Micro Biosensor Electrode Cycling for Stable Long-Life Glucose Sensing
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Solution Overview
Problem
Existing continuous glucose monitoring (CGM) biosensors face limitations in usage lifetime due to silver chloride depletion, leading to unstable measurements and increased implantation length, which results in patient discomfort and infection risks.
Innovation Solution
A micro biosensor design with a four-electrode system that cyclically applies measurement and replenishment potentials to maintain silver halide levels within a safe range, allowing for uninterrupted glucose monitoring and reducing the size of the counter electrode, thereby minimizing implantation depth and pain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the counter electrode capacity is increased to prolong usage lifetime, then the biosensor can support continuous monitoring for longer periods, but the implantation length increases causing patient discomfort and infection risks
Solution Approach 1:
The patent applies periodic action by implementing cyclic potential switching between measurement mode and replenishment mode. The counter electrode alternates between consuming silver halide during measurement and regenerating silver halide during replenishment, enabling continuous operation without increasing implantation length. This periodic cycling allows the biosensor to maintain functionality for at least 14 days with a compact electrode length of not more than 10 mm.
2Duration of action of stationary object
If the counter electrode capacity is increased to prolong usage lifetime, then the biosensor can support continuous monitoring for longer periods, but the device size increases
Solution Approach 1:
The periodic cycling between measurement and replenishment modes enables the counter electrode to regenerate silver halide in situ, eliminating the need for large initial silver halide reserves. This reduces the counter electrode capacity requirement from 27.68 mC (without replenishment) to a much smaller capacity that supports at least 14 days of operation with cyclic regeneration, thereby miniaturizing the overall device size.
Solution Approach 2:
The replenishment mode enables the counter electrode to self-regenerate silver halide using the working electrode as a counter during the replenishment phase. This self-service mechanism eliminates the need for external replacement or large initial capacity, allowing the biosensor to maintain prolonged usage lifetime with a compact form factor suitable for subcutaneous implantation.
3Productivity
If silver halide is depleted during measurement, then the measurement function continues operating, but the reference voltage becomes unstable causing drifting problems
Solution Approach 1:
The patent implements periodic switching between measurement mode and replenishment mode to prevent silver halide depletion. During replenishment mode, the potential polarity is reversed to regenerate silver halide on the counter electrode, ensuring that silver halide content remains within a safe range throughout the measurement period. This periodic regeneration maintains reference voltage stability while ensuring continuous measurement capability for at least 14 days.
Solution Approach 2:
The control unit monitors the measurement current and determines when to switch between measurement and replenishment modes based on accumulated charge. This feedback mechanism ensures that silver halide is replenished before complete depletion occurs, maintaining reference voltage stability. The system calculates the required replenishment duration based on the measurement current, creating a closed-loop control that prevents drifting while ensuring continuous operation.
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
The solution extends the biosensor's usage lifetime, reduces biological toxicity, and miniaturizes the implantation end, providing more flexible and efficient operation while maintaining accurate glucose monitoring.
Implementation Method 1
applying a first measurement potential difference across the first working electrode and the first counter electrode so that the first working electrode has a higher voltage level than that of the first counter electrode during a first measurement period, for causing a first oxidation reaction to occur on the first working electrode having an electrochemical reaction with the chemical reagent and the analyte
Implementation Method 2
causing a first oxidation reaction to occur on the first working electrode having an electrochemical reaction with the chemical reagent and the analyte
Implementation Method 3
applying a first replenishment potential difference across the first counter electrode and one of the first and the second working electrodes during a first replenishment period so that the first counter electrode has a higher voltage level than that of the one of the first and the second working electrodes, for causing a second oxidation reaction to occur to the silver on the first counter electrode so that the silver halide gains a first replenishment amount
Data Source
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AI summary
The present invention provides a measuring method for prolonging a usage lifetime of a biosensor (400) to measure a physiological signal representative of a physiological parameter associated with an analyte in a biofluid. The biosensor (400) includes two working electrodes (420, 430) at least partially covered by a chemical reagent (460) and two counter electrodes (440, 450) having silver and a silver halide, and each silver halide has an initial amount. The measuring method includes cyclic steps of: applying a measurement voltage to drive one (420) of the two working electrodes (420, 430) at a measurement period to measure the physiological signal, thereby obtaining the physiological parameter, wherein the silver halide of one (420) of the two working electrodes (420, 430) is consumed by a consumption amount; stopping applying the measurement voltage; and applying a replenishment voltage to drive the consumed counter electrode (440) at a replenishment period to replenish the silver halide of a recharge amount to the consumed counter electrode (440), wherein: whenever the physiological parameter is obtained, a guarding value of a sum of the recharge amount and the initial amount subtracting the consumption amount is controlled within a range of the initial amount plus or minus a specific value.