Metal-enzyme sandwich layers

Abstract

Measurement of target analytes is carried out with an enzyme-based sensor. The enzyme hydrogel is protected by a porous layer of a metallic material. The size of the pores is small enough to prevent degradation of the enzyme layer caused by the immune system of an organism, but large enough to allow transfer of molecules that participate in the electrochemical reaction allowing the enzyme to detect the target analytes.

1 . (canceled) 
     
     
         2 . A sensing device comprising:
 a substrate; and   a working electrode on the substrate;   the working electrode comprising:
 a metallic layer contacting the substrate; 
 an enzyme layer contacting the metallic layer, the enzyme layer having larger lateral dimensions than the metallic layer; and 
 a metallic porous layer contacting the enzyme layer, the metallic porous layer being separated from the metallic layer by the enzyme layer. 
   
     
     
         3 . The sensing device of  claim 2 , wherein the enzyme layer comprises an imperfect enzyme sensing layer and a porous electrical insulator over the imperfect enzyme sensing layer. 
     
     
         4 . The sensing device of  claim 3 , wherein the porous electrical insulator comprises polyurethane. 
     
     
         5 . The sensing device of  claim 3 , wherein the porous electrical insulator comprises a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer. 
     
     
         6 . The sensing device of  claim 2 , wherein the metallic layer comprises an array of nanopillars. 
     
     
         7 . The sensing device of  claim 2 , wherein the metallic porous layer comprises an array of pores having a diameter between 2 nm and 2 micrometers. 
     
     
         8 . The sensing device of  claim 7 , wherein the metallic porous layer comprises an array of pores having a diameter smaller than 200 nm. 
     
     
         9 . The sensing device of  claim 8 , wherein the metallic porous layer comprises an array of pores having a diameter smaller than 20 nm. 
     
     
         10 . The sensing device of  claim 7 , wherein the array of pores has a total area between 0.001% and 50% of a total area of the metallic porous layer. 
     
     
         11 . The sensing device of  claim 7 , wherein the array of pores has a total area between 0.1% and 10% of a total area of the metallic porous layer. 
     
     
         12 . The sensing device of  claim 10 , wherein the metallic porous layer is made of a material selected from the group consisting of: Pt, Au, W, Ti, Pd, Ir, Si, TiO2, WO3, SnO2, graphene, and InO2. 
     
     
         13 . The sensing device of  claim 2 , wherein the metallic porous layer comprises an array of pores having a diameter larger than molecules taking part in the electrochemical reaction. 
     
     
         14 . The sensing device of  claim 2 , wherein the enzyme layer contacts the substrate and the metallic porous layer contacts the substrate. 
     
     
         15 . The sensing device of  claim 2 , wherein the metallic layer has a thickness between 1 nm and 1 mm. 
     
     
         16 . The sensing device of  claim 15 , wherein the metallic porous layer has a thickness between 1 nm and 10 micrometers. 
     
     
         17 . The sensing device of  claim 16 , wherein the enzyme layer has a thickness less than 10 micrometers. 
     
     
         18 . The sensing device of  claim 17 , wherein the enzyme layer has a thickness less than 1 micrometer. 
     
     
         19 . The sensing device of  claim 16 , wherein the enzyme layer has a thickness less than 400 nm. 
     
     
         20 . The sensing device of  claim 2 , wherein the enzyme layer comprises an oxidase enzyme and a hydrogel. 
     
     
         21 . The sensing device of  claim 2 , further comprising:
 a counter electrode on the substrate; and   a reference electrode on the substrate,   wherein:   the counter electrode comprises:
 a metallic layer contacting the substrate; 
   an enzyme layer on the metallic layer; and
 a metallic porous layer on the enzyme layer, and 
   the reference electrode comprises:
 a metallic layer contacting the substrate; 
 an enzyme layer on the metallic layer; and 
 a metallic porous layer on the enzyme layer. 
   
     
     
         22 . The sensing device of  claim 2 , wherein the enzyme layer comprises glutaraldehyde. 
     
     
         23 . An array of sensing devices, each sensing device of the array as described in  claim 2 , wherein a spacing between the sensing devices of the array of sensing devices is configured to avoid crosstalk due to leakage of intermediate reporting molecules. 
     
     
         24 . The array of  claim 23 , wherein the spacing is between 10 and 250 nm. 
     
     
         25 . The sensing device of  claim 2 , wherein the sensing device is configured to be implanted internally to an organism, or attached externally to skin of the organism.