Glucose Sensor Self-Calibration Using EIS for Fingerstick-Free Accuracy
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Solution Overview
Problem
Current continuous glucose monitoring systems require frequent and inconvenient fingerstick calibrations due to inherent inaccuracies and susceptibility to user error, and lack reliable methods for sensor diagnostics and self-calibration.
Innovation Solution
Implementing Electrochemical Impedance Spectroscopy (EIS) procedures with microcontroller-based glucose sensors to generate predictive models, calculate and fuse sensor glucose values, apply calibration factors, and perform error detection diagnostics for accurate and calibration-free glucose readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fingerstick calibration is performed frequently to improve measurement precision, then glucose reading accuracy is improved, but user discomfort and operation complexity increase
Solution Approach 1:
The sensor performs self-calibration using internal reference measurements and auto-calibration algorithms, eliminating the need for users to perform manual fingerstick calibrations. The system automatically adjusts calibration factors based on measured reference values, allowing the sensor to service itself without user intervention.
Solution Approach 2:
The patent replaces the mechanical fingerstick calibration process with an electrical/optical measurement system that uses internal reference electrodes and optical sensors to perform calibration automatically. This substitution eliminates the need for physical blood sampling and manual calibration operations.
2Measurement precision
If fingerstick calibration is performed frequently to improve measurement precision, then glucose reading accuracy is improved, but time consumption increases
Solution Approach 1:
The sensor performs preliminary calibration measurements using internal reference electrodes and stored calibration data before actual glucose measurements are needed. This preliminary calibration establishes baseline values that enable rapid subsequent measurements without requiring frequent time-consuming fingersticks.
Solution Approach 2:
The system maintains continuous calibration through ongoing internal reference measurements and automatic calibration updates, eliminating the discontinuous, periodic nature of manual fingerstick calibration. This continuous calibration process ensures accuracy is maintained without intermittent time losses.
3Measurement precision
If manual calibration procedures are used to improve measurement precision, then calibration accuracy can be maintained, but device complexity and user error susceptibility increase
Solution Approach 1:
The patent merges the calibration reference system into the sensor itself by integrating internal reference electrodes and calibration algorithms within the sensor assembly. This consolidation eliminates the need for separate external calibration devices and procedures, reducing overall system complexity while maintaining calibration accuracy.
Solution Approach 2:
The sensor performs self-calibration using internal reference measurements and auto-calibration algorithms, eliminating the need for users to perform manual calibration operations. The system automatically manages calibration factors and adjusts based on measured reference values, reducing both complexity and user error susceptibility.
4Measurement precision
If external calibration devices are used to improve measurement precision, then calibration accuracy is improved, but cost and user burden increase
Solution Approach 1:
The patent merges the calibration reference system into the sensor itself by integrating internal reference electrodes and calibration algorithms within the sensor assembly. This consolidation eliminates the need for separate external calibration devices, reducing cost and user burden while maintaining calibration accuracy.
Solution Approach 2:
The sensor performs self-calibration using internal reference measurements and auto-calibration algorithms, eliminating the need for users to obtain and use external calibration devices. The system automatically manages its own calibration, reducing both user burden and the need for additional external components.
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
Reduces the need for fingerstick calibrations and enhances sensor reliability by providing accurate, real-time glucose measurements through self-calibration and diagnostics, minimizing user discomfort and improving system precision.
Implementation Method 1
periodically measuring, by the physical sensor electronics, electrode current (Isig) signals for the working electrode
Implementation Method 2
performing, by the microcontroller, an Electrochemical Impedance Spectroscopy (EIS) procedure to generate EIS-related data for the working electrode
Data Source
AI summary
A continuous glucose monitoring system may utilize externally sourced information regarding the physiological state and ambient environment of its user for externally calibrating sensor glucose measurements. Externally sourced factory calibration information may be utilized, where the information is generated by comparing metrics obtained from the data used to generate the sensor's glucose sensing algorithm to similar data obtained from each batch of sensors to be used with the algorithm in the future. The output sensor glucose value of a glucose sensor may also be estimated by analytically optimizing input sensor signals to accurately correct for changes in sensitivity, run-in time, glucose current dips, and other variable sensor wear effects. Correction actors, fusion algorithms, EIS, and advanced ASICs may be used to implement the foregoing, thereby achieving the goal of improved accuracy and reliability without the need for blood-glucose calibration, and providing a calibration-free, or near calibration-free, sensor.