Application of electrochemical impedance spectroscopy in sensor systems, devices, and related methods
First Claim
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.
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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.
120 Citations
12 Claims
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1. A method for real-time detection of low start-up for a working electrode of a glucose sensor, the method comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for real-time detection of low start-up for a plurality of working electrodes of a glucose sensor, the method comprising:
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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. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification