Continuous glucose monitoring device

Abstract

A wire-based three-pole sensor for subcutaneous insertion includes a working electrode including a first split wire having a first flat surface, and a support sheet on the first flat surface. The first flat surface is created from a full wire having a circular cross-section with a portion removed. A reference electrode includes a second split wire having a second flat surface. The second flat surface is defined by a second chord across a circular cross-section of the second split wire. A counter electrode includes a third split wire having a third flat surface. The third flat surface is defined by a third chord across a circular cross-section of the third split wire. The second and third flat surfaces face each other. A cross-sectional diameter of the first split wire, the second split wire, and the third split wire coupled together is less than an inner diameter of an insertion needle.

What is claimed is: 
     
         1 . A wire-based three-pole electrochemical sensor for subcutaneous insertion comprising:
 a working electrode comprising a first split wire having a first flat surface along a length of the first split wire, and a support sheet on the first flat surface, the first flat surface created from a first full wire having a circular cross-section with a portion removed;   a reference electrode comprising a second split wire having a second flat surface along a length of the second split wire, the second flat surface created from a second full wire defined by a second chord across a circular cross-section of the second split wire; and   a counter electrode comprising a third split wire having a third flat surface along a length of the third split wire, the third flat surface created from a third full wire defined by a third chord across a circular cross-section of the third split wire;   wherein the second flat surface and the third flat surface face toward each other;   wherein a cross-sectional diameter of the first split wire, the second split wire, and the third split wire coupled together is less than an inner diameter of an insertion needle.   
     
     
         2 . The sensor of  claim 1 , wherein the support sheet comprises carbon. 
     
     
         3 . The sensor of  claim 1 , wherein the support sheet comprises graphene, pyrrole or polyaniline. 
     
     
         4 . The sensor of  claim 1 , wherein the support sheet is electrically conductive and electrically coupled to the flat surface of the first split wire. 
     
     
         5 . The sensor of  claim 1 , further comprising a sensing chemistry deposited on the support sheet. 
     
     
         6 . The sensor of  claim 1 , further comprising a polymer layer over the support sheet. 
     
     
         7 . The sensor of  claim 1 , wherein:
 the circular cross-section with the portion removed of the first split wire of the working electrode forms a semicircular cross-section;   the second chord across the circular cross-section of the second split wire of the reference electrode forms a semicircular cross-section; and   the third chord across the circular cross-section of the third split wire of the counter electrode forms a semicircular cross-section.   
     
     
         8 . The sensor of  claim 1 , wherein:
 the circular cross-section with the portion removed of the first split wire of the working electrode forms a rectangular cross-section;   the second chord across the circular cross-section of the second split wire of the reference electrode forms a semicircular cross-section; and   the third chord across the circular cross-section of the third split wire of the counter electrode forms a semicircular cross-section.   
     
     
         9 . The sensor of  claim 1 , wherein the second split wire and the third split wire each have a surface area of 82% of the respective second full wire or third full wire having the same diameter. 
     
     
         10 . The sensor of  claim 1 , wherein:
 a cross-sectional area of the second split wire of the reference electrode is 30% to 70% of the cross-section of the second full wire; and   a cross-sectional area of the third split wire of the counter electrode is 30% to 70% of the cross-section of the third full wire.   
     
     
         11 . A wire-based three-pole electrochemical sensor for subcutaneous insertion comprising:
 a working electrode comprising a first split wire having a first flat surface along a length of the first split wire, and a support sheet on the first flat surface comprising carbon, and a sensing chemistry deposited on the support sheet, the first flat surface created from a first full wire having a circular cross-section with a portion removed;   a reference electrode comprising a second split wire having a second flat surface along a length of the second split wire, the second flat surface created from a second full wire defined by a second chord across a circular cross-section of the second split wire; and   a counter electrode comprising a third split wire having a third flat surface along a length of the third split wire, the third flat surface created from a third full wire defined by a third chord across a circular cross-section of the third split wire;   wherein the second flat surface and the third flat surface face toward each other;   wherein a cross-sectional diameter of the first split wire, the second split wire, and the third split wire coupled together is less than an inner diameter of an insertion needle.   
     
     
         12 . The sensor of  claim 11 , wherein the support sheet further comprises graphene, pyrrole or polyaniline. 
     
     
         13 . The sensor of  claim 11 , wherein the support sheet is electrically conductive and electrically coupled to the flat surface of the first split wire. 
     
     
         14 . The sensor of  claim 11 , further comprising a polymer layer over the support sheet. 
     
     
         15 . The sensor of  claim 11 , wherein:
 the circular cross-section with the portion removed of the first split wire of the working electrode forms a semicircular cross-section;   the second chord across the circular cross-section of the second split wire of the reference electrode forms a semicircular cross-section; and the third chord across the circular cross-section of the third split wire of the counter electrode forms a semicircular cross-section.   
     
     
         16 . The sensor of  claim 11 , wherein:
 the circular cross-section with the portion removed of the first split wire of the working electrode forms a rectangular cross-section;   the second chord across the circular cross-section of the second split wire of the reference electrode forms a semicircular cross-section; and   the third chord across the circular cross-section of the third split wire of the counter electrode forms a semicircular cross-section.   
     
     
         17 . The sensor of  claim 11 , wherein the second split wire and the third split wire each have a surface area of 82% of the respective second full wire or third full wire having the same diameter. 
     
     
         18 . The sensor of  claim 11 , wherein:
 a cross-sectional area of the second split wire of the reference electrode is 30% to 70% of the cross-section of the second full wire; and   a cross-sectional area of the third split wire of the counter electrode is 30% to 70% of the cross-section of the third full wire.