Counter Electrode Replenishment for Long-Life Glucose Biosensors
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Solution Overview
Problem
Continuous glucose monitoring biosensors face limitations due to the rapid consumption of silver chloride at the counter electrode, leading to a short usage lifetime and increased implantation length, causing discomfort and infection risks for patients.
Innovation Solution
A method and device for a biosensor that includes a cyclic process of applying measurement and replenishment potentials to the counter electrode, allowing for the controlled consumption and replenishment of silver halide, thereby maintaining a stable silver halide level and reducing the size and implantation depth of the biosensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the counter electrode is designed with sufficient silver chloride capacity to maintain stable measurement for extended periods, then the usage lifetime of the biosensor is prolonged, but the dimension (length) of the counter electrode increases, causing deeper implantation and increased patient discomfort
Solution Approach 1:
The patent implements periodic switching between measurement mode and replenishment mode. During measurement mode, the working electrode measures glucose while the counter electrode consumes silver chloride. During replenishment mode, the polarity is reversed to regenerate silver chloride on the counter electrode. This periodic action allows the biosensor to maintain extended usage lifetime (14-16 days) without requiring a long counter electrode, as the silver chloride is continuously regenerated during replenishment periods.
Solution Approach 2:
The patent changes the operational parameters of the counter electrode by switching its role between consumption mode (during measurement) and regeneration mode (during replenishment). By applying different potentials and reversing polarity periodically, the silver chloride content on the counter electrode is dynamically maintained within an optimal range, allowing compact electrode dimensions while achieving extended usage lifetime.
2Ease of operation
If the counter electrode dimension is reduced to minimize implantation length and patient discomfort, then ease of operation is improved, but the silver chloride capacity is insufficient, leading to short usage lifetime
Solution Approach 1:
The periodic switching between measurement and replenishment modes enables a compact counter electrode to provide sufficient silver chloride capacity. The replenishment phase regenerates silver chloride that was consumed during measurement, effectively extending the functional capacity of a small-sized electrode without requiring deep implantation.
Solution Approach 2:
The counter electrode serves itself by regenerating its own silver chloride capacity through the replenishment mode. During replenishment, the polarity is reversed causing oxidation of silver to reform silver chloride on the counter electrode surface, eliminating the need for external replacement or large initial capacity.
3Object-affected harmful factors
If the counter electrode is made compact to reduce biological toxicity and implantation trauma, then object-affected harmful factors are reduced, but the silver chloride depletes quickly, causing measurement instability
Solution Approach 1:
The periodic replenishment mode prevents silver chloride depletion by regularly regenerating it on the counter electrode. This maintains measurement stability and reliability over extended periods while keeping the electrode compact, thereby reducing implantation trauma and biological toxicity associated with large electrode sizes.
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 extends the biosensor's usage lifetime, reduces biological toxicity, and minimizes patient discomfort by maintaining stable glucose monitoring with a compact sensor size.
Implementation Method 1
applying a replenishment potential difference across the counter electrode and the working electrode during a replenishment period so that the counter electrode has a higher voltage than that of the working electrode, causing a second oxidation reaction to occur to the silver on the counter electrode, so that the silver chloride gains a replenishment amount
Implementation Method 2
applying a measurement potential difference across the working electrode and the counter electrode so that the working electrode has a higher voltage than that of the counter electrode during a measurement period, causing a first oxidation reaction to occur on the working electrode having an electrochemical reaction with the chemical reagent and the analyte, thereby the working electrode outputs a physiological signal
Data Source
AI summary
A biosensor for measuring a physiological signal representative of a physiological parameter associated with an analyte is described. The biosensor includes a working electrode and a counter electrode. The counter electrode including a silver and a silver halide having an initial amount, wherein the initial amount is determined by the following steps of defining a required consumption range of the silver halide during at least one of the measurement periods performed by the biosensor; and determining the initial amount based on a sum of an upper limit of the required consumption range and a buffer amount, so that a required replenishment amount range of the silver halide during the replenishment period is controlled to be sufficient to maintain an amount of the silver halide within a safe storage range.