Application of electrochemical impedance spectroscopy in sensor systems, devices, and related methods

Patent metadata

Field	Value
Publication number	US-9861746-B2
Application number	US-201313778559-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Jun 8, 2012
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A diagnostic Electrochemical Impedance Spectroscopy (EIS) procedure is applied to measure values of impedance-related parameters for one or more sensing electrodes. The parameters may include real impedance, imaginary impedance, impedance magnitude, and/or phase angle. The measured values of the impedance-related parameters are then used in performing sensor diagnostics, calculating a highly-reliable fused sensor glucose value based on signals from a plurality of redundant sensing electrodes, calibrating sensors, detecting interferents within close proximity of one or more sensing electrodes, and testing surface area characteristics of electroplated electrodes. Advantageously, impedance-related parameters can be defined that are substantially glucose-independent over specific ranges of frequencies. An Application Specific Integrated Circuit (ASIC) enables implementation of the EIS-based diagnostics, fusion algorithms, and other processes based on measurement of EIS-based parameters.

First claim

What is claimed is:

1. A method for real-time detection of low start-up for a working electrode of a glucose sensor, the method comprising:
inserting the sensor into subcutaneous tissue;
periodically performing an electrochemical impedance spectroscopy (EIS) procedure to generate multiple sets of impedance-related data for said working electrode;
calculating, by a microprocessor, for each of said multiple sets of impedance-related data, respective values of 1 kHz real impedance and Nyquist slope;
monitoring and analyzing, by said microprocessor, said respective values of 1 kHz real impedance and Nyquist slope over time by comparing the 1 kHz real impedance and Nyquist slope to respective specified ranges for said real impedance and Nyquist slope; and
based on said monitoring and analyzing, determining, by said microprocessor, whether said working electrode is experiencing low start-up,
wherein use of said sensor for glucose measurement is delayed or sensor glucose values are blinded to a user of the sensor by the microprocessor based on the determination that the working electrode is experiencing low start-up.

2. The method of claim 1 , wherein said EIS procedure is perfouned for a predetermined range of frequencies.

3. The method of claim 1 , wherein each of said multiple sets of impedance-related data includes values for imaginary impedance.

4. The method of claim 1 , wherein the Nyquist slope is calculated at relatively-lower frequencies.

5. The method of claim 1 , wherein each of said multiple sets of impedance-related data includes values for at least one impedance-related parameter that is substantially glucose-independent.

6. The method of claim 1 , wherein said respective values of 1 kHz real impedance and Nyquist slope are substantially glucose-independent.

7. A method for real-time detection of low start-up for a plurality of working electrodes of a glucose sensor, the method comprising:
inserting the sensor into subcutaneous tissue;
periodically performing an electrochemical impedance spectroscopy (EIS) procedure for each of said plurality of working electrodes to generate respective multiple sets of impedance-related data for each of the plurality of working electrodes;
calculating, by a microprocessor, for each of said multiple sets of impedance-related data, respective values of 1 kHz real impedance and Nyquist slope;
monitoring and analyzing, by said microprocessor, said respective values of 1 kHz real impedance and Nyquist slope over time by comparing the respective values of 1 kHz real impedance and Nyquist slope amongst the plurality of working electrodes;
based on said monitoring and analyzing, determining, by said microprocessor, whether at least one of said plurality of working electrodes is not experiencing low start-up; and
identifying, by said microprocessor, said at least one of said plurality of working electrodes for use to measure glucose.

8. The method of claim 7 , wherein said EIS procedure is performed for a predetermined range of frequencies.

9. The method of claim 7 , wherein each of said multiple sets of impedance-related data includes values for imaginary impedance.

10. The method of claim 7 , wherein the Nyquist slope is calculated at relatively-lower frequencies.

11. The method of claim 7 , wherein each of said multiple sets of impedance-related data includes values for at least one impedance-related parameter that is substantially glucose-independent.

12. The method of claim 7 , wherein said respective values of 1 kHz real impedance and Nyquist slope are substantially glucose-independent.

Assignees

• Medtronic Minimed Inc

Inventors

• Gautham Raghavendhar
• Yang Ning
• Shah Rajiv

Classifications

• A61B5/14865

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

• A61B5/14532

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

• A61B2562/04

  Arrangements of multiple sensors of the same type · CPC title

• A61M5/14244

  adapted to be carried by the patient, e.g. portable on the body · CPC title

• A61B5/6846

  specially adapted to be brought in contact with an internal body part, i.e. invasive · CPC title