EIS Diagnostics for Redundant Glucose Sensor Electrodes
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Solution Overview
Problem
Current continuous glucose monitoring systems face issues such as prolonged sensor stabilization times, inaccurate readings due to insufficient electrode hydration, unreliable operation beyond the specified life, lack of real-time diagnostics for sensor health, and reliance on finger sticks for calibration, along with limited effectiveness in detecting interferents and managing redundant electrodes.
Innovation Solution
Employing electrochemical impedance spectroscopy (EIS) for real-time sensor diagnostics, including methods for electrode characterization, contaminant detection, and fusion algorithms to calculate a fused sensor glucose value, manage redundant electrodes, and perform sensor calibration, using Application Specific Integrated Circuits (ASICs) for sensor electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a continuous glucose sensor is first inserted into a patient's skin or subcutaneous layer, then the sensor must wait a certain amount of time (3 hours) to stabilize before providing accurate readings, but this prolonged stabilization time causes patient inconvenience and may lead to non-utilization of the system
Solution Approach 1:
The patent applies preliminary action by performing electrode characterization and hydration assessment using electrochemical impedance spectroscopy (EIS) before the sensor is fully stabilized. The system pre-evaluates electrode health metrics (such as charge transfer resistance and double-layer capacitance) during the stabilization period, allowing the sensor to provide accurate readings sooner by identifying when electrodes are sufficiently hydrated without requiring the full 3-hour wait.
Solution Approach 2:
The patent implements feedback by continuously monitoring EIS parameters during sensor operation and using this information to determine when the sensor is ready for accurate measurements. The system provides real-time feedback on electrode hydration status and stabilization progress, enabling dynamic adjustment of the measurement timeline based on actual sensor conditions rather than relying on fixed time delays.
2Reliability
If electrochemical impedance spectroscopy (EIS) procedures are performed frequently for real-time sensor diagnostics and electrode characterization, then sensor health monitoring and contaminant detection are improved, but power consumption and device complexity increase
Solution Approach 1:
The patent applies universality by designing the EIS diagnostic system to perform multiple functions simultaneously: electrode characterization, contaminant detection, hydration assessment, and stabilization monitoring. A single EIS measurement sequence provides information for all these purposes, eliminating the need for separate diagnostic systems and reducing overall device complexity while maintaining comprehensive sensor health monitoring.
Solution Approach 2:
The patent uses parameter changes by varying EIS measurement frequencies and amplitudes based on sensor operational stage and detected conditions. The system adjusts diagnostic parameters dynamically - using different frequency ranges during initial characterization versus ongoing monitoring, and modifying measurement intensity based on sensor health status - thereby optimizing the balance between diagnostic reliability and power consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid sensor stabilization, ensures accurate readings by monitoring electrode health, extends sensor life, reduces the need for finger sticks, and enhances the detection of interferents, thereby improving the reliability and efficiency of glucose monitoring.
Implementation Method 1
performing a first electrochemical impedance spectroscopy (EIS) procedure to generate a first set of impedance-related data for the at least one working electrode
Implementation Method 2
obtain a first impedance magnitude and a first phase for the working electrode
Implementation Method 3
measuring a current between the working electrode and the counter electrode in response to applying a voltage between the working electrode and the counter electrode
Data Source
AI summary
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.