Method and system for remedying sensor malfunctions detected by electrochemical impedance spectroscopy

1. A method of maintaining a sensor in real time, comprising:

inserting a sensor into subcutaneous tissue;

hydrating the sensor with interstitial fluid for a hydration period;

verifying the sensor is properly hydrated by performing a first diagnostic Electrochemical Impedance Spectroscopy (EIS) procedure during the hydration period;

prolonging the hydration period if the first diagnostic EIS procedure indicates insufficient hydration, or initiating sensor power up if the first diagnostic EIS procedure indicates sufficient hydration; and

determining whether the sensor is operating normally by comparing sensor impedance values to a preset boundary having an upper and a lower threshold value,

wherein the first diagnostic EIS procedure utilizes a set DC bias and an AC voltage of varying frequencies are added to the DC bias to create a perturbation signal.

2. The method of claim 1 further comprising:

performing another diagnostic EIS procedure on a periodic basis throughout the life of the sensor.

3. The method of claim 1 , wherein an abnormal sensor reading triggers a subsequent diagnostic EIS procedure.

4. The method of claim 1 , further comprising:

applying a sensor remedial action if the sensor impedance values fall outside the boundary.

5. The method of claim 4 , wherein the sensor remedial action applies a reversed DC voltage.

6. The method of claim 4 , wherein the sensor remedial action applies a reversed DC voltage coupled with an AC voltage.

7. The method of claim 4 , further comprising:

performing an additional diagnostic EIS procedure to determine updated sensor impedance values after applying the remedial action; and

comparing the updated sensor impedance values to the boundary to determine if the sensor impedance values fall within the boundary.

8. The method of claim 7 , further comprising:

terminating the use of the sensor if the updated sensor impedance values fall outside the boundary.

9. The method of claim 7 , further comprising:

generating a message requesting the user to calibrate the sensor if the updated sensor impedance values fall outside the boundary.

10. The method of claim 7 , further comprising:

waiting and performing remedial action again if impedance values indicate the earlier remedial action was partially successful but impedance values still do not fall within the boundary.

11. A system to maintain an implantable sensor in real time, comprising:

a means for performing a diagnostic EIS procedure during the life of a sensor to derive sensor impedance values; and

a sensor implanted into subcutaneous tissue, the sensor having an electrode configuration to generate sensor signals as a result of performing a plurality of diagnostic EIS procedures during the life of the sensor;

electronic circuitry to determine whether the sensor is operating normally by comparing the sensor impedance values to a preset boundary having an upper and a lower threshold value,

wherein the plurality of EIS procedures utilize a set DC bias and an AC voltage of varying frequencies are added to the DC bias to create a perturbation signal.

12. The system of claim 11 , wherein the plurality of diagnostic EIS procedures is performed on a periodic basis throughout the life of the sensor.

13. The system of claim 11 , wherein one of the plurality of diagnostic EIS procedures is triggered by an abnormal sensor reading.

14. The system of claim 11 ,

wherein a sensor remedial action is initiated if the sensor impedance values fall outside the boundary.

15. The system of claim 14 , wherein the sensor remedial action applies a reversed DC voltage.

16. The system of claim 14 , wherein the sensor remedial action applies a reversed DC voltage coupled with an AC voltage.

17. The system of claim 14 , wherein

an additional diagnostic EIS procedure is performed to determine updated sensor impedance values after applying the remedial action; and

the updated sensor impedance values are compared to the boundary to determine if the sensor impedance values fall within the boundary.

18. The system of claim 17 , wherein

the use of the sensor is terminated if the updated sensor impedance values fall outside the boundary.

19. The system of claim 17 , wherein

a message requesting the user to calibrate the sensor is generated if the updated sensor impedance values fall outside the boundary.

20. The system of claim 17 , wherein

another remedial action is performed if the updated sensor impedance values indicate a previous remedial action was partially successful but the updated sensor impedance values still do not fall within the boundary.