EIS Sensor Calibration for Glucose Electrode Reliability
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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 sensor diagnostics, and reliance on finger sticks for calibration, along with limited capabilities in managing redundant electrodes and detecting interferents.
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 detect interferents, using ASICs for implementing these functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional voltage application methods are used for sensor stabilization, then the sensor can be activated, but the stabilization time is prolonged (3-5 hours)
Solution Approach 1:
The patent applies periodic action by using alternating high and low voltage pulses in a cyclic manner during the stabilization process. The controller applies a high voltage pulse for a first time period, then a low voltage pulse for a second time period, repeating this cycle for multiple iterations. This periodic voltage application significantly reduces stabilization time from 3-5 hours to approximately 15-30 minutes while maintaining reading accuracy.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting voltage magnitude and application time based on sensor state. The controller varies voltage between high and low levels, and adjusts the duration of each pulse, transitioning from initial high voltage to stabilize the sensor, then to lower voltage for maintenance. This dynamic parameter adjustment accelerates stabilization while preserving measurement reliability.
2Loss of time
If the sensor is powered on immediately after insertion, then the response time is reduced, but the electrode hydration is insufficient leading to inaccurate readings
Solution Approach 1:
The patent applies preliminary action by performing voltage pulse stabilization and electrode hydration before the sensor is activated for glucose measurements. The controller executes multiple high-low voltage pulse cycles during an initialization period, ensuring the electrode is sufficiently hydrated and stabilized before beginning glucose readings. This preliminary preparation eliminates the need for extended delays while ensuring measurement accuracy.
3Ease of operation
If manual monitoring of sensor hydration and stabilization is required, then the patient has control, but the process is inconvenient and error-prone
Solution Approach 1:
The patent applies self-service by enabling the sensor system to automatically monitor and manage its own stabilization and hydration status without patient intervention. The controller continuously monitors sensor impedance and voltage responses, automatically adjusting voltage pulse parameters and determining when stabilization is complete. The system self-regulates the entire process, eliminating manual monitoring requirements and improving patient convenience.
Solution Approach 2:
The patent applies feedback by implementing continuous monitoring of sensor electrical characteristics during voltage pulse application. The controller measures impedance and current responses, uses this feedback to determine when stabilization criteria are met, and automatically adjusts or terminates the stabilization process. This closed-loop control eliminates manual monitoring while ensuring proper sensor preparation.
4Reliability
If redundant electrodes are added to the sensor, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by treating each redundant electrode as an independent sensing unit with its own dedicated processing path. The controller individually monitors and processes signals from multiple electrodes, allowing selective use of healthy electrodes while isolating faulty ones. This segmented approach maintains reliability through redundancy while managing complexity through modular, independent electrode processing.
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
Enhances sensor stability and accuracy by reducing stabilization time, ensuring reliable operation, minimizing the need for finger sticks, and providing real-time monitoring of sensor health and interferent detection, 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
Data Source
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AI summary
A method provides for calibrating a sensor, the method comprises performing an electrochemical impedance spectroscopy (EIS) procedure for a working electrode of a sensor to obtain values of at least one impedance-based parameter for said working electrode; performing a bound check on said values of the at least one impedance-based parameter to determine whether said at least one impedance-based parameter is in-bounds and, based on said bound check, calculating a reliability-index value for said working electrode; and determining, based on the value of said reliability index, whether calibration should be performed, or whether calibration should be delayed until a later time.