Bio-Electrode Ionic Resin Composition for Stable Skin Contact
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Solution Overview
Problem
Existing bio-electrodes for wearable devices face challenges in maintaining electric conductivity and biocompatibility over long-term use, causing skin allergies and peeling issues, while also being costly and uncomfortable due to water loss or acidity.
Innovation Solution
A bio-electrode composition using an ionic resin with ammonium, lithium, or potassium salts of trissulfonium methide, combined with silicone or acrylic-based adhesives, and carbon or metal powders to enhance conductivity, biocompatibility, and adhesiveness, ensuring stability and comfort during long-term use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble gel containing water and electrolyte is used as electro-conductive paste, then electric conductivity is improved, but electric conductivity is lost when water dries out
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid (water-based gel) to solid (ionic liquid), and further to a polymer-bound ionic liquid state. This parameter change eliminates the drying issue while maintaining ionic conductivity, as the ionic liquid remains stable in solid form and can be retained within the polymer structure indefinitely.
Solution Approach 2:
The patent creates a composite material system combining polymer matrix with ionic liquid components. The polymer provides structural stability and water retention, while the ionic liquid provides sustained ionic conductivity. This composite approach allows the electrode to maintain both mechanical integrity and electrical function over long periods.
2Reliability
If metal nanowire is used as electrode material, then electric conductivity is improved, but skin allergies are caused due to sharp tips
Solution Approach 1:
The patent changes the morphology parameter of the conductive material from sharp nanowires to spherical or irregular-shaped ionic liquid particles dispersed in polymer. This shape modification eliminates the sharp tips that cause skin penetration and allergies, while the high surface area of the particles maintains effective ionic conductivity.
Solution Approach 2:
The patent introduces a polymer matrix as an intermediary between the conductive ionic liquid particles and the skin. The polymer encapsulates the ionic liquid particles, preventing direct contact with skin while allowing ionic conduction through the material, thus eliminating allergic reactions while maintaining conductivity.
3Reliability
If noble metal is used as bio-electrode, then electric conductivity is improved, but ion conversion efficiency is reduced due to difficulty in ionization
Solution Approach 1:
The patent replaces noble metals with ionic liquid-based materials that copy the essential function of ion conduction without the drawbacks of metal ionization difficulties. The ionic liquid inherently contains mobile ions that can easily exchange with skin ions, replicating the desired electrochemical function with superior ion conversion efficiency.
4Reliability
If ionic liquid with small molecular weight is added to battery, then electric conductivity is improved, but skin problems occur due to extraction and penetration
Solution Approach 1:
The patent embeds the ionic liquid molecules within the polymer matrix structure, creating a nested configuration where the ionic liquid is contained within the polymer network. This nesting prevents the ionic liquid from being extracted by sweat or penetrating the skin, while still allowing ionic conduction through the material bulk.
Solution Approach 2:
The patent uses the polymer matrix as a flexible shell that encapsulates the ionic liquid. This shell provides a barrier that prevents skin penetration while maintaining the flexibility and ionic conductivity needed for electrode function, effectively containing the potentially harmful small molecular weight ionic liquid.
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 bio-electrode composition maintains high conductivity and biocompatibility, preventing skin irritation and peeling, even with exposure to water or drying, and supports stable signal detection over extended periods.
Implementation Method 1
a bio-electrode composition including (A) an ionic resin, wherein the component (A) contains a resin having a structure selected from an ammonium salt, a lithium salt, a sodium salt, and a potassium salt of trissulfonium methide
Implementation Method 2
The water-soluble gel contains sodium, potassium, or calcium as the electrolyte in a water-soluble polymer for retaining water, and converts a change of ion concentration from skin into electricity
Data Source
AI summary
The present invention is a bio-electrode composition includes (A) an ionic resin, wherein the component (A) contains a resin having a structure selected from an ammonium salt, a lithium salt, a sodium salt, and a potassium salt of trissulfonium methide. This provides a bio-electrode composition capable of forming a living body contact layer for a bio-electrode, which is excellent in electric conductivity and biocompatibility and lightweight, can be produced at low cost, causes no significant decrease in the electric conductivity even when gets wet from water or when dried, and is soft with excellent stretchability and adhesiveness; a bio-electrode including a living body contact layer formed from the bio-electrode composition; and a method for producing the bio-electrode.