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 (Isiq) for each of the plurality of redundant sensing electrodes;
calibrating each of the measured Isiqs by using a blood glucose (BG) value to obtain respective calibrated sensor glucose values;
calculating a plurality of reliability indices for each said sensing electrode based on said values of the at least one impedance-based parameter, said plurality of reliability indices including a dip reliability index that is calculated by;
calculating a first similarity index to determine an amount of divergence between respective Isigs of at least a first one and a second one of said plurality of redundant sensing electrodes;
calculating a second similarity index to determine an amount of divergence between respective values of the at least one impedance-based parameter for said at least first one and second one of said plurality of redundant sensing electrodes;
mapping said first similarity index to said second similarity index; and
mapping said second similarity index to said first similarity index; and
calculating said single, fused sensor glucose value based on said plurality of reliability indices 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
20 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 (Isiq) for each of the plurality of redundant sensing electrodes; calibrating each of the measured Isiqs by using a blood glucose (BG) value to obtain respective calibrated sensor glucose values; calculating a plurality of reliability indices for each said sensing electrode based on said values of the at least one impedance-based parameter, said plurality of reliability indices including a dip reliability index that is calculated by; calculating a first similarity index to determine an amount of divergence between respective Isigs of at least a first one and a second one of said plurality of redundant sensing electrodes; calculating a second similarity index to determine an amount of divergence between respective values of the at least one impedance-based parameter for said at least first one and second one of said plurality of redundant sensing electrodes; mapping said first similarity index to said second similarity index; and mapping said second similarity index to said first similarity index; and calculating said single, fused sensor glucose value based on said plurality of reliability indices 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, 15, 16, 17, 18, 19, 20)
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Specification