Predictive Calibration for Glucose Sensor Drift

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Solution Overview

Problem

Continuous glucose monitors (CGMs) experience sensor drift over time, leading to inaccurate blood glucose level estimates, necessitating frequent calibration to maintain accuracy, which can be inconvenient and result in improper insulin dosages.

Innovation Solution

A portable medical monitor system generates a predictive calibration curve based on at least two data values, using a transformation function to produce more accurate analyte level estimates, reducing the need for frequent calibration and improving insulin delivery accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequent calibration is performed to maintain accuracy, then measurement precision is improved, but ease of operation deteriorates

Engineering Contradiction:
Improveblood glucose level estimation accuracyVSAvoidcalibration convenience
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs preliminary calibration actions by generating predictive calibration curves that anticipate future sensor drift patterns. Instead of waiting for accuracy to degrade and then calibrating, the system proactively creates calibration curves for future time points based on historical drift data, thereby maintaining accuracy without requiring frequent manual calibration operations from the user.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The calibration system performs self-service by automatically generating predictive calibration curves using the sensor's own historical calibration data and observed drift patterns. The system uses its accumulated data to self-correct and maintain accuracy without requiring external intervention or manual calibration inputs from the user, thereby improving ease of operation while maintaining measurement precision.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If sensor operation duration is extended to reduce calibration frequency, then ease of operation is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvecalibration frequencyVSAvoidblood glucose level estimation accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system extends sensor operation duration by performing preliminary actions - generating predictive calibration curves in advance for future time points. This allows the sensor to maintain accuracy over extended periods without calibration because the system has already prepared calibration data that accounts for anticipated drift, thereby simultaneously improving ease of operation and maintaining measurement precision.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The calibration system is made dynamic by continuously generating updated predictive calibration curves as the sensor operates. Instead of using a static calibration curve throughout the sensor's lifespan, the system dynamically creates new calibration curves based on accumulating drift data, allowing the calibration to adapt to changing sensor conditions while maintaining accuracy over extended operation periods.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If predictive calibration curves are generated to reduce calibration frequency, then ease of operation is improved, but device complexity increases

Engineering Contradiction:
Improvecalibration burdenVSAvoidcalibration processing complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The system handles the increased complexity through self-service - automatically performing all the complex calculations and data processing required for predictive calibration curve generation using the sensor's own historical data. This automation conceals the complexity from the user, maintaining ease of operation while the system internally manages the sophisticated calibration algorithms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The predictive calibration system uses feedback from historical calibration data and observed sensor drift patterns to continuously improve its calibration curve predictions. By analyzing past performance and feeding this information back into the calibration algorithm, the system can generate more accurate predictive curves with refined processing, managing complexity through intelligent feedback-based optimization rather than brute-force computational approaches.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS9486171B2Predictive calibration
Publication Date: 2016.11.08 TANDEM DIABETES CARE INC
  • US9486171B2 patent drawing
  • US9486171B2 patent drawing
  • US9486171B2 patent drawing

AI summary

A portable medical monitor system generates a current calibration curve for generating the estimate of the level of an analyte, such as glucose, being monitored. The current calibration curve is based on at least two measured data values of the level being monitored. The system determines a transformation function based on the calibration curve and at least one preceding calibration curve such that the transformation function produces a predictive calibration curve, and generates an estimated level value of the level being monitored, based on sensor output from a sensor associated with the portable medical monitor system, in accordance with the predictive calibration curve.