Sensor systems, devices, and methods for continuous glucose monitoring

Patent metadata

Field	Value
Publication number	US-2017181676-A1
Application number	US-201514980205-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Dec 28, 2015
Publication date	Jun 29, 2017
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 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.

Assignees

• Medtronic Minimed Inc

Inventors

• Nogueira Keith
• Engel Taly G
• Gautham Raghavendhar
• Li Xiaolong
• Liang Bradley C
• Shah Rajiv
• Kim Jaeho
• Liu Mike C
• Tsai Andy Y
• Nishida Jeffrey

Classifications

• A61B2560/0276

  Determining malfunction · CPC title

• A61B2560/0223

  of calibration, e.g. protocols for calibrating sensors · CPC title

• A61B5/7221

  Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217) · CPC title

• A61B5/14865

  invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors · CPC title

• A61B5/14532 Primary

  for measuring glucose, e.g. by tissue impedance measurement · CPC title