opposite surface. MODE M The system of mode A, wherein the porosity of the substrate includes at least one opening that is formed therethrough, the conductive material substantially fills at least one opening. MODE N The system of mode A, where the electrochemical sensor system uses a hydrogel.

MODALITY OR The system of the N mode, where the hydrogel is a cross-linked polymer. MODALITY P The system of mode A, where the electrochemical sensor system uses a liquid. MODALITY Q The system of mode A, where the hydrogel or liquid is in a matrix of material. MODALITY R The system of mode A, where the electrochemical sensor system is a coulometric system. MODALITY S The system of mode A, where the electrochemical sensor system is an amperometric system. MODALITY T The system of mode A, where the electrochemical sensor system also includes an enzyme, the enzyme is glucose oxidase or glucose dehydrogenase. PROCESS U A method of forming an electrochemical sensor system that is adapted to help determine an analyte concentration, the method comprises the steps of: providing a substrate having porosity to through it; adding a conductive material to the substrate, the conductive material has a first side and a second side, the conductive material forms at least one electrode; provide a hydrogel or liquid; and contacting the substrate and at least one electrode added with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side on at least one electrode. PROCESS V The process method U, where the conductive material is placed in the general center of the hydrogel or the liquid. PROCESS W The process method U, where the conductive material is added to the substrate by sputtering. PROCESS X The process method U, where the conductive material is added to the substrate by printing. PROCESS AND The process method U, where the analyte is glucose. PROCESS Z The process method U, where the substrate is a mesh, gauze, woven material or solid material with openings. PROCESS AA The process method Z, where the substrate is a gauze. PROCESS BB The process method U, wherein the substrate comprises polymeric material, cellulose material or porous ceramic. PROCESS CC The process method U, wherein the porosity of the substrate includes a plurality of openings formed therethrough. DD PROCESS The process method U, wherein at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode. PROCESS EE The process method U, wherein at least one electrode is located on a surface of the substrate. FF PROCESS The process method U, wherein a portion of at least one electrode is located within the substrate. PROCESS GG The process method U, where at least one of the The electrode has a first section and a second section, the first section has the first surface and the second section has the second opposite surface. PROCESS HH The process method U, wherein the porosity of the substrate includes at least one opening that is formed therethrough, the conductive material substantially fills at least one opening. PROCESS II The process method U, where the electrochemical sensor system uses a hydrogel. PROCESS JJ The process method U, where the hydrogel is a cross-linked polymer. KK PROCESS The process method U, where the electrochemical sensor system uses a liquid. LL PROCESS The process method U, where the electrochemical system is a coulombimetric system. MM PROCESS The process method U, where the electrochemical system is an amperometric system. PROCESS NN A method of determining a concentration of analyte of a fluid, the method comprises the steps of: providing an electrochemical sensor system that includes a substrate, a conductive material, a hydrogel or liquid, the substrate has porosity therethrough, the conductive material is coupled to the substrate, the conductive material has a first side and a second side, the conductive material forms at least one electrode, the substrate and at least one added electrode are brought into contact with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side at least one electrode; place the electrochemical sensor system on the skin; and determine the analyte concentration of the fluid. PROCESS 00 The NN process method, where the analyte is glucose. PROCESS PP The process method NN, where the substrate is a mesh, gauze, woven material or solid material with openings. QQ PROCESS The NN process method, wherein the porosity of the substrate includes a plurality of openings formed therethrough.

PROCESS RR The process method NN, wherein at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode. SS PROCESS The NN process method, where the electrochemical sensor system uses a hydrogel. TT PROCESS The NN process method, where the electrochemical sensor system uses a liquid. PROCESS UU The process method NN, where the fluid is an intercellular fluid. PROCESS UU The process method NN, where the fluid is an interstitial fluid. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes could be made thereto without departing from the spirit and scope of the present invention. Each of these modalities and the obvious variations thereof are contemplated to fall within the spirit and scope of the invention as defined by the appended claims.

Claims (48)

