Electrochemical sensors

Abstract

Described herein are substrates, sensors and systems related to measuring the concentration of an analyte such as hydrogen ion in a sample. Redox active moieties whose reduction and/or oxidation potentials are sensitive to the presence of an analyte are immobilized onto a surface of an electrode. Immobilized redox active moieties whose reduction and/or oxidation potential are insensitive to the analyte can be used for reference. Voltammetric measurements made using such modified surfaces can accurately determine the presence and/or concentrations of analytes in a sample of interest. The electrochemical sensors of the invention are robust and can be made so as not to require calibration or re-calibration.

1 .- 27 . (canceled) 
     
     
         28 . A sensor, comprising:
 a solid state electrode comprising a non-metallic substrate having a surface having immobilized thereon a redox-active moiety, wherein the solid state electrode exhibits an oxidation potential and/or a reduction potential that is sensitive to the presence of an analyte at an accuracy of plus or minus about 10% or less when in use or storage for about ten hours or more,   wherein the redox-active moiety is immobilized on the surface through a carbon covalent bond, and   wherein the sensor is capable of measuring analyte concentration from about 10 −13  moles per liter to about 10 −2  moles per liter.   
     
     
         29 . The sensor of  claim 28 , further comprising an additional solid state electrode having an oxidation potential and/or reduction potential that is insensitive to the presence of the analyte. 
     
     
         30 . The sensor of  claim 28 , wherein the non-metallic substrate comprises silicon. 
     
     
         31 . The sensor of  claim 28 , wherein the solid state electrode exhibits an oxidation potential and/or reduction potential that is sensitive to the presence of the analyte at an accuracy of plus or minus about 5% or less when in use or storage for about ten hours or more. 
     
     
         32 . The sensor of  claim 28 , wherein the solid state electrode exhibits an oxidation potential and/or reduction potential that is sensitive to the presence of the analyte at an accuracy of plus or minus about 1% or less when in use or storage for about ten hours or more. 
     
     
         33 . The sensor of  claim 28 , wherein the sensor is disposable or single-use. 
     
     
         34 . A sensor, comprising:
 a first working electrode comprising a first non-metallic substrate having immobilized thereon a first redox-active moiety, wherein the first working electrode exhibits an oxidation potential and/or a reduction potential that is sensitive to the presence of an analyte; and   a second working electrode comprising a second non-metallic substrate having immobilized thereon a second redox-active moiety, wherein the second working electrode exhibits an oxidation potential and/or reduction potential that is insensitive to the presence of the analyte,   wherein the first or second non-metallic substrate has a resistivity of about 0.001 ohm-centimeters or more.   
     
     
         35 . The sensor of  claim 34 , wherein the analyte is hydrogen ion, carbon monoxide, oxygen, ammonia, or an alkali metal. 
     
     
         36 . The sensor of  claim 35 , wherein the analyte is hydrogen ion and the sensor has an accuracy to within about 1 pH units or less. 
     
     
         37 . The sensor of  claim 35 , wherein the analyte is hydrogen ion and the sensor has an accuracy to within about 0.5 pH units or less. 
     
     
         38 . The sensor of  claim 34 , wherein the first non-metallic substrate or second non-metallic substrate comprises silicon. 
     
     
         39 . The sensor of  claim 35 , wherein the analyte is hydrogen ion and the sensor has a sensitivity of at least about 45.1 mV per pH unit. 
     
     
         40 . The sensor of  claim 34 , wherein the sensor is accurate at measuring the concentration of the analyte to about 10% or less while in use or storage for about ten hours or more. 
     
     
         41 . The sensor of  claim 34 , wherein the sensor is accurate at measuring the concentration of the analyte to about 1% or less while in use or storage for about ten hours or more. 
     
     
         42 . The sensor of  claim 34 , wherein the resistivity of the second non-metallic substrate is different than the resistivity of the first non-metallic substrate. 
     
     
         43 . A sensor, comprising:
 a solid state electrode comprising a non-metallic substrate having a surface having immobilized thereon a redox-active moiety, wherein the solid state electrode exhibits an oxidation potential and/or a reduction potential that is sensitive to the presence of an analyte; and   a microprocessor programmed to measure the concentration of the analyte in a concentration range from about 10 −13  moles per liter to about 10 −2  moles per liter without calibration or re-calibration when in use or storage for about ten hours or more.   
     
     
         44 . The sensor of  claim 43 , further comprising an additional solid state electrode having an oxidation potential and/or reduction potential that is insensitive to the presence of the analyte. 
     
     
         45 . The sensor of  claim 43 , wherein the non-metallic substrate comprises silicon. 
     
     
         46 . The sensor of  claim 43 , wherein the analyte is hydrogen ion, carbon monoxide, oxygen, ammonia, or an alkali metal. 
     
     
         47 . The sensor of  claim 43 , wherein the electrode is substantially planar.