Sensor systems, devices, and methods for continuous glucose monitoring

Patent metadata

Field	Value
Publication number	US-2019041345-A1
Application number	US-201816158043-A
Country	US
Kind code	A1
Filing date	Oct 11, 2018
Priority date	Dec 28, 2015
Publication date	Feb 7, 2019
Grant date	—

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.

First claim

What is claimed is:

1 . A method of optimizing operation of a glucose sensor, 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 glucose sensor 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) filtering, by said microcontroller, said real impedance values; (c) analyzing said real impedance values by said microcontroller to determine whether said values are stable; (d) if said real impedance values are stable, comparing, by said microcontroller, the most-recent real impedance value to a first threshold value; (e) based on said comparison, determining, by said microcontroller, whether said sensor data is valid; and (f) transmitting, by said microcontroller, the glucose sensor data to be displayed on said display device when said data is determined to be valid, and blanking, by said microcontroller, the glucose sensor data to the user when said data is determined to be invalid.

2 . The method of claim 1 , wherein said first threshold value is 10,000Ω.

3 . The method of claim 2 , wherein the sensor data is determined to be valid if the most-recent real impedance value is less than the first threshold value.

4 . The method of claim 3 , wherein, if the most-recent real impedance value is greater than the first threshold value, the method further includes determining, by the microcontroller, whether said real impedance values have exceeded a second threshold over a period of time.

5 . The method of claim 4 , wherein said period of time is the past 3 hours.

6 . The method of claim 5 , wherein, if it is determined that the real impedance values have exceeded said second threshold over the past 3 hours, then said sensor is terminated.

7 . The method of claim 5 , wherein, if it is determined that the real impedance values have not exceeded said second threshold over the past 3 hours, then said sensor data is determined to be invalid and is not displayed on the display device.

8 . The method of claim 7 , further including periodically repeating steps (a) (e).

9 . The method of claim 8 , wherein, once the sensor data is determined to be valid, said data is transmitted to be displayed on said display device.

10 . The method of claim 4 , wherein said second threshold is between about 10,000Ω and about 12,000Ω.

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

12 . A method of optimizing operation of a glucose sensor, said glucose sensor including physical sensor electronics, a microcontroller, and a working electrode, the method comprising:
(a) performing, by said microcontroller, an electrochemical impedance spectroscopy (EIS) procedure to obtain imaginary impedance values for said electrode; (b) calculating, by said sensor electronics, a change value as a difference between a threshold reference for said imaginary impedance values and the most-recent imaginary impedance value; (c) obtaining, by said microcontroller, measurements of the calibration factor for said glucose sensor; (d) comparing, by said microcontroller, said change value to a first threshold and said calibration factor to a second threshold; (e) based on said comparison, determining, by said microcontroller, whether sensor data from said glucose sensor is valid; and (f) continuing, by said microcontroller, to operate the glucose if said sensor data is valid, and terminating the glucose sensor, by said microcontroller, if said sensor data is invalid.

13 . The method of claim 12 , wherein the sensor data is determined to be valid if either the calibration factor is less than the second lower threshold or the change value is less than the first lower threshold for two consecutive measurements of the change value.

14 . The method of claim 12 , further including terminating the sensor if the change value is greater than the first threshold for two consecutive measurements of the change value, and the calibration factor is greater than said second threshold.

15 . The method of claim 12 , wherein said change value is calculated as the absolute difference between the threshold reference and the most-recent imaginary impedance value.

16 . The method of claim 12 , wherein said imaginary impedance values are 8 kHz imaginary impedance values.

17 . The method of claim 12 , wherein said threshold reference is calculated as the minimum 8 kHz imaginary impedance value since sensor initialization.

18 . The method of claim 17 , wherein said threshold reference is clipped so as to fall within the range −1,000Ω and 800Ω.

19 . The method of claim 12 , wherein the sensor includes a plurality of working electrodes, and steps (a)-(f) are performed for each of the plurality of electrodes.

20 . The method of claim 12 , wherein said first threshold value is 1,200Ω and said second threshold value is 14 mg/dL/nA.

Assignees

• Medtronic Minimed Inc

Inventors

• Nogueira Keith
• Engel Taly G
• Li Xiaolong
• Liang Bradley C
• Shah Rajiv
• Kim Jaeho
• Liu Mike C
• Tsai Andy Y
• Varsavsky Andrea
• Yu Fei

Classifications

• G01N27/30

  Electrodes, e.g. test electrodes; Half-cells (G01N27/414 takes precedence) · CPC title

• G01N33/49

  Blood {(chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80)} · CPC title

• G01N33/48707

  by electrical means (G01N33/49, G01N33/493 take precedence) · CPC title

• G01N27/026 Primary

  Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02) · CPC title

• G01N27/07 Primary

  Construction of measuring vessels; Electrodes therefor · CPC title