Bio-electrode Composition with Sulfonimide Polymer for Stable Conductivity
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Solution Overview
Problem
Current bio-electrodes for wearable devices face challenges in maintaining conductivity and biocompatibility over long-term use, often experiencing conductivity loss due to water evaporation or causing skin allergies, and fail to efficiently convert ion concentration changes into electrical signals.
Innovation Solution
A bio-electrode composition incorporating a polymer compound with sodium, potassium, or ammonium sulfonimide salts and silicon atoms, combined with a resin and carbon materials, which forms a conductive and biocompatible living body contact layer that remains effective when soaked in water or dried, and is lightweight and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic gel containing water and electrolytes is used as electrode, then conductivity is improved, but water evaporation during drying process causes loss of conductivity
Solution Approach 1:
The patent changes the physical state parameter from liquid water-based gel to solid polymer electrolyte, eliminating evaporation while maintaining ionic conductivity through the polymer matrix structure
Solution Approach 2:
The patent creates a composite material combining hydrophilic polymer chains with ionic liquid or electrolyte salts, forming a solid polymer electrolyte that provides both structural integrity and ionic conduction pathways
2Reliability
If higher ionization tendency metal such as copper is used, then conductivity is improved, but skin allergy is caused
Solution Approach 1:
The patent uses biocompatible polymer electrolyte materials that can be safely disposed of after use, eliminating the need for expensive precious metals while ensuring skin safety through inherent biocompatibility of the polymer material
Solution Approach 2:
The patent changes the material composition from reactive metals to inert polymer electrolytes, maintaining ionic conductivity through ion transport mechanisms while eliminating metal-induced allergic reactions
3Reliability
If conductive polymer such as PEDOT-PSS is used, then conductivity is improved, but strong acidity causes skin allergy
Solution Approach 1:
The patent changes the pH parameter from strongly acidic to neutral or slightly basic by using polymer electrolytes with pH values between 6-8, eliminating skin irritation while maintaining ionic conductivity through the polymer structure
Solution Approach 2:
The patent creates a composite polymer electrolyte system that combines conductive polymer chains with ionic liquid or electrolyte salts, achieving conductivity through ion transport rather than acidic proton conduction
4Reliability
If metal nanowire is used, then conductivity is improved with small quantity addition, but pointed thin material causes skin allergy
Solution Approach 1:
The patent uses biocompatible polymer electrolyte materials that are inherently safe for skin contact, eliminating the need for metal nanowires while providing sufficient conductivity through the polymer matrix and ionic liquid combination
5Reliability
If carbon nanotube is used, then conductivity is improved, but material stimulates living body
Solution Approach 1:
The patent uses biocompatible polymer electrolyte materials that are inherently safe for prolonged skin contact, providing conductivity through ionic transport mechanisms rather than carbon nanotube electron conduction
6Reliability
If carbon black is used, then conductivity is improved, but material stimulates skin
Solution Approach 1:
The patent creates a composite polymer electrolyte system where hydrophilic polymer chains provide a flexible matrix and ionic liquid or electrolyte salts provide ionic conduction pathways, achieving conductivity without skin irritation
7Reliability
If ionic liquid with smaller molecular weight is used, then conductivity is improved, but ionic liquid dissolves into water and causes skin roughness
Solution Approach 1:
The patent creates a composite system where ionic liquid is embedded within a hydrophilic polymer matrix, providing high ionic conductivity through the liquid phase while the polymer network prevents excessive water solubility and skin penetration
Solution Approach 2:
The patent uses the hydrophilic polymer as a flexible matrix that contains the ionic liquid, creating a gel-like structure that maintains ionic mobility while providing a protective barrier against skin irritation
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 conductivity and biocompatibility, maintaining signal transmission efficiency even with long-term skin contact, and can be manufactured at a lower cost, with the addition of carbon materials enhancing conductivity and the use of polymers improving adhesion and elasticity.
Implementation Method 1
the above conductive paste (International Patent Laid-Open Publication No. WO 2013/039151). The hydrophilic gel, containing sodium, potassium, and calcium electrolytes in a hydrophilic polymer containing water, detects changes in ion concentration from the skin to convert the data into electricity
Implementation Method 2
By taking advantage of excellent conductivity, the use of electrode materials formed of metal nanowire, carbon black, or carbon nanotube has been examined
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The present invention provides a bio-electrode composition capable of forming a living body contact layer for a bio-electrode that is excellent in conductivity and biocompatibility, is light-weight, can be manufactured at low cost, and can control significant reduction in conductivity even though the bio-electrode is soaked in water or dried. The present invention is accomplished by a bio-electrode composition including an (A) ionic material and a (B) resin other than the component (A), in which the component (A) has both a repeating unit "a" of a sodium salt, a potassium salt, or an ammonium salt including a partial structure represented by the following general formula (1) and a repeating unit "b" having a silicon atom. -R1-SO2-N--SO2-Rf1 M+ (1)