Glucose Sensor Moving Horizon Estimation
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Solution Overview
Problem
Current continuous glucose monitoring systems face inaccuracies due to the time delay and muffled response between blood glucose levels and interstitial tissue glucose levels, leading to calibration challenges and inaccuracies in determining blood glucose concentrations.
Innovation Solution
A process using a sensor device to measure tissue glucose levels over time, correlating these measurements with a sensor model and state transition model to estimate blood glucose levels through the Moving Horizon Estimation Method, accounting for measurement and process noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interstitial tissue glucose concentration is measured continuously, then measurement frequency is significantly increased compared to manual self-monitoring, but the determination accuracy of blood glucose concentration deteriorates due to time delay and diffusion muffling
Solution Approach 1:
The patent applies preliminary action by measuring interstitial tissue glucose concentration continuously in advance before blood glucose levels change significantly. The sensor device continuously monitors IG levels and feeds this data to the evaluating device, which then predicts current blood glucose concentration BG based on the accumulated tissue glucose data, allowing accurate determination without waiting for blood glucose to actually change
Solution Approach 2:
The patent replaces the mechanical/biological diffusion process with an information processing system. Instead of relying on the natural diffusion of glucose from blood to tissue (which causes delay), the system uses sensor measurements of interstitial glucose and mathematical evaluation algorithms to infer blood glucose levels, substituting the physical diffusion mechanism with an informational evaluation mechanism
2Ease of manufacture
If calibration is performed using manual blood glucose determination, then the CGM system can be calibrated, but significant inaccuracies occur due to the diffusion delay between blood and tissue glucose levels
Solution Approach 1:
The patent replaces the manual finger-prick blood sampling method with a continuous interstitial tissue glucose sensor. The sensor device continuously measures IG levels in the tissue, and the evaluating device processes this data to determine BG levels, eliminating the need for manual calibration and the associated timing issues with blood-to-tissue diffusion
Solution Approach 2:
The patent implements continuous measurement of interstitial tissue glucose concentration, replacing discrete manual calibration points with an ongoing continuous monitoring process. The sensor device continuously feeds IG data to the evaluating device, which continuously updates BG determinations, ensuring accurate blood glucose levels are available at all times without interruption or manual intervention
3Measurement precision
If complex models are used to compensate for diffusion delay and muffling, then blood glucose determination accuracy improves, but computational resources and energy consumption increase
Solution Approach 1:
The patent changes the measured parameter from direct blood glucose concentration to interstitial tissue glucose concentration, which can be measured continuously with lower computational overhead. The evaluating device then uses this continuously available tissue glucose data to infer blood glucose levels through mathematical relationships, achieving accurate BG determination while maintaining reasonable computational requirements
Solution Approach 2:
The system uses the naturally occurring interstitial tissue glucose as a self-providing indicator of blood glucose levels. The tissue glucose concentration serves its own function as a proxy measurement, eliminating the need for complex external calibration procedures or additional sensors, thereby reducing computational and energy requirements while maintaining accuracy
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
This approach provides more accurate and flexible determination of blood glucose levels, improving both current and retrospective glucose concentration estimates while reducing computational resources and energy consumption.
Implementation Method 1
This deviation is caused by a diffusion process in the tissue surrounding the blood, so that the IG level is delayed in time and follows the BG level in a muffled manner
Data Source
AI summary
The invention relates to a method in particular for continuously determining a current glucose value in a transported fluid, in particular blood, of an organism, having the steps of: a) ascertaining a series of measurements, comprising at least two measurement values separated by time intervals, for a tissue glucose value in the tissue surrounding the transported fluid using a sensor device, b) ascertaining the tissue glucose value using the ascertained series of measurements on the basis of a sensor model, wherein measurement values of the sensor device are assigned to tissue glucose values while taking into consideration measurement noise using a sensor model, c) providing a state transition model, the ascertained tissue glucose values being assigned at least one glucose value in the transported fluid using the state transition model while taking into consideration process noise, and d) ascertaining the current glucose value on the basis of the provided state transition model and the ascertained tissue glucose value. At least step d), in particular steps b)-d), is carried out using at least one moving horizon estimation method.