Implantable Micro-Biosensor Electrodes for Interference Removal
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Solution Overview
Problem
Existing implantable glucose monitoring systems face challenges in accurately measuring glucose concentrations due to interference from substances like ascorbic acid, acetaminophen, and uric acid, and have limited service life due to silver chloride consumption, leading to increased wound size and infection risk during implantation.
Innovation Solution
An implantable micro-biosensor with multiple working electrodes and a counter electrode using silver/silver halide to measure glucose concentrations while consuming interfering substances and regenerating silver halide, ensuring accurate measurement and extended service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a polymer membrane is provided to filter out interfering substances, then measurement accuracy is improved, but it remains difficult to filter out the interfering substances completely
Solution Approach 1:
The patent divides the single filtering function into multiple specialized electrodes, each targeting specific interfering substances. The first working electrode measures glucose, while the second and third working electrodes specifically target ascorbic acid and acetaminophen respectively, eliminating interference through segmented functional specialization rather than a single membrane filter.
Solution Approach 2:
The patent introduces enzyme mediators (glucose oxidase, ascorbic acid oxidase, acetaminophen oxidase) as intermediary substances that catalyze specific reactions between the target analytes and electrodes. These enzyme-coated electrodes act as selective intermediaries that enable accurate measurement by converting interfering substances into detectable signals that can be mathematically subtracted.
2Stability of the object's composition
If silver/silver chloride is used as the counter electrode material, then stable sensing potential is obtained, but silver chloride is consumed by reduction leading to reference potential shift and limited service life
Solution Approach 1:
The patent implements a regeneration mechanism where the counter electrode periodically recovers its silver chloride coating through application of a reverse potential. During regeneration mode, the counter electrode undergoes oxidation that reforms silver chloride from dissolved silver ions, thereby recovering the consumed material and restoring the electrode's functionality and stable reference potential.
Solution Approach 2:
The patent employs periodic switching between measurement mode and regeneration mode. During regeneration mode, a reverse potential is applied to the counter electrode for a specific duration to restore silver chloride coating. This periodic action maintains long-term stability by replenishing consumed silver chloride before complete depletion occurs, extending the biosensor's service life.
3Duration of action of stationary object
If the counter electrode length is increased to greater than 10 mm to extend service life, then silver chloride consumption capacity is sufficient, but the biosensor requires oblique angle implantation resulting in larger wound, higher infection risk, and more pronounced pain
Solution Approach 1:
The patent changes the operational parameters of the counter electrode by applying periodic reverse potentials during regeneration mode. This parameter change enables the electrode to recover its silver chloride coating in situ, thereby maintaining sufficient service life without requiring increased physical length. The functional extension through parameter control replaces the structural extension approach.
4Measurement precision
If multiple working electrodes are used to read signals and process them to accurately obtain physiological parameters, then measurement accuracy is improved, but the process becomes very complicated
Solution Approach 1:
The patent changes the measurement parameters by applying distinct potentials to different working electrodes at different time intervals. The first working electrode measures glucose at one potential, while the second and third working electrodes measure ascorbic acid and acetaminophen at different potentials. This parameter-based differentiation simplifies the system by using temporal and potential variation rather than complex spatial arrangements.
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 micro-biosensor effectively reduces interference and extends service life by using multiple electrodes and a counter electrode to consume and regenerate silver halide, providing accurate glucose monitoring with reduced implantation pain and wound size.
Implementation Method 1
glucose is subjected to a catalysis reaction with glucose oxidase (GOx) to produce gluconolactone and a reduced glucose oxidase, followed by an electron transfer reaction between the reduced glucose oxidase and oxygen in a biological fluid of the body to produce hydrogen peroxide (H2O2) as a byproduct. The glucose concentration is then derived from an oxidation reaction of the byproduct H2O2.
Implementation Method 2
the second sensing section is driven by a second potential difference to form an interference-eliminating region that is in touch with a surrounding of the first sensing section and at least partially overlaps with the measuring region, so as to consume an interfering substance in the body
Implementation Method 3
the at least one counter electrode is driven to regenerate silver halide
Data Source
AI summary
An implantable micro-biosensor includes a substrate, a first working electrode, at least one second working electrode, and at least one counter electrode. The first working electrode includes a first sensing section driven by a first potential difference to measure a physiological signal. The second working electrode includes a second sensing section driven by a second potential difference to consume an interfering substance. The counter electrode cooperates with the first working electrode to measure the physiological signal, cooperates with the second working electrode to consume the interfering substance, and selectively cooperates with the first or second working electrode to regenerate silver halide.