System and method for sensor recalibration

• US 7,384,397 B2
• Filed: 12/30/2003
• Issued: 06/10/2008
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Wang, Lu, Zhang, Yanan
• Primary Examiner(s): Nasser, Jr.; Robert L.
• Assistant Examiner(s): Toth; Karen E
• Application Number:
  US10/751,327
• Publication Number:
  US 20050143636A1
• Time in Patent Office: 1,624 Days
• Field of Search: 205/775, 205/777.5, 600309-367
• US Class Current: 600/365
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/4839 combined with drug delivery

Abstract

A system and method for calibrating a sensor. The method may include, without limitation, compiling an array of data relating to the sensor; adjusting a sensor parameter a first time based on data in the array; adjusting a curve representing the sensor output based on data in the array; and adjusting the sensor parameter a second time based on data in the array. The sensor may be an in vivo glucose sensor and the sensor parameter adjusted may be a current. The array may include historical as well as recent data, such as, for example, blood glucose readings and sensor electrode readings.

Claims

1. A method for adjusting a calibrating curve for a sensor calibration comprising:

compiling a calibration array of data values relating to the sensor;

generating a calibration curve;

adjusting a nominal output current of the sensor based on data in the calibration array;

adjusting the calibration curve based on the adjusted value of the nominal output current;

wherein adjusting the calibration curve representing the sensor output further comprises performing a linear regression on data in the calibration array; and

wherein a result of the linear regression determines a first calibration point.

2. The method of claim 1, wherein compiling the calibration array comprises compiling historical data.

3. The method of claim 2, wherein the historical data comprises measured blood glucose readings.

4. The method of claim 1, wherein compiling the calibration array comprises compiling recent data.

5. The method of claim 4, wherein the recent data comprises electrode readings.

6. The method of claim 5, wherein the electrode readings comprise glucose electrode readings and oxygen electrode readings.

7. The method of claim 4, wherein the recent data comprises measured blood glucose concentrations.

8. The method of claim 7, wherein the nominal output current is a nominal glucose current.

9. The method of claim 8, wherein the nominal glucose current is adjusted based on a shift of measured data points with respect to blood glucose readings.

10. The method of claim 9, wherein the shift is a mean shift.

11. The method of claim 1, wherein the first calibration point is used to determine a plurality of calibration points.

12. The method of claim 1, wherein adjusting the calibration curve representing the sensor output comprises adjusting the calibration curve in a piecewise linear fashion.

13. The method of claim 12, wherein a number of pieces in the piecewise linear adjustment is five.

14. The method of claim 1, further comprising compiling a second calibration array of data values relating to the sensor;

adjusting the nominal output current of the sensor a second time based on data in the second calibration array.

15. The method of claim 14, wherein the nominal output current is a nominal glucose current.

16. The method of claim 15, wherein the nominal glucose current is adjusted based on a shift of measured data points with respect to blood glucose readings.

17. The method of claim 16, wherein the shift is a mean shift.

18. The method of claim 1, further comprising establishing a new sensor output based on the adjusted calibration curve and the twice adjusted nominal output current.

19. The method of claim 1, wherein generating a calibration curve comprises generating a calibration curve based on a priori empirical values, and wherein the method further comprises:

compiling a plurality of data values from the sensor;

compiling independent historical values of a parameter sensed by the sensor; and

reconciling the plurality of data values from the sensor to the calibration curve using the independent historical values.

20. The method of claim 19, wherein the sensor is a glucose sensor.

21. The method of claim 19, wherein generating a calibration curve comprises compiling a priori empirical values of sensors similar to the sensor being calibrated.

22. The method of claim 19, wherein generating a calibration curve comprises generating a calibration curve representing a sensor having a plurality of phases.

23. The method of claim 19, wherein the independent historical values of a parameter sensed by the sensor are metered blood glucose values.

24. The method of claim 19, wherein reconciling the plurality of data values comprises adjusting an output current of the sensor.

25. The method of claim 24, wherein the output current of the sensor is a nominal glucose current.

26. The method of claim 25, wherein the nominal glucose current is adjusted based on a shift of the plurality of data values from the sensor with respect to metered blood glucose values.

27. The method of claim 19, wherein reconciling the plurality of data values comprises performing a linear regression on the plurality of data values.

28. The method of claim 19, wherein reconciling the plurality of data values is performed in a piecewise linear fashion.