Optical Analyte Sensor Dynamic Calibration via Isosbestic Reference
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Solution Overview
Problem
Existing continuous glucose monitoring (CGM) devices face challenges with noisy optical intensity signals and initial calibration, requiring accurate and dynamic calibration to ensure precise glucose measurements, which is essential for effective diabetes management.
Innovation Solution
An optical analyte sensor system that emits light at specific frequencies to measure fluorescence signals at isosbestic frequencies, allowing for self-calibration and dynamic recalibration by determining analyte concentration based on intensity measurements, and includes a processor to correct for sensor drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorescence intensity measurement is used to determine glucose concentration, then continuous monitoring capability is achieved, but measurement precision deteriorates due to noisy optical signals
Solution Approach 1:
The patent introduces an isosbestic wavelength as an intermediary reference point that is insensitive to glucose concentration changes. By measuring fluorescence at both the analyte-sensitive wavelength and the isosbestic wavelength, the system creates a reference signal that mediates the noisy measurement process, allowing noise cancellation through ratio calculation.
Solution Approach 2:
The patent changes the measurement parameter from single-wavelength intensity to multi-wavelength ratio. By measuring fluorescence intensity at multiple wavelengths (including the isosbestic point) and calculating ratios, the system transforms the noisy single-parameter measurement into a more robust multi-parameter measurement that compensates for signal variability.
2Measurement precision
If initial calibration is performed to ensure accurate glucose measurements, then measurement precision improves, but device complexity increases due to calibration requirements
Solution Approach 1:
The patent enables the sensor to perform self-calibration by utilizing the isosbestic wavelength as an internal reference. The system automatically adjusts measurements based on the reference signal without requiring external calibration standards or manual intervention, making the calibration process self-contained and eliminating complex external calibration procedures.
Solution Approach 2:
The patent incorporates the isosbestic reference measurement into every measurement cycle, performing the reference action preliminarily before calculating the final glucose concentration. This preliminary reference measurement is always available to correct subsequent analyte-sensitive measurements, eliminating the need for separate calibration steps.
3Device complexity
If single wavelength fluorescence measurement is used, then device complexity is reduced, but measurement precision deteriorates due to sensor drift
Solution Approach 1:
The isosbestic wavelength serves as an intermediary reference that monitors changes in the optical system independent of glucose concentration. By comparing the analyte-sensitive wavelength measurement with the isosbestic reference measurement, the system detects and corrects for sensor drift, photobleaching, and other temporal variations without adding significant complexity.
Solution Approach 2:
The isosbestic wavelength measurement serves multiple functions simultaneously: it acts as a reference for noise cancellation, a indicator for sensor drift detection, and a basis for real-time calibration. This multi-functionality allows a single additional wavelength measurement to address multiple sources of measurement error.
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
The system provides robust and accurate glucose monitoring, enabling real-time calibration and reducing errors associated with sensor drift, thereby improving the reliability and precision of glucose level measurements.
Implementation Method 1
a light emitter for emitting light at a stimulation frequency upon the sample
Implementation Method 2
The glucose binding protein undergoes a conformational change in the presence of glucose, which affects the fluorescence intensity. Accordingly fluorescence emission spectra may be used to determine glucose concentration continuously
Data Source
AI summary
An optical analyte sensor and diabetes management system is provided. The sensor preferably includes a hydrogel matrix for receiving a sample containing an analyte at unknown concentration, a light emitter for emitting light at a stimulation frequency, a light receiver for receiving a fluorescence signal at a first isosbestic frequency, and at a second frequency, for measuring an intensity of the fluorescence signal and the first and second frequencies. A processor determines a concentration of the analyte based on the respective intensities.