Electrode systems for electrochemical sensors

An electrochemical sensor for determining a presence or a concentration of an analyte in a fluid, the sensor comprising:

• a membrane system comprising an enzyme, wherein the enzyme reacts with the analyte;
• an electroactive surface comprising a working electrode, the working electrode comprising a conductive material and configured to measure a product of the reaction of the enzyme with the analyte;
• and
• an auxiliary electrode comprising a conductive material and configured to generate oxygen, wherein the auxiliary electrode is situated such that the oxygen generated diffuses to the enzyme or to the electroactive surface, wherein the auxiliary electrode comprises a polymer, wherein the polymer is directly situated on a surface of the auxiliary electrode, and wherein the polymer comprises a material that is impermeable to glucose but is permeable to oxygen and permeable to interfering species.

An electrochemical sensor for determining a presence or a concentration of an analyte in a fluid, the sensor comprising:

• a membrane system comprising an enzyme, wherein the enzyme reacts with the analyte;
• an electroactive surface comprising a working electrode, the working electrode comprising a conductive material and configured to measure a product of the reaction of the enzyme with the analyte;
• and
• an auxiliary electrode comprising a conductive material and configured to modify an electrochemical interferant such that the electrochemical interferent is rendered substantially electrochemically non-reactive at the working electrode, wherein the auxiliary electrode comprises a polymer, wherein the polymer is situated on a surface of the auxiliary electrode, and wherein the polymer comprises a material that is impermeable to glucose but is permeable to oxygen.

An electrochemical sensor for determining a presence or a concentration of an analyte in a fluid, the sensor comprising:

• a membrane system comprising an enzyme, wherein the enzyme reacts with the analyte;
• an electroactive surface comprising a working electrode, the working electrode comprising a conductive material and configured to measure a product of the reaction of the enzyme with the analyte;
• and
• an auxiliary electrode comprising a conductive material and configured to modify an electrochemical interferant such that the electrochemical interferent is rendered substantially electrochemically non-reactive at the working electrode, wherein the auxiliary electrode comprises a polymer, wherein the polymer is situated on a surface of the auxiliary electrode, and wherein the polymer comprises a material having a molecular weight that blocks glucose and allows transport therethrough of oxygen, urate, ascorbate, and acetaminophen.