Application of electrochemical impedance spectroscopy in sensor systems, devices, and related methods
First Claim
1. A method of calibrating a sensor during a period of sensor transition, the method comprising:
- defining an electrochemical impedance spectroscopy (EIS)-based sensor status vector (V) for each one of a plurality of sensor current (Isig)-blood glucose (BG) pairs;
defining an Isig buffer to store Isig values of said plurality of Isig-BG pairs;
defining an BG buffer to store BG values of said plurality of Isig-BG pairs;
monitoring the status vectors for the plurality of Isig-BG pairs over time;
detecting when there is a difference between a first status vector for a first Isig-BG pair and a subsequent status vector for a subsequent Isig-BG pair;
if a magnitude of said difference is smaller than a predetermined threshold, calibrating said sensor based on values of said Isig-BG pairs from a first set of Isig and BG buffers; and
if the magnitude of said difference is larger than a predetermined threshold, calibrating said sensor based on values of said Isig-BG pairs from a second set of Isig and BG buffers, wherein said second set of Isig and BG buffers contains at least the values of Isig and BG from said subsequent Isig-BG pair.
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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.
115 Citations
9 Claims
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1. A method of calibrating a sensor during a period of sensor transition, the method comprising:
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defining an electrochemical impedance spectroscopy (EIS)-based sensor status vector (V) for each one of a plurality of sensor current (Isig)-blood glucose (BG) pairs; defining an Isig buffer to store Isig values of said plurality of Isig-BG pairs; defining an BG buffer to store BG values of said plurality of Isig-BG pairs; monitoring the status vectors for the plurality of Isig-BG pairs over time; detecting when there is a difference between a first status vector for a first Isig-BG pair and a subsequent status vector for a subsequent Isig-BG pair; if a magnitude of said difference is smaller than a predetermined threshold, calibrating said sensor based on values of said Isig-BG pairs from a first set of Isig and BG buffers; and if the magnitude of said difference is larger than a predetermined threshold, calibrating said sensor based on values of said Isig-BG pairs from a second set of Isig and BG buffers, wherein said second set of Isig and BG buffers contains at least the values of Isig and BG from said subsequent Isig-BG pair. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification