Bio-electrode Composition with Ionic and Acrylate Units for Stable Conductivity
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Solution Overview
Problem
Current bio-electrodes face challenges in maintaining electric conductivity and biocompatibility while being lightweight and cost-effective, especially when exposed to water or used for extended periods, due to issues with ionization, skin allergies, and fluctuations in contact area with the skin.
Innovation Solution
A bio-electrode composition comprising a polymer compound with both ionic and (meth)acrylate repeating units, along with additional components like carbon materials or metal-coated particles, which forms a living body contact layer that maintains conductivity and biocompatibility, is developed. This composition includes specific ionic repeating units and copolymerization with units providing tackiness and repellency, ensuring stable signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water soluble gel containing water and electrolyte is used for bio-electrode, then electric conductivity is achieved, but electric conductivity is lost as water is lost due to drying
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid (water-based) to solid (polymer matrix), eliminating the drying problem while maintaining ion conduction pathways. The gel structure is reformulated to retain electrolyte ions without free water, achieving both stability and conductivity.
Solution Approach 2:
The patent creates a composite material system combining polymer matrix with electrolyte ions and conductive additives. This composite structure provides both mechanical stability and electrical conductivity, resolving the contradiction between water loss and conductivity maintenance.
2Reliability
If metal with high ionization tendency such as copper is used for bio-electrode, then electric conductivity is improved, but skin allergies are caused
Solution Approach 1:
The patent replaces reactive metal electrodes with stable polymer-based electrodes that do not ionize. The conductive polymer serves as a non-reactive alternative that maintains conductivity without the harmful ionization that causes skin allergies, effectively substituting a harmful material with a safe one.
Solution Approach 2:
The patent introduces a conductive polymer as an intermediary layer between the metal electrode and skin contact. This polymer mediates the interaction by providing conductivity while preventing direct metal-skin contact that would cause allergic reactions from metal ionization.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used for bio-electrode, then electric conductivity is achieved, but skin allergies are caused due to strong acidity
Solution Approach 1:
The patent modifies the chemical parameters of the electro-conductive polymer by adjusting pH and composition to reduce acidity. The polymer is reformulated to maintain conductivity while eliminating the strong acidic properties that cause skin allergies, achieving a balance between electrical performance and biocompatibility.
4Reliability
If metal nanowire is used for bio-electrode, then electric conductivity is improved with small loading amount, but skin allergies are caused due to sharp tips
Solution Approach 1:
The patent replaces metal nanowires with polymer-based conductive materials that lack sharp edges. The conductive polymer provides sufficient conductivity without the mechanical sharpness that penetrates skin and causes allergies, offering a safer alternative with comparable electrical performance.
5Reliability
If noble metal is used for bio-electrode, then electric conductivity is achieved, but ion conversion from skin to current is inefficient
Solution Approach 1:
The patent changes the surface properties and chemical composition of the electrode to enhance ion interaction. The conductive polymer is designed with functional groups that facilitate ion adsorption and conversion, improving the efficiency of transforming ionic signals from skin into electrical currents while maintaining high 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 achieves efficient electric signal conduction, avoids skin allergies, maintains conductivity in wet or dry conditions, and is lightweight, making it suitable for long-term medical wearable devices with improved adhesion and elasticity.
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
the (meth)acrylate repeating unit B is a repeating unit shown by general formula (2)... having tackiness
Implementation Method 3
the copolymerization with units having fluorine atoms... providing repellency
Data Source
AI summary
The present invention provides a bio-electrode composition including a polymer compound having both an ionic repeating unit A and a (meth)acrylate repeating unit B, wherein the ionic repeating unit A is a repeating unit selected from the group consisting of sodium salt, potassium salt, and ammonium salt having either or both partial structures shown by the following general formulae (1-1) and (1-2), and the (meth)acrylate repeating unit B is a repeating unit shown by the following general formula (2).This can form a living body contact layer for a bio-electrode with excellent electric conductivity, biocompatibility, and light weight, which can be manufactured at low cost and does not cause large lowering of the electric conductivity even when it is wetted with water or dried.