Glucose Sensor Algorithm Correcting Temperature and pH Effects

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Solution Overview

Problem

Current methods for measuring glucose levels in diabetic patients are inaccurate and time-consuming, particularly when using whole blood tests, and plasma glucose measurements are not suitable for real-time monitoring due to complexity and delay in processing.

Innovation Solution

The use of a modified Michaelis-Menten equation to estimate analyte concentration, incorporating temperature and pH calibration data, with measurement devices that include analyte, temperature, and pH sensing elements to generate signals indicative of glucose concentration, allowing for real-time bioavailable glucose measurement in whole blood.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If whole blood glucose measurement is used, then measurement speed is improved, but measurement precision deteriorates due to red blood cell diffusion interference

Engineering Contradiction:
Improvemeasurement speedVSAvoidmeasurement precision
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by modifying the Michaelis-Menten equation to incorporate temperature and pH as additional parameters. The corrected glucose concentration is calculated using: Glucose_corrected = (Km × Signal) / (Vmax - Signal) × f(T, pH), where f(T, pH) is a correction factor based on temperature and pH measurements. This allows whole blood measurement to maintain both speed and precision by mathematically compensating for red blood cell diffusion effects.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If plasma glucose measurement is used, then measurement precision is improved, but measurement time increases due to separation and processing requirements

Engineering Contradiction:
Improvemeasurement precisionVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential correction factors (temperature and pH) from the complex plasma processing procedure. Instead of performing full plasma separation and multiple analytical steps, the device measures temperature and pH directly from whole blood and applies mathematical corrections to the glucose signal, achieving plasma-level precision without the time-consuming separation process.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/chemical plasma separation system with a mathematical correction system. Rather than physically separating plasma from blood cells using centrifugation or filtration, the device uses computational algorithms that adjust the whole blood glucose reading based on temperature and pH measurements, achieving equivalent precision without mechanical separation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If temperature and pH correction is applied, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements multi-functionality by using a single sensor platform that simultaneously measures glucose, temperature, and pH. The device integrates multiple sensing capabilities into one unified system, where the same sensor chip can detect all three parameters, and the processing unit performs multiple functions including signal acquisition, temperature compensation, pH correction, and glucose calculation in a single integrated workflow.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 accurate and immediate estimation of bioavailable glucose levels in whole blood, reducing the need for plasma separation and minimizing errors from red blood cell diffusion, thus enabling precise insulin dosing.

Implementation Method 1

These include the measurement of the current produced by glucose oxidation

Methodology Applied
Scientific EffectGlucose oxidation: Oxidation

Implementation Method 2

The sensor also measures temperature

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 3

The detected signal is transformed by a Michaelis-Menton like equation

Methodology Applied
Scientific EffectMichaelis-Menten kinetics:

Data Source

PatentEP2545373B1Measuring analyte concentration incorporating temperature and ph correction
Publication Date: 2022.08.24 MEDTRONIC MINIMED INC
  • EP2545373B1 patent drawingFigure 1A
  • EP2545373B1 patent drawingFigure 1B
  • EP2545373B1 patent drawingFigure 1C

AI summary

Disclosed herein are methods of estimating an analyte concentration which include generating a signal indicative of the analyte concentration, generating a signal indicative of a temperature, generating a signal indicative of a pH, and transforming the signal indicative of the analyte concentration utilizing an equation of the form of a modified Michaelis-Menten equation depending on Michaelis-Menten parameters, wherein values of the Michaelis-Menten parameters are set based upon data which includes temperature and pH calibration parameters, the signal indicative of a temperature, and the signal indicative of a pH. Also disclosed herein are measurement devices which employ the aforementioned methods.