APPLICATION OF ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY IN SENSOR SYSTEMS, DEVICES, AND RELATED METHODS
First Claim
1. A method of calculating a single, fused sensor glucose value based on respective glucose measurement signals of a plurality of redundant sensing electrodes, comprising:
- performing respective electrochemical impedance spectroscopy (EIS) procedures for each of the plurality of redundant sensing electrodes to obtain values of at least one impedance-based parameter for each said sensing electrode;
measuring the electrode current (Isig) for each of the plurality of redundant sensing electrodes;
independently calibrating each of the measured Isigs to obtain respective calibrated sensor glucose values;
performing a bound check and a noise check on said measured Isig and said values of the at least one impedance-based parameter and assigning a bound-check reliability index and a noise-check reliability index to each said sensing electrode;
performing signal-dip analysis based on one or more of said at least one impedance-based parameter and assigning a dip reliability index to each said sensing electrode;
performing sensitivity-loss analysis based on one or more of said at least one impedance-based parameter and assigning a sensitivity-loss index to each said sensing electrode;
for each of the plurality of electrodes, calculating a total reliability index based on said electrode'"'"'s bound-check reliability index, noise-check reliability index, dip reliability index, and sensitivity-loss reliability index;
for each of the plurality of electrodes, calculating a weight based on said electrode'"'"'s total reliability index; and
calculating said single, fused sensor glucose value based on the respective weights and calibrated sensor glucose values of each of the plurality of redundant sensing electrodes.
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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.
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Citations
14 Claims
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1. A method of calculating a single, fused sensor glucose value based on respective glucose measurement signals of a plurality of redundant sensing electrodes, comprising:
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performing respective electrochemical impedance spectroscopy (EIS) procedures for each of the plurality of redundant sensing electrodes to obtain values of at least one impedance-based parameter for each said sensing electrode; measuring the electrode current (Isig) for each of the plurality of redundant sensing electrodes; independently calibrating each of the measured Isigs to obtain respective calibrated sensor glucose values; performing a bound check and a noise check on said measured Isig and said values of the at least one impedance-based parameter and assigning a bound-check reliability index and a noise-check reliability index to each said sensing electrode; performing signal-dip analysis based on one or more of said at least one impedance-based parameter and assigning a dip reliability index to each said sensing electrode; performing sensitivity-loss analysis based on one or more of said at least one impedance-based parameter and assigning a sensitivity-loss index to each said sensing electrode; for each of the plurality of electrodes, calculating a total reliability index based on said electrode'"'"'s bound-check reliability index, noise-check reliability index, dip reliability index, and sensitivity-loss reliability index; for each of the plurality of electrodes, calculating a weight based on said electrode'"'"'s total reliability index; and calculating said single, fused sensor glucose value based on the respective weights and calibrated sensor glucose values of each of the plurality of redundant sensing electrodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification