Hygroscopic Hydrogel Reference Electrode for Implantable Sensors
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Solution Overview
Problem
Conventional reference electrodes face challenges such as potential instability due to changes in solution concentration, mechanical issues in scaled-down implantable sensor systems, and difficulties in sterilization, particularly for hydrogel-based systems, which can lead to dehydration and damage from high temperatures or toxic residue from gas sterilization.
Innovation Solution
An integrated reference electrode system using a hygroscopic hydrogel electrolyte contained in a porous framework, allowing for rehydration without compromising contact with the reference electrode, and an ion selective membrane that maintains stability and reduces the need for continuous moisture, facilitating efficient sterilization and reducing toxic residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid based electrolytes are used in conventional reference electrodes, then ionic contact is established, but manufacturing and mechanical challenges arise particularly when scaled down for implantable sensor systems
Solution Approach 1:
The patent transforms the electrolyte from liquid to hydrogel state, changing its physical parameters to eliminate mechanical instability while maintaining ionic conductivity. This phase transition allows the electrolyte to be contained within a porous framework without leakage, solving the mechanical challenges of scaled-down implantable systems.
Solution Approach 2:
The patent creates a composite structure combining hydrogel electrolyte with a porous framework. This composite material integrates the ionic conductivity of hydrogel with the mechanical stability of the porous framework, enabling reliable miniaturized reference electrodes for implantable applications.
2Reliability
If hydrogel based systems are subjected to autoclaving for sterilisation, then sterilisation is achieved, but the hydrogel degrades due to high temperatures
Solution Approach 1:
The patent performs sterilisation before hydrogel formation rather than after. By sterilizing the porous framework and components beforehand, the hydrogel can be subsequently introduced without requiring high-temperature autoclaving that would degrade its composition. This sequence reversal preserves hydrogel integrity while achieving sterilisation.
3Stability of the object's composition
If gas sterilisation is used, then sterilisation is achieved with less damage, but toxic compounds are left that require removal
Solution Approach 1:
The patent performs sterilisation before hydrogel formation, eliminating the need for subsequent toxic gas sterilisation. The pre-sterilized framework can accommodate the hydrogel without requiring additional sterilisation steps that would leave toxic residues, thus solving both structural integrity and harmful factor issues.
4Volume of moving object
If the reference electrode is scaled down, then implantable sensor systems are enabled, but stability is reduced due to limited amount of silver chloride
Solution Approach 1:
The patent uses a composite hydrogel-electrolyte system within a porous framework that maximizes the utilization of limited silver chloride material. The hydrogel matrix provides efficient ion transport pathways, ensuring that even small amounts of Ag/AgCl can maintain stable potential in miniaturized electrodes.
Solution Approach 2:
The porous framework increases the surface area to volume ratio, allowing maximum contact between the limited silver chloride and the hydrogel electrolyte. This enhanced interface efficiency maintains potential stability despite the reduced overall electrode volume required for implantable applications.
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 system provides a stable reference potential, mitigates issues of evaporation and dehydration, and allows for efficient sterilization, enhancing the integration of hydrogel electrolytes in implantable sensor systems while maintaining biocompatibility and reducing costs.
Implementation Method 1
epithelial interfaces absorb excess liquid and ionic species over time through osmotic differences
Implementation Method 2
Ionic contact between the reference electrode and a test solution is established by a porous ceramic frit or ion exchange membrane so as to complete the electrochemical cell
Data Source
AI summary
An integrated reference electrode for use in an electrochemical measurement system, comprising: a reference electrode in combination with a hygroscopic hydrogel electrolyte impregnated and contained in a porous framework, wherein the hygroscopic hydrogel electrolyte is adapted to contact the reference electrode when in a hydrated state. Also, an ion selective membrane with an aromatic epoxy polymer made from one or more monomers having at least one epoxide group, and a chloride salt or a silver—silver chloride physically trapped in the aromatic epoxy polymer. On contact with water the aromatic epoxy polymer forms a network of channels for ion exchange. The membrane may be used between an electrolyte and an external fluid environment; or the membrane may be coated upon the surface of a reference electrode.