1. CLAIMS 1. An electrochemical sensor system adapted to assist in determining the analyte concentration of a fluid, characterized in that it comprises: a substrate having porosity therethrough; a conductive material that includes at least one electrode, the at least one electrode is coupled to the substrate, the at least one electrode has a first surface and a second opposing surface; and a hydrogel or liquid is adapted to help bring the analyte of the fluid to the first and second surfaces of the at least one electrode.
2. 2. The system in accordance with the claim 1, characterized in that the substrate is a mesh, gauze, woven material or solid material with openings.
3. 3. The system in accordance with the claim 2, characterized in that the substrate is a mesh.
4. 4. The system according to claim 2, characterized in that the substrate is a gauze.
5. 5. The system according to claim 2, characterized in that the substrate has an electric field pattern.
6. The system according to claim 2, characterized in that the substrate comprises polymeric material, cellulose material or porous ceramic.
7. 7. The system in accordance with the claim 1, characterized in that the porosity of the substrate includes a plurality of openings formed therethrough.
8. The system according to claim 1, characterized in that at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode.
9. The system according to claim 1, characterized in that the at least one electrode is located on a surface of the substrate.
10. The system according to claim 1, characterized in that a portion of the at least one electrode is located within the substrate.
11. 11. The system according to claim 1, characterized in that the conductive material is metallic.
12. The system according to claim 1, characterized in that at least one electrode has a first section and a second section, the first section has the first surface and the second section has the second opposite surface.
13. The system according to claim 1, characterized in that the porosity of the substrate includes at least one opening that is formed therethrough, the conductive material substantially fills at least one opening.
14. 14. The system according to claim 1, characterized in that the electrochemical sensor system uses a hydrogel.
15. 15. The system according to claim 14, characterized in that the hydrogel is a cross-linked polymer.
16. 16. The system according to claim 1, characterized in that the electrochemical sensor system uses a liquid.
17. 17. The system in accordance with the claim 1, characterized in that the hydrogel or liquid is in a matrix of material.
18. 18. The system according to claim 1, characterized in that the electrochemical sensor system is a coulmbymmetric system.
19. 19. The system according to claim 1, characterized in that the electrochemical sensor system is an amperometric system.
20. 20. The system according to claim 1, characterized in that the electrochemical sensor system also includes an enzyme, the enzyme is glucose oxidase or glucose dehydrogenase.
21. 21. A method of forming an electrochemical sensor system that is adapted to assist in determining an analyte concentration, characterized in that it comprises stages of: providing a substrate having porosity therethrough; adding a conductive material to the substrate, the conductive material has a first side and a second side, the conductive material forms at least one electrode; provide a hydrogel or liquid; and contacting the substrate and the at least one electrode added with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side of the at least one electrode.
22. 22. The method of compliance with the claim 21, characterized in that the conductive material is placed in the general center of the hydrogel or the liquid.
23. 23. The method according to claim 21, characterized in that the conductive material is added to the substrate by sputtering.
24. 24. The method according to claim 21, characterized in that the conductive material is added to the substrate by printing.
25. 25. The method according to claim 21, characterized in that the analyte is glucose.
26. 26. The method according to claim 21, characterized in that the substrate is a mesh, gauze, woven material or solid material with openings.
27. 27. The method according to claim 26, characterized in that the substrate is a gauze.
28. 28. The method according to claim 21, characterized in that the substrate comprises polymeric material, cellulose material or porous ceramic.
29. 29. The method according to claim 21, characterized in that the porosity of the substrate includes a plurality of openings formed therethrough.
30. 30. The method according to claim 21, characterized in that at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode.
31. 31. The method according to claim 21, characterized in that at least one electrode is located on a surface of the substrate.
32. 32. The method of compliance with the claim 21, characterized in that a portion of the at least one electrode is located within the substrate.
33. 33. The method according to claim 21, characterized in that the at least one of the electrode has a first section and a second section, the first section has the first surface and the second section has the second opposite surface.
34. 34. The method according to claim 21, characterized in that the porosity of the substrate includes at least one opening that is formed therethrough, the conductive material substantially fills at least one opening.
35. 35. The method according to claim 21, characterized in that the electrochemical sensor system uses a hydrogel.
36. 36. The method according to claim 35, characterized in that the hydrogel is a cross-linked polymer.
37. 37. The method according to claim 21, characterized in that the electrochemical sensor system uses a liquid.
38. 38. The method according to claim 21, characterized in that the electrochemical system is a coulometric system.
39. 39. The method of compliance with the claim 21, characterized in that the electrochemical system is an amperometric system.
40. 40. A method for determining an analyte concentration of a fluid, characterized in that it comprises the steps of: providing an electrochemical sensor system that includes a substrate, a conductive material, a hydrogel or liquid, the substrate has porosity therethrough , the conductive material is coupled with the substrate, the conductive material has a first side and a second side, the conductive material forms at least one electrode, the substrate and the at least one added electrode are brought into contact with the hydrogel, so that the analyte is adapted to make contact with the first side and the second side of the at least one electrode; place the electrochemical sensor system on the skin; and determine the analyte concentration of the fluid.
41. 41. The method according to claim 40, characterized in that the analyte is glucose.
42. 42. The method according to claim 40, characterized in that the substrate is a mesh, gauze, woven material or solid material with openings.
43. 43. The method according to claim 40, characterized in that the porosity of the substrate includes a plurality of openings formed therethrough.
44. 44. The method of compliance with the claim 40, characterized in that at least one of the plurality of electrodes is a plurality of electrodes, the plurality of electrodes includes a working electrode and a counter electrode.
45. 45. The method according to the claim 40, characterized in that the electrochemical sensor system uses a hydrogel.
46. 46. The method according to claim 40, characterized in that the electrochemical sensor system uses a liquid.
47. 47. The method according to claim, characterized in that the fluid is an intercellular fluid.
48. 48. The method according to claim, characterized in that the fluid is an interstitial fluid.