Ionic Polymer Bio-electrode Composition for Stable Conductivity
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Solution Overview
Problem
Current bio-electrodes face challenges in maintaining electric conductivity and biocompatibility, particularly when exposed to water or used for extended periods, due to issues with water evaporation, skin allergies, and reduced adhesion and stretchability, which affect the reliability of long-term biological signal detection.
Innovation Solution
A bio-electrode composition comprising an ionic polymer material bonded to carbon particles, specifically using salts of ammonium, lithium, sodium, and silver with fluorosulfonic acid, fluorosulfonimide, or N-carbonyl-fluorosulfonamide, combined with an adhesive resin and electro-conductive powders, to enhance both ionic and electron conductivity while preventing permeation and irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble gel containing water and electrolyte is used as bio-electrode material, then electric conductivity is improved, but water evaporation during drying process causes loss of electric conductivity
Solution Approach 1:
The patent uses an adhesive resin as an intermediary substance that binds the ionic polymer material to the carbon particles. This composite structure allows the ionic polymer to maintain its ion-conducting properties while the carbon particles provide structural stability and prevent water loss, resolving the contradiction between maintaining electric conductivity and preventing water evaporation.
Solution Approach 2:
The patent creates a composite material consisting of ionic polymer material bonded to carbon particles. This composite combines the ion-conducting properties of the polymer with the structural stability and water-retention capabilities of carbon particles, enabling the bio-electrode to maintain electric conductivity even when dried.
2Reliability
If higher-ionization-tendency metal such as copper is used to improve electric conductivity, then conductivity is enhanced, but skin allergy occurs
Solution Approach 1:
The patent changes the material parameter from reactive metals (copper) to ionic polymer materials that provide ionization without causing skin allergies. The ionic polymer material achieves the necessary ionization for conductivity while being biocompatible, thus resolving the contradiction between electric conductivity and skin allergy prevention.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used to improve conductivity, then electric conductivity is enhanced, but skin allergy occurs due to strong acidity and peeling during washing
Solution Approach 1:
The patent changes the chemical properties of the electro-conductive material by using ionic polymer materials with appropriate ionization tendencies that do not exhibit strong acidity. This eliminates skin allergy while maintaining conductivity. Additionally, the bonding to carbon particles prevents peeling during washing by providing mechanical stability.
4Reliability
If metal nanowire is used to improve electric conductivity with small quantities, then conductivity is enhanced, but skin allergies occur due to sharp tips and thin structure
Solution Approach 1:
The patent changes the physical form from thin metal nanowires with sharp tips to ionic polymer materials that can be applied as coatings. This eliminates the mechanical irritation caused by sharp tips while maintaining ionization capability for conductivity, thus preventing skin allergies.
5Reliability
If noble metal film is used to improve electric conductivity, then conductivity is enhanced, but high impedance and high resistance to skin occur during electrical conduction
Solution Approach 1:
The patent changes the material from noble metals with low ionization tendency to ionic polymer materials that readily ionize. This enables efficient conversion of ions from skin to current, reducing impedance and resistance during electrical conduction while maintaining good electric conductivity.
6Reliability
If ionic liquid with smaller molecular weight is used to improve electric conductivity, then conductivity is enhanced, but ionic liquid dissolves into water and is extracted by sweating, lowering conductivity and causing rough dry skin
Solution Approach 1:
The patent creates a composite where the ionic polymer material is bonded to carbon particles. This structure prevents the ionic material from dissolving into water or being extracted by sweating, as the carbon particle framework provides structural stability and anchors the ionic polymer in place, maintaining conductivity during perspiration.
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 and sensitive detection of biological signals over time, maintaining conductivity and biocompatibility, even when wet or dried, with improved adhesion and stretchability, thus addressing the limitations of existing technologies.
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 changes of ion concentration from skin into electricity.
Implementation Method 2
By taking advantage of excellent electric conductivity, the use of metal nanowire, carbon black, carbon nanotube, and the like as electrode materials has been examined
Data Source
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AI summary
A bio-electrode composition contains (A) a reaction composite of an ionic polymer material and a carbon particle. The component (A) contains the carbon particle bonding to the polymer containing a repeating unit having a structure selected from the group consisting of salts of ammonium, lithium, sodium, potassium, and silver formed with any of fluorosulfonic acid, fluorosulfonimide, and N-carbonyl-fluorosulfonamide. Thus, the present invention 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, light-weight, and manufacturable at low cost, and which prevents significant reduction in the electric conductivity even when wetted with water or dried; a bio-electrode including a living body contact layer formed of the bio-electrode composition; and a method for manufacturing the bio-electrode.