Calibration Factor Compensation for Continuous Glucose Sensors
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Solution Overview
Problem
Existing methods for compensating calibration factors in continuous glucose monitoring systems do not accurately consider real-time changes in sensor characteristics, leading to inaccurate blood glucose value calculations.
Innovation Solution
A method that calculates a calibration factor by obtaining a reference average value from biosignals measured over a specific time period after sensor insertion, and then determines an offset from the difference between this reference average value and a comparison average value, thereby compensating for sensor characteristic changes in real time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration factor is calculated using a fixed method without considering sensor characteristic changes, then the calculation process is simple, but the accuracy of blood glucose value measurements deteriorates over time as sensor characteristics change
Solution Approach 1:
The calibration factor calculation is made dynamic by continuously updating it based on the relationship between biosignal values and reference blood glucose values measured at different time points. The calibration factor is recalculated using the formula: calibration factor = (reference blood glucose value - offset) / biosignal value, where the offset is determined from the difference between calibration curve intercepts at different time points. This dynamic adjustment compensates for sensor characteristic changes and maintains measurement accuracy throughout the sensor's usage period.
Solution Approach 2:
The method changes the parameters used in calibration factor calculation by introducing time-dependent parameters. Instead of using a fixed calibration factor, the system calculates calibration factors at different time points (first time point, second time point) and uses the change in intercept values of calibration curves to determine an offset. This offset is then applied to adjust the calibration factor, effectively compensating for sensor drift and characteristic changes over time.
2Reliability
If sensor characteristics are not compensated for over time, then the system operation is simple, but the reliability of continuous glucose monitoring deteriorates due to sensor drift
Solution Approach 1:
The system implements feedback by continuously comparing biosignal values with reference blood glucose values (from fingerstick measurements) and using this information to update the calibration factor. The feedback loop calculates the offset based on the difference between calibration curves at different time points and applies this offset to compensate for sensor drift. This feedback mechanism ensures that the monitoring system adapts to sensor characteristic changes and maintains reliability throughout the monitoring period.
Solution Approach 2:
The method performs preliminary calibration actions by establishing calibration curves at a first time point and determining intercept values before the sensor is fully settled. The offset is calculated in advance based on the difference between intercepts at different time points, allowing the system to pre-compensate for expected sensor drift. This preliminary calibration approach enables the system to proactively address sensor characteristic changes rather than reactively correcting them.
3Measurement precision
If calibration is performed frequently to maintain accuracy, then measurement precision is improved, but the burden on the user and system complexity increases
Solution Approach 1:
The system employs periodic calibration actions by calculating calibration factors at specific time intervals (first time point, second time point) rather than continuously. The offset is determined periodically based on reference blood glucose values obtained at these discrete time points. This periodic approach balances the need for accuracy with user convenience, requiring calibration operations only at necessary intervals while maintaining measurement precision between calibration points.
Data Source
AI summary
The present invention relates to a method for compensating a calibration factor in a system for measuring continuous biometric information and, more particularly, to a method for compensating a calibration factor, wherein: an offset is obtained in consideration of the sensor characteristics that change over time of sensor use after a sensor is inserted into the body, thereby accurately compensating a calibration factor in consideration of the sensor characteristics that change in real time; and a reference average value is obtained from biosignals from a first time point to a second time point after a sensor is inserted, and an offset is obtained from the difference between the reference average value and a comparison average value that changes over time of sensor use, thereby obtaining an offset in an accurate and noise-resistant manner.