Methods and materials for controlling the electrochemistry of analyte sensors

Abstract

Embodiments of the invention provide electrochemical analyte sensors having elements designed to modulate their electrochemical reactions as well as methods for making and using such sensors.

1 . A method of modulating electrochemical reactions within an implantable analyte sensor, the method comprising performing electrochemical reactions within an implantable analyte sensor comprising:
 a working electrode having a reactive surface area, wherein during analyte sensing, the working electrode generates electrons that reduce a plurality of composition species in the electrochemical reaction including oxygen (O 2 ); and   a counter electrode having a reactive surface area, wherein the size of the reactive surface area of the counter electrode is selected so as to control the reduction of the plurality of composition species in the electrochemical reaction so that oxygen (O 2 ) is the predominant composition species reduced by the electrons generated at the working electrode;   so that electrochemical reactions within the implantable analyte sensor are modulated.   
     
     
         2 . The method of  claim 1 , wherein the surface area of the counter electrode is 1.5, 2, 2.5 or 3 times the size of the working electrode. 
     
     
         3 . The method of  claim 1 , wherein the implantable analyte sensor comprises
 an analyte sensing layer disposed on the working electrode, wherein the analyte sensing layer detectably alters the electrical current at the working electrode in the presence of an analyte;   an optional protein layer disposed on the analyte sensing layer;   an adhesion promoting layer disposed on the analyte sensing layer or the optional protein layer, wherein the adhesion promoting layer promotes the adhesion between the analyte sensing layer and an analyte modulating layer disposed on the analyte sensing layer; and   an analyte modulating layer disposed on the analyte sensing layer, wherein the analyte modulating layer modulates the diffusion of the analyte therethrough; and   an optional cover layer disposed on at least a portion of the analyte modulating layer, wherein the cover layer further includes an aperture over at least a portion of the analyte modulating layer.   
     
     
         4 . The method of  claim 1 , wherein the working electrode and the counter electrode comprise a micro-porous matrix. 
     
     
         5 . The method of  claim 4 , wherein the micro-porous matrix has a surface area that is at least 2, 4, 6, 8, 10, 12, 14, 16 or 18 times the surface area of a non-porous matrix of same dimensions. 
     
     
         6 . The method of  claim 2 , wherein the analyte sensing layer is a protein. 
     
     
         7 . The method of  claim 6 , wherein the protein is glucose oxidase, glucose dehydrogenase, lactate oxidase, hexokinase or lactate dehydrogenase. 
     
     
         8 . The method of  claim 1 , wherein hydrogen peroxide is oxidized at the working electrode. 
     
     
         9 . The method of  claim 2 , wherein the implantable analyte sensor further comprises an interference rejection layer disposed between the surface of the working electrode and the analyte sensing layer. 
     
     
         10 . An implantable electrochemical analyte sensor comprising:
 a working electrode having a reactive surface area, wherein during analyte sensing, the working electrode generates electrons that reduce a plurality of composition species in the electrochemical reaction including oxygen (O 2 ); and   a counter electrode having a reactive surface area, wherein the size of the reactive surface area of the counter electrode is selected so as to control the reduction of the plurality of composition species in the electrochemical reaction so that oxygen (O 2 ) is the predominant composition species reduced by the electrons generated at the working electrode;   an analyte sensing layer disposed on the working electrode, wherein the analyte sensing layer detectably alters the electrical current at the working electrode in the presence of an analyte;   an adhesion promoting layer disposed on the analyte sensing layer or the protein layer, wherein the adhesion promoting layer promotes the adhesion between the analyte sensing layer and an analyte modulating layer disposed on the analyte sensing layer; and   an analyte modulating layer disposed on the analyte sensing layer, wherein the analyte modulating layer modulates the diffusion of the analyte therethrough; and   a cover layer disposed on at least a portion of the analyte modulating layer, wherein the cover layer further includes an aperture over at least a portion of the analyte modulating layer.