ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY ENABLED CONTINUOUS GLUCOSE MONITORING SENSOR SYSTEMS

• US 20110040163A1
• Filed: 08/16/2010
• Published: 02/17/2011
• Est. Priority Date: 08/14/2009
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Fei, Jiangfeng, Reynolds, Jeffrey S., Gifford, Raeann, Telson, Stanley A.
• Granted Patent: US 8,868,151 B2
• Time in Patent Office: Days
• US Class Current: 600/347
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement

Abstract

The use of electrical impedance spectroscopy to adjust calibration settings in an in vivo monitoring system, such as an in vivo continuous glucose monitoring sensor. The adjustments can compensate for the condition of the sensor membrane in vivo.

Claims

1. A method of testing the condition of a continuous analyte monitoring sensor in vivo comprising:

obtaining a reference parameter value for the continuous analyte sensor;

inserting the continuous analyte sensor in vivo;

performing electrochemical impedance spectroscopy on the in vivo sensor to obtain an in vivo parameter value;

comparing the in vivo parameter value to the reference parameter value to identify particular characteristics of the in vivo sensor.

2. The method of claim 1, wherein the step of performing electrochemical impedance spectroscopy is conducted during in vivo insertion and the reference parameter value and the in vivo parameter value are impedance values.

3. The method of claim 2, wherein the in vivo capacitance value is zero or intermittently zero during insertion when the sensor is not in sufficient contact with interstitial fluid or the external counter electrode is not in contact with the skin.

4. The method of claim 3, further comprising warning the user to reinsert the sensor.

5. The method of claim 2, wherein the in vivo capacitance value is greater than the reference capacitance value during insertion when the sensor coating is damaged.

6. The method of claim 5, further comprising warning the user to replace the sensor.

7. The method of claim 2, wherein the in vivo capacitance value is less than the reference capacitance value during insertion when the sensor coating is intact.

8. The method of claim 1, wherein the step of performing electrochemical impedance spectroscopy is conducted after in vivo insertion and the reference parameter value and the in vivo parameter value are capacitance values.

9. The method of claim 8, wherein the in vivo capacitance value is zero, or intermittently zero, when adverse sensor movement exists.

10. The method of claim 9, further comprising warning the user to replace the sensor.

11. The method of claim 8, wherein the in vivo capacitance value is lower than the reference capacitance value when the sensor has been biofouled.

12. The method of claim 11, further comprising adjusting a calibration profile of the in vivo sensor.

13. The method of claim 8, wherein the in vivo capacitance value is equal to the reference capacitance value when the sensor remains intact.

14. The method of claim 8, wherein the in vivo capacitance value is greater than the reference capacitance value when the sensor membrane coating is eroded, damaged, or abused.

15. The method of claim 14, further comprising adjusting a calibration profile of the in vivo sensor.

16. The method of claim 8, wherein the step of performing electrochemical impedance spectroscopy is conducted periodically.

17. The method of claim 16, wherein the results of such periodic electrochemical impedance spectroscopy are utilized to adjust a sensor calibration profile.

18. The method of claim 8, further comprising adjusting a calibration profile of the in vivo sensor based on the comparison of the in vivo capacitance value to the reference capacitance value.

19. The method of claim 18, wherein the steps of comparing and adjusting are performed periodically.

20. The method of claim 1, wherein the step of obtaining is conducted after the step of inserting.

21. The method of claim 1, wherein the reference parameter value is an in vitro parameter value.

22. The method of claim 1, wherein the step of comparing is conducted by a Bode plot to identify phase shifts.

23. A method of testing a continuous glucose sensor in vivo comprising:

obtaining a reference impedance value for the continuous glucose sensor;

inserting the continuous glucose sensor in vivo;

performing electrochemical impedance spectroscopy on the in vivo sensor to obtain an in vivo impedance value;

comparing the in vivo impedance value to the reference impedance value to test the condition of the continuous glucose sensor.

24. The method of claim 23, further comprising:

performing electrochemical impedance spectroscopy on the in vivo sensor to obtain a first in vivo capacitance value;

performing electrochemical impedance spectroscopy on the in vivo sensor to obtain a second in vivo capacitance value;

comparing the second in vivo capacitance value to the first in vivo capacitance value to adjust a calibration profile of the continuous glucose sensor in vivo.

25. The method of claim 24, wherein the first in vivo capacitance value and the second in vivo capacitance value are obtained at approximately 100 KHz.