Glucose sensor electrode design

Abstract

A single flex double-sided electrode useful in a continuous glucose monitoring sensor. In one example, a counter electrode is placed on the back-side of the flex and a work electrode is placed on the top-side of the sensor flex. The electrode is fabricated on physical vapor deposited metal deposited on a base substrate. Adhesion of the electrode to the base substrate is carefully controlled so that the electrode can be processed on the substrate and subsequently removed from the substrate after processing.

What is claimed is: 
     
         1 . An analyte sensor apparatus, comprising:
 a working electrode;   a counter electrode;   an insulation layer between the working electrode and the counter electrode, wherein:   the working electrode is spatially separated from the counter electrode by a distance of at least 1 micrometer,   the working electrode comprises a metal composition having an electroactive surface, and   the working electrode and the counter electrode are non-interdigitated; and   an analyte sensing layer on the working electrode, wherein the analyte sensing layer detectably alters electrical current at the working electrode in a presence of an analyte.   
     
     
         2 . The apparatus of  claim 1 , wherein the working electrode and the counter electrode are on a same side of the analyte sensor apparatus comprising a glucose sensor. 
     
     
         3 . The apparatus of  claim 1 , wherein:
 the working electrode is on a first side of the insulation layer; and   the counter electrode on a second side of the insulation layer opposite the first side.   
     
     
         4 . The apparatus of  claim 3 , further comprising:
 a sensing portion and a connection portion, the connection portion including at least one of a first contact pad or a second contact pad;   the sensing portion including the working electrode and the counter electrode; and   the sensing portion being flexible so as to allow formation of a fold between the sensing portion and the connection portion.   
     
     
         5 . The apparatus of  claim 3 , wherein the counter electrode comprises a second metal composition having an adhesion that allows peeling of the second metal composition from a direct contact with a substrate so as to remove the analyte sensor apparatus from the substrate on which the analyte sensor apparatus was fabricated. 
     
     
         6 . The apparatus of  claim 5 , further comprising:
 the second metal composition comprising a surface exposed after being peeled from the substrate;   a reference electrode on the first side of the insulation layer;   insulation between the reference electrode and the working electrode;   first contact metal electrically contacting the working electrode, the first contact metal comprising a first contact pad;   second contact metal electrically contacting the counter electrode, the second contact metal comprising a second contact pad; and wherein:   the insulation layer and the insulation comprise polyimide, and   the working electrode, the counter electrode, the insulation layer, the insulation, and the analyte sensing layer are flexible.   
     
     
         7 . The analyte sensor apparatus of  claim 5 , wherein the second metal composition comprises at least one structured layer selected from a patterned layer, a roughened layer, a non-uniform layer, a layer including voids, and a layer comprising pillars, the at least one structure layer controlling the adhesion to the substrate. 
     
     
         8 . The apparatus of  claim 7 , wherein the analyte sensor apparatus comprises a glucose sensor. 
     
     
         9 . The analyte sensor apparatus of  claim 7 , wherein the counter electrode comprises physical vapor deposited (PVD) metal. 
     
     
         10 . The analyte sensor apparatus of  claim 9 , wherein the second metal composition comprises gold. 
     
     
         11 . A method of making an analyte sensor apparatus, comprising
 depositing a working electrode and a counter electrode so that an insulation layer is between the working electrode and the counter electrode, wherein:   the working electrode is spatially separated from the counter electrode by a distance of at least 1 micrometer,   the working electrode comprises a metal composition having an electroactive surface, and   the working electrode and the counter electrode are non-interdigitated; and   depositing an analyte sensing layer on the working electrode, wherein the analyte sensing layer detectably alters electrical current at the working electrode in a presence of an analyte.   
     
     
         12 . The method of  claim 11 , further comprising depositing the working electrode and the counter electrode on a same side of the analyte sensor apparatus comprising a glucose sensor. 
     
     
         13 . The method of  claim 11 , further comprising:
 depositing the working electrode is on a first side of the insulation layer; and   depositing the counter electrode on a second side of the insulation layer opposite the first side.   
     
     
         14 . The method of  claim 12 , further comprising:
 providing a sensing portion and a connection portion, the connection portion including at least one of a first contact pad or a second contact pad; wherein:   the sensing portion includes the working electrode and the counter electrode; and   the sensing portion is flexible so as to allow formation of a fold between the sensing portion and the connection portion.   
     
     
         15 . The method of  claim 11 , further comprising depositing the counter electrode comprising a second metal composition having an adhesion that allows peeling of the second metal composition from a direct contact with a substrate so as to remove the analyte sensor apparatus from the substrate on which the analyte sensor apparatus was fabricated. 
     
     
         16 . The method of  claim 15 , further comprising peeling the analyte sensor apparatus from the substrate. 
     
     
         17 . The method of  claim 15 , wherein the second metal composition comprises a surface exposed after being peeled from the substrate, the method further comprising:
 depositing a reference electrode on the first side of the insulation layer;   providing insulation between the reference electrode and the working electrode;   depositing first contact metal electrically contacting the working electrode, the first contact metal comprising a first contact pad;   depositing second contact metal electrically contacting the counter electrode, the second contact metal comprising a second contact pad; and wherein:   the insulation layer and the insulation comprise polyimide, and   the working electrode, the counter electrode, the insulation layer, the insulation, and the analyte sensing layer are flexible.   
     
     
         18 . The method of  claim 15 , wherein the second metal composition comprises at least one structured layer selected from a patterned layer, a roughened layer, a non-uniform layer, a layer including voids, and a layer comprising pillars, the at least one structure layer controlling the adhesion to the substrate. 
     
     
         19 . The method of  claim 15 , further comprising depositing the second metal composition using physical vapor deposition. 
     
     
         20 . The method of  claim 11 , wherein the analyte sensor apparatus comprises a glucose sensor.