ELECTRODE SYSTEMS FOR ELECTROCHEMICAL SENSORS

• US 20140001042A1
• Filed: 08/29/2013
• Published: 01/02/2014
• Est. Priority Date: 07/25/2003
• Status: Abandoned Application

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Simpson, Peter C., Petisce, James R., Carr-Brendel, Victoria E., Brauker, James H.
• Application Number:
  US14/014,216
• Publication Number:
  US 20140001042A1
• Time in Patent Office: Days
• US Class Current: 204/403.1
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

Abstract

The present invention relates generally to systems and methods for improved electrochemical measurement of analytes. The preferred embodiments employ electrode systems including an analyte-measuring electrode for measuring the analyte or the product of an enzyme reaction with the analyte and an auxiliary electrode configured to generate oxygen and/or reduce electrochemical interferants. Oxygen generation by the auxiliary electrode advantageously improves oxygen availability to the enzyme and/or counter electrode; thereby enabling the electrochemical sensors of the preferred embodiments to function even during ischemic conditions. Interferant modification by the auxiliary electrode advantageously renders them substantially non-reactive at the analyte-measuring electrode, thereby reducing or eliminating inaccuracies in the analyte signal due to electrochemical interferants.

Claims

1. 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 interferent such that the electrochemical interferent is rendered substantially electrochemically non-reactive at the working electrode.

2. The electrochemical sensor of claim 1, wherein the auxiliary electrode comprises a conductive material selected from the group consisting of a conductive metal, a conductive polymer, and a blend of a conductive metal and a conductive polymer.

3. The electrochemical sensor of claim 1, wherein the auxiliary electrode comprises a form selected from the group consisting of a mesh, a grid, and a plurality of spaced wires.

4. The electrochemical sensor of claim 1, wherein the auxiliary electrode comprises a polymer, wherein the polymer is situated on a surface of the auxiliary electrode.

5. The electrochemical sensor of claim 4, wherein the polymer comprises a material that is permeable to an electrochemical interferent.

6. The electrochemical sensor of claim 4, wherein the polymer comprises a material that is impermeable to glucose but is permeable to oxygen.

7. The electrochemical sensor of claim 4, wherein the polymer comprises a material that is impermeable to glucose but is permeable to oxygen and interferents.

8. The electrochemical sensor of claim 4, wherein the polymer comprises a material having a molecular weight that blocks glucose and allows transport therethrough of oxygen, urate, ascorbate, and acetaminophen.

9. The electrochemical sensor of claim 4, wherein the polymer comprises a material that is permeable to glucose and oxygen.

10. The electrochemical sensor of claim 4, wherein the polymer comprises a material that is permeable to glucose, oxygen, and interferents.

11. The electrochemical sensor of claim 10, wherein the polymer comprises a material having a molecular weight that allows transport therethrough of oxygen, glucose, urate, ascorbate, and acetaminophen.

12. The electrochemical sensor of claim 1, wherein the auxiliary electrode is configured to be set at a potential of at least about +0.1 V.

13. The electrochemical sensor of claim 1, wherein the auxiliary electrode is configured to generate oxygen.

14. The electrochemical sensor of claim 13, wherein the auxiliary electrode is configured to be set at a potential of at least about +0.6 V.

15. An electrochemical sensor comprising:

an electroactive surface configured to measure an analyte; and

an auxiliary interferent-modifying electrode configured to modify an electrochemical interferant such that the electrochemical interferent is rendered substantially non-reactive at the electroactive surface.

16. The electrochemical sensor of claim 15, wherein the auxiliary interferent-modifying electrode comprises a conductive material selected from the group consisting of a conductive metal, a conductive polymer, and a blend of a conductive metal and a conductive polymer.

17. The electrochemical sensor of claim 15, wherein the auxiliary interferent- modifying electrode comprises a form selected from the group consisting of a mesh, a grid, and a plurality of spaced wires.

18. The electrochemical sensor of claim 15, wherein the auxiliary interferent-modifying electrode comprises a polymer, wherein the polymer is situated on a surface of the auxiliary interferent-modifying electrode.