Ionic Resin Bio-Electrode Composition for Stable Skin Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bio-electrodes for wearable devices face challenges in maintaining electric conductivity and biocompatibility over long-term use, often causing skin allergies and peeling issues due to materials like water-soluble gels, metal nanowires, and conductive polymers, while noble metals and ionic liquids lead to high impedance and skin penetration.
Innovation Solution
A bio-electrode composition using an ionic resin with ammonium, lithium, or potassium salts of trissulfonium methide, combined with silicone resin and carbon or metal powders, to create a soft, adhesive, and stretchable layer that maintains conductivity and biocompatibility, even when wet or dry.
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 achieved, but electric conductivity is lost when water dries out
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid (water-based gel) to solid (ionic resin), enabling the material to maintain its electro-conductive function without requiring water content. This parameter change resolves the contradiction by eliminating the drying issue while preserving electric conductivity for long-term wearable use.
Solution Approach 2:
The patent creates a composite material system combining ionic resin with polymer adhesive and conductive fillers (metal nanowires, carbon black, or graphene). This composite structure integrates the electro-conductive function of ionic resin with the adhesive properties of polymer and the conductivity enhancement of fillers, achieving both reliable electric conductivity and long-term durability.
2Reliability
If metal nanowire is used as electrode material, then electric conductivity is improved, but skin allergies occur due to sharp tips
Solution Approach 1:
The patent uses ionic resin as an intermediary material that surrounds and encapsulates metal nanowires or carbon black particles. This intermediary layer softens the sharp edges of conductive fillers, reducing their stimulativeness to skin while maintaining the overall electric conductivity of the composite electrode material.
Solution Approach 2:
The patent creates a composite structure where metal nanowires or carbon black are dispersed within a matrix of ionic resin and polymer adhesive. This composite approach allows the use of highly conductive fillers while the resin matrix provides a biocompatible interface with skin, resolving the contradiction between conductivity and skin safety.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used, then electric conductivity is achieved, but skin allergies occur due to strong acidity and peeling off during washing
Solution Approach 1:
The patent replaces the acidic electro-conductive polymer (PEDOT-PSS) with ionic resin, fundamentally changing the chemical composition and eliminating the strong acidity parameter. This substitution removes the source of skin irritation while maintaining electro-conductive functionality through the ionic conduction mechanism of the resin.
Solution Approach 2:
The patent employs a polymer adhesive system that provides flexible, washable, and removable attachment without the peeling issues of electro-conductive polymers. This adhesive system allows the electrode to withstand washing and repeated use without degrading or causing skin damage, effectively replacing the problematic electro-conductive polymer function.
4Reliability
If noble metal is used as bio-electrode, then electric conductivity is improved, but impedance and resistance to skin increase due to difficulty of ionization
Solution Approach 1:
The patent substitutes electronic conduction (electron flow in noble metals) with ionic conduction (ion flow in ionic resin). This substitution replaces the electronic conduction mechanism with an ionic conduction mechanism that is more compatible with skin physiology, enabling efficient conversion of skin ions to electrical signals while reducing impedance and resistance.
Solution Approach 2:
The patent changes the conduction mechanism parameter from electronic conduction to ionic conduction. This parameter change allows the electrode to efficiently interact with skin ions (sodium, potassium, calcium) and convert them to electrical signals, reducing the impedance and resistance problems associated with noble metals that have difficulty ionizing.
5Reliability
If ionic liquid with small molecular weight is added to battery, then electric conductivity is improved, but skin penetration occurs causing skin problems
Solution Approach 1:
The patent changes the molecular weight parameter of the ionic compound from small (ionic liquid) to large (ionic resin). This parameter change increases the molecular size beyond the skin penetration threshold while maintaining the ionic conduction capability, thereby eliminating skin penetration issues while preserving electric conductivity.
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 ensures stable electric signal transmission, low skin irritation, and cost-effective production, with enhanced adhesiveness and stretchability, suitable for long-term wear without residue or peeling.
Implementation Method 1
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
Implementation Method 2
Noble metal, however, is difficult to ionize and thus inefficient in converting ions from skin to a current
Data Source
Figure 1~3
Figure 4~6
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.