Glucose Sensor EIS Diagnostics and Electrode Remediation

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Solution Overview

Problem

Current continuous glucose monitors face challenges with sensor stabilization time, inaccurate readings due to electrode hydration and pollution, and lack of automatic procedures for determining sensor functionality and pollution effects.

Innovation Solution

A diagnostic EIS procedure is performed to verify sensor functionality by calculating impedance values between electrodes and comparing them against thresholds, with remedial actions such as applying reversed DC voltage or DC voltage with AC signal to address pollution issues, and using EIS for initialization, hydration, and age detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a manual stabilization procedure is used, then the sensor can be stabilized, but the patient must wait three hours and bears the responsibility to remember to power on the sensor

Engineering Contradiction:
Improvesensor stabilizationVSAvoidstabilization time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The sensor system automatically performs stabilization and hydration procedures without requiring manual intervention from the patient. The control circuit detects sensor insertion, initiates stabilization sequences, and monitors sensor performance automatically, eliminating the need for patients to remember manual procedures while maintaining reliable sensor operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously monitors sensor impedance and glucose readings to detect stabilization status and pollution effects. When degradation is detected, the system automatically initiates remedial actions such as reversed DC voltage application or AC voltage pulses, creating a closed-loop feedback system that maintains sensor performance without manual intervention.

Inventive Principle:
Principle #23Feedback

2Loss of time

If the sensor is powered on immediately, then the response time is reduced, but the electrodes are not sufficiently hydrated resulting in inaccurate readings

Engineering Contradiction:
Improveresponse timeVSAvoidreading accuracy
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The control circuit automatically initiates a hydration sequence immediately upon detecting sensor insertion, applying voltage pulses to wet the electrodes before glucose measurement begins. This preliminary hydration action ensures accurate readings from the start without requiring manual waiting periods, as the system proactively prepares the sensor for optimal performance.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If no automatic pollution detection is used, then the device complexity is reduced, but the sensor accuracy deteriorates due to unaddressed pollution

Engineering Contradiction:
Improvedetection system complexityVSAvoidsensor accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system continuously monitors sensor impedance and glucose readings to detect pollution effects. When degradation is detected, the control circuit automatically initiates remedial actions such as applying reversed DC voltage or AC voltage pulses to remove pollutants from the electrode surface, maintaining sensor accuracy through automated closed-loop control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system detects pollution by monitoring changes in electrical impedance parameters and glucose reading patterns. When abnormal parameter changes indicate pollution, the system applies corrective voltage pulses that temporarily alter the electrode surface properties to remove contaminants, restoring normal sensor performance.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If manual hydration instruction is provided, then the patient can hydrate the sensor, but the patient bears responsibility and may forget

Engineering Contradiction:
Improvesensor hydrationVSAvoidhydration reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control circuit automatically detects when the sensor is inserted into the body and initiates the hydration sequence without requiring any manual action from the patient. The system monitors electrode impedance to determine when hydration is sufficient and when glucose measurements can begin, ensuring reliable hydration every time without placing responsibility on the patient.

Inventive Principle:
Principle #25Self-service

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 reduces sensor stabilization time, ensures accurate readings by maintaining electrode hydration and detecting pollution, and extends sensor life by identifying and addressing pollution effects, thereby improving overall monitoring efficiency.

Implementation Method 1

A diagnostic EIS procedure is performed during the life of a sensor to verify the sensor is functioning normally. The EIS procedure may be performed between at least two electrodes of the sensor, which calculates an impedance value between the electrodes

Methodology Applied
Scientific EffectElectrochemical impedance spectroscopy: Electrical Resistance

Implementation Method 2

The sensor remedial action is the application of a reversed DC voltage. In an embodiments, the sensor remedial action is the application of a reversed DC voltage coupled with an AC voltage

Methodology Applied
Scientific EffectElectrochemical cleaning: Electrolysis

Data Source

PatentEP2185923B1Method and system for remedying sensor malfunctions detected by electrochemical impedance spectroscopy
Publication Date: 2012.12.12 MEDTRONIC MINIMED INC
  • EP2185923B1 patent drawingFigure 1
  • EP2185923B1 patent drawingFigure 2(a)
  • EP2185923B1 patent drawingFigure 2(b)

AI summary

A method and system that enables a user to maintain a sensor in real time. The present invention involves performing a diagnostic Electrochemical Impedance Spectroscopy (EIS) procedure to measure sensor impedance value in order to determine if the sensor is operating at an optimal level. If the sensor is not operating at an optimal level, the present invention may further involve performing a sensor remedial action. The sensor remedial action involves reversing the DC voltage being applied between the working electrode and the reference electrode. The reversed DC voltage may be coupled with an AC voltage to extend its reach.