REFERENCE ELECTRODES HAVING AN EXTENDED LIFETIME FOR USE IN LONG TERM AMPEROMETRIC SENSORS

• US 20090294306A1
• Filed: 06/02/2008
• Published: 12/03/2009
• Est. Priority Date: 06/02/2008
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Feldman, Benjamin J., Liu, Zenghe
• Granted Patent: US 8,620,398 B2
• Time in Patent Office: Days
• US Class Current: 205/792
• CPC Class Codes: G01N 27/301 Reference electrodes

Abstract

The present application provides Ag/AgCl based reference electrodes having an extended lifetime that are suitable for use in long term amperometric sensors. Electrochemical sensors equipped with reference electrodes described herein demonstrate considerable stability and extended lifetime in a variety of conditions.

Claims

1. A method of replenishing a level of AgCl on a reference electrode of a electrochemical sensor, the method comprising:

inserting a electrochemical sensor into skin of a patient, wherein the electrochemical sensor comprises a flexible substrate comprising

(i) at least one working electrode comprising a sensing layer and a membrane disposed over the sensing layer,

(ii) at least one reference electrode comprising a layer of Ag/AgCl,

(iii) at least one contact pad coupled to each of the working and reference electrodes,

wherein the electrochemical sensor is adapted for implantation of a portion of the electrochemical sensor comprising the working and reference electrodes through skin; and

applying an electrical potential across the reference electrode and another electrode of the sensor for a period of time sufficient to convert Ag to AgCl in order to replenish the level of AgCl present on the reference electrode.

2. The method of claim 1, wherein said electrical potential is at least +50 mV.

3. The method of claim 1, wherein said electrical potential is at least +100 mV.

4. The method of claim 1, wherein said electrical potential is at least +200 mV.

5. The method of claim 1, wherein said electrical potential is applied for a duration of at least 30 seconds.

6. The method of claim 1, wherein said electrical potential is applied for a duration of at least 45 seconds.

7. The method of claim 1, wherein said electrical potential is applied for a duration of at least 1 minute.

8. The method of claim 1, wherein said application of electrical potential is repeated at least once.

9. The method of claim 1, wherein said application of electrical potential is repeated at least twice.

10. A method for monitoring a level of an analyte, the method comprising:

inserting an electrochemical sensor into skin of a patient, wherein the electrochemical sensor comprises a flexible substrate comprising

(i) at least one working electrode comprising a sensing layer and a membrane disposed over the sensing layer,

(ii) at least one reference electrode comprising a layer of Ag/AgCl,

(iii) at least one contact pad coupled to each of the working and reference electrodes,

wherein the electrochemical sensor is adapted for implantation of a portion of the electrochemical sensor comprising the working and reference electrodes through skin; and

attaching the electrochemical sensor control unit to the skin of the patient, wherein the electrochemical sensor control unit comprises

(i) a housing adapted for placement on skin;

(ii) a plurality of conductive contacts disposed on the housing and configured for coupling to the contact pads of the electrochemical sensor; and

(iii) an rf transmitter disposed in the housing and coupled to the plurality of conductive contacts for transmitting data obtained using the electrochemical sensor;

coupling a plurality of conductive contacts disposed in the sensor control unit to a plurality of contact pads disposed on the sensor;

collecting data, using the sensor control unit, regarding a level of an analyte from signals generated by the sensor;

transmitting the collected data to the display unit using the rf transmitter of the sensor control unit; and

displaying an indication of the level of the analyte on the display of the display unit,

wherein following insertion of the electrochemical sensor into skin of the patient, an electrical potential is applied across the reference electrode for a period of time sufficient to convert Ag to AgCl in order to replenish the level of AgCl present on the reference electrode.

11. The method of claim 10, wherein said electrical potential is at least +50 mV.

12. The method of claim 10, wherein said electrical potential is at least +100 mV.

13. The method of claim 10, wherein said electrical potential is at least +200 mV.

14. The method of claim 10, wherein said electrical potential is applied for a duration of at least 30 seconds.

15. The method of claim 10, wherein said electrical potential is applied for a duration of at least 45 seconds.

16. The method of claim 10, wherein said electrical potential is applied for a duration of at least 1 minute.

17. The method of claim 10, wherein said application of electrical potential is repeated at least once.

18. The method of claim 10, wherein said application of electrical potential is repeated at least twice.

19. The method of claim 10, wherein the analyte is glucose.

20. The method of claim 10, wherein collecting data comprises generating signals from the sensor and processing the signals into data.

21. The method of claim 10, wherein the data comprises the signals from the sensor.

22. The method of claim 10, further comprising activating an alarm if the data indicates an alarm condition.

23. The method of claim 10, further comprising administering a drug in response to the data.

24. The method of claim 23, wherein the drug is insulin.

25. The method of claim 24, further comprising obtaining a calibration value from a calibration device to calibrate the data.

26. The method of claim 25, wherein the calibration device is coupled to the display unit.

27. The method of claim 26, further comprising transmitting the calibration value from a transmitter in the display unit to a receiver in the sensor control unit.