METHODS AND SYSTEMS FOR OPTIMIZING SENSOR FUNCTION BY THE APPLICATION OF VOLTAGE

• US 20140135605A1
• Filed: 11/13/2012
• Published: 05/15/2014
• Est. Priority Date: 11/13/2012
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Gottlieb, Rebecca K., Chiu, Chia-Hung, Rao, Ashwin K.
• Granted Patent: US 9,265,455 B2
• Time in Patent Office: Days
• US Class Current: 600/347
• CPC Class Codes: A61B 2560/0204 of power management
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• 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 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence

Abstract

A method is provided for initializing an analyte sensor, such as a glucose sensor. Where a sensor has been disconnected and reconnected, a disconnection time is determined and a sensor initialization protocol is selected based upon the disconnection time. The sensor initialization protocol may include applying a first series of voltage pulses to the sensor. A method for detecting hydration of a sensor is also provided.

Claims

1. A method of initializing an analyte sensor, comprising:

determining a disconnection time, wherein the disconnection time is the amount of time the sensor has been disconnected from sensor electronics,

selecting an initialization protocol based on the disconnection time, the initialization protocol selected from the group consisting of;

a first initialization scheme comprising a first series of voltage pulses and a second initialization scheme comprising a second series of voltage pulses,

wherein the first initialization scheme is selected if the disconnection time falls within a first time range and the second initialization scheme is selected if the disconnection time falls within a second time range; and

applying the selected initialization protocol to the sensor.

2. The method of claim 1, wherein the initialization protocol is selected from the group further consisting of a third initialization scheme comprising the application of no voltage to the sensor, wherein the third initialization scheme is selected if the disconnection time is less than the first time range and the second time range.

3. The method of claim 1, further comprising applying a stabilization voltage to the sensor, after applying the selected initialization voltage, for a first stabilization time.

4. The method of claim 3, further comprising:

determining whether the sensor is stable after applying the first stabilization voltage; and

if the sensor is not stable, applying a second stabilization voltage to the sensor for a second stabilization time.

5. The method of claim 4, further comprising calibrating the sensor if the sensor is stable.

6. The method of claim 5, wherein calibrating the sensor includes measuring blood glucose using a blood glucose meter.

7. The method of claim 5, wherein calibration of the sensor is only performed if the disconnection time falls within the first or second time range.

8. The method of claim 4, wherein if the sensor is not stable after a predetermined maximum stabilization time, the initialization protocol is ended so that a new sensor may be connected to the sensor electronics.

9. The method of claim 8, wherein the maximum stabilization time is 30 minutes.

10. The method of claim 1, wherein the determining a disconnection time includes measuring the current output of the sensor and comparing the measured current output to a disconnection threshold value.

11. The method of claim 10, wherein the determining a disconnection time further includes comparing the current output to a reconnection threshold value.

12. The method of claim 10, wherein the disconnection threshold value is 0.6 nA.

13. The method of claim 1, wherein the first time range is a disconnection time of greater than 120 minutes.

14. The method of claim 1, wherein the second time range is 10 minutes to 120 minutes.

15. The method of claim 1, wherein the second initialization scheme comprises application of at least two voltages to the sensor for a predetermined second initialization time.

16. The method of claim 15, wherein the at least two voltages are a series of stepped down voltages.

17. The method of claim 15, wherein the predetermined second initialization time is less than 30 minutes.

18. The method of claim 1, further comprising detecting hydration of the sensor prior to applying the selected initialization protocol, wherein detecting hydration includes:

applying a series of hydration pulses to the sensor for a first hydration time;

recording the current response of the sensor during application of the series of hydration pulses; and

comparing the current response to a predetermined hydration threshold.

19. The method of claim 18, wherein application of the series of hydration pulses is terminated if the current response reaches or exceeds the predetermined hydration threshold.

20. The method of claim 18, wherein the detecting hydration further includes applying a second series of hydration pulses to the sensor for a second hydration time if the current response does not reach the predetermined hydration threshold during the first predetermined hydration time.

21. The method of claim 18, wherein the predetermined hydration threshold is 100 nA.

22. A method of initializing an analyte sensor, comprising:

determining a disconnection time, wherein the disconnection time is the amount of time a sensor has been disconnected from sensor electronics,

selecting an initialization protocol based on the disconnection time, the initialization protocol selected from the group consisting of;

a first initialization scheme comprising a first series of voltage pulses, a second initialization scheme comprising a second series of voltage pulses, and a third initialization scheme comprising the application of no voltage to the sensor,

wherein the first initialization scheme is selected if the disconnection time falls within a first time range, the second initialization scheme is selected if the disconnection time falls within a second time range, and the third initialization scheme is selected if the disconnection time is less than the first time range and the second time range;

applying the selected initialization protocol to the sensor; and

applying a stabilization voltage to the sensor for a first stabilization time.