Sensor head for use with implantable devices

Abstract

The present invention provides a sensor head for use in an implantable device that measures the concentration of an analyte in a biological fluid which includes: a non-conductive body; a working electrode, a reference electrode and a counter electrode, wherein the electrodes pass through the non-conductive body forming an electrochemically reactive surface at one location on the body and forming an electronic connection at another location on the body, further wherein the electrochemically reactive surface of the counter electrode is greater than the surface area of the working electrode; and a multi-region membrane affixed to the nonconductive body and covering the working electrode, reference electrode and counter electrode. In addition, the present invention provides an implantable device including at least one of the sensor heads of the invention and methods of monitoring glucose levels in a host utilizing the implantable device of the invention.

What is claimed is: 
     
         1 . A sensor for use in a glucose measuring device, the sensor comprising:
 a first electrode, a second electrode, and a non-conductive body located between the first electrode and the second electrode, wherein the first electrode and the second electrode each form an electrochemically reactive surface at one end of the sensor and an electronic connection at another end of the sensor; and   a multi-region membrane covering the first electrode and the second electrode, wherein the multi-region membrane comprises an immobilized enzyme domain comprising an enzyme in at least a portion thereof, wherein the multi-region membrane comprises a glucose exclusion domain that is permeable to oxygen and interferes with glucose transport across said membrane, and wherein said glucose exclusion domain does not cover the working electrode.   
     
     
         2 . The sensor of  claim 1 , wherein the multi-region membrane further comprises an interference domain more proximal to said electrochemically reactive surfaces than said glucose exclusion domain. 
     
     
         3 . The sensor of  claim 1 , wherein the multi-region membrane further comprises a resistance domain 
     
     
         4 . The sensor of  claim 1 , wherein the multi-region membrane further comprises an immobilized enzyme domain more proximal to said electrochemically reactive surfaces than said glucose exclusion domain. 
     
     
         5 . The sensor of  claim 1 , wherein the multi-region membrane comprises a hydrogel domain adjacent to said electrochemically reactive surfaces. 
     
     
         6 . A sensor for use in a glucose measuring device, the sensor comprising:
 a first electrode, a second electrode, and a non-conductive body located between the first electrode and the second electrode, wherein the first electrode and the second electrode each form an electrochemically reactive surface at one end of the sensor and an electronic connection at another end of the sensor; and   a multi-region membrane covering the first electrode and the second electrode, wherein the multi-region membrane comprises an immobilized enzyme domain comprising an enzyme in at least a portion thereof, wherein the multi-region membrane comprises a portion positioned over only said counter electrode that reduces the consumption of oxygen above said counter electrode.   
     
     
         7 . The sensor of  claim 6 , wherein the portion comprises silicone. 
     
     
         8 . The sensor head of  claim 6 , wherein an active enzyme is positioned only over the working electrode. 
     
     
         9 . The sensor of  claim 6 , wherein an inactive enzyme is positioned only over at least one of the first electrode and the second electrode.