SENSOR SYSTEMS, DEVICES, AND METHODS FOR CONTINUOUS GLUCOSE MONITORING

• US 20170181676A1
• Filed: 12/28/2015
• Published: 06/29/2017
• Est. Priority Date: 12/28/2015
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Kim, Jaeho, Gautham, Raghavendhar, Li, Xiaolong, Liang, Bradley C., Nogueira, Keith, Nishida, Jeffrey, Engel, Taly G., Shah, Rajiv, Liu, Mike C., Tsai, Andy Y.
• Granted Patent: US 10,327,680 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence

Abstract

Electrochemical impedance spectroscopy (EIS) may be used in conjunction with continuous glucose monitoring (CGM) to enable identification of valid and reliable sensor data, as well implementation of Smart Calibration algorithms.

Claims

1. A method for signal dip detection during the first 4-12 hours of glucose sensor data, said glucose sensor including physical sensor electronics, a microcontroller, and a working electrode, and being in operational contact with a display device configured to display said data to a user, the method comprising:

(a) performing, by said microcontroller, an electrochemical impedance spectroscopy (EIS) procedure to obtain real impedance values for said electrode;

(b) periodically measuring, by said physical sensor electronics, values of the electrode current (Isig) for the working electrode;

(c) calculating, by said microcontroller, sensor glucose (SG) values associated with said Isig values;

(d) comparing a current value of the Isig to a first threshold and the current value of the SG to a second threshold;

(e) evaluating, by said microcontroller, a trend of said real impedance values; and

based on said comparison and said evaluation, determining whether a dip event exists.

2. The method of claim 1, wherein said real impedance values are 1 kHz real impedance values.

3. The method of claim 1, wherein the real impedance values are unfiltered.

4. The method of claim 1, wherein said first threshold is 18 nA.

5. The method of claim 1, wherein said second threshold is 80 mg/dL.

6. The method of claim 1, wherein a dip event is determined to exist if the current value of the Isig is less that said first threshold, the current value of SG is less than said second threshold, and said trend evaluation indicates that the 2 most-recent values of real impedance are increasing.

7. The method of claim 6, further including blanking display of said SG values on said display device if a dip event is determined to exist.

8. The method of claim 1, wherein the sensor includes a plurality of working electrodes, and steps (a)-(f) are performed for each of the plurality of electrodes.

9. A method for signal dip detection during the first 4 hours of glucose sensor data, said glucose sensor including physical sensor electronics, a microcontroller, and a working electrode, and being in operational contact with a display device configured to display said data to a user, the method comprising:

(a) performing, by said microcontroller, an electrochemical impedance spectroscopy (EIS) procedure to obtain real impedance values for said electrode;

(b) periodically measuring, by said physical sensor electronics, values of the electrode current (Isig) for the working electrode;

(c) comparing a current value of the Isig to a first threshold;

(d) evaluating, by said microcontroller, a trend of said real impedance values; and

(e) based on said comparison and said evaluation, determining whether a dip event exists.

10. The method of claim 9, wherein a dip event is determined to exist if the current value of the Isig is less that said threshold, and said trend evaluation indicates that the 2 most-recent values of real impedance are increasing.

11. The method of claim 10, further including blanking display of said sensor data on said display device if a dip event is determined to exist.

12. The method of claim 9, wherein said threshold is 25 nA.

13. The method of claim 9, wherein the real impedance values are unfiltered.

14. The method of claim 13, wherein said real impedance values are 1 kHz real impedance values.

15. The method of claim 9, further including blanking display of said sensor data on said display device if a dip event is determined to exist.

16. The method of claim 15, wherein, after blanking of sensor data has started, the method further includes determining, by said microcontroller, whether blanking should continue by comparing the current value of the Isig to a second threshold value.

17. The method of claim 16, wherein said second threshold value is 1.2 times the value of Isig at the start of said dip event.

18. The method of claim 17, wherein data blanking continues if the current value of Isig is greater than said second threshold value.

19. The method of claim 17, wherein data blanking is terminated if the current value of Isig is not greater than said second threshold value.

20. The method of claim 9, wherein the sensor includes a plurality of working electrodes, and steps (a)-(e) are performed for each of the plurality of electrodes.