Ionic Polymer Bio-electrode Composition for Skin Contact
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Solution Overview
Problem
Current bio-electrodes face challenges in maintaining long-term electric conductivity and biocompatibility, often causing skin allergies and residue issues due to water evaporation, acidity of materials, and high impedance, while also requiring immediate signal detection and stable adhesion.
Innovation Solution
A bio-electrode composition incorporating an ionic polymer material with specific salt structures and radical-polymerizable double bonds, combined with a resin and optional additives like carbon or lithium titanate, to form a living body contact layer that enhances ionic conductivity, prevents residue, and ensures biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water soluble gel containing water and electrolyte is used as bio-electrode, then electric conductivity is improved, but water evaporation during drying process causes loss of electric conductivity
Solution Approach 1:
The invention changes the physical state parameter of the gel from wet to dry by controlling the drying process. The gel is designed to maintain its ion-conductive properties even in the dry state through specific polymer and electrolyte selection, allowing water removal without losing electric conductivity.
Solution Approach 2:
The invention uses a composite material system consisting of ion-conductive polymer, inorganic electrolyte, and optional organic electrolyte. This composite structure maintains ion conductivity without relying on water, solving the evaporation problem while preserving electric conductivity.
2Reliability
If higher-ionization-tendency metal such as copper is used, then electric conductivity is improved, but skin allergy occurs
Solution Approach 1:
The invention introduces an ion-conductive polymer as an intermediary layer between the metal electrode and the skin. This polymer layer provides ion conduction functionality while physically separating the potentially allergenic metal from direct skin contact, thus maintaining conductivity without causing skin allergy.
Solution Approach 2:
The invention changes the conduction mechanism from direct metal-to-skin electron conduction to polymer-mediated ion conduction. This parameter change in the conduction pathway eliminates the harmful effect of metal skin contact while preserving the electric conductivity function.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used, then electric conductivity is improved, but skin allergy occurs due to strong acidity and peeling during washing
Solution Approach 1:
The invention changes the pH parameter of the electro-conductive material by selecting polymers with appropriate acid-base properties. The selected ion-conductive polymers have neutral or mild pH characteristics, eliminating the strong acidity that causes skin allergy while maintaining electric conductivity through ion transport.
Solution Approach 2:
The invention uses a composite of ion-conductive polymer and inorganic electrolyte that provides stable adhesion and conductivity. This composite structure prevents peeling during washing while maintaining the electro-conductive properties needed for signal detection.
4Reliability
If metal nanowire, carbon black, or carbon nanotube is used, then electric conductivity is improved, but biocompatibility is degraded due to sharp tips causing skin stimulation
Solution Approach 1:
The invention changes the physical form parameter from discrete particles with sharp tips to a continuous gel matrix. This eliminates the sharp tip effect that causes skin stimulation while maintaining high electric conductivity through the interconnected polymer-electrolyte network.
Solution Approach 2:
The invention uses a composite gel system where the polymer matrix and electrolyte work together to provide both mechanical compliance (reducing skin irritation) and high ion conductivity, replacing the problematic particulate materials.
5Reliability
If noble metal is used, then electric conductivity is improved, but impedance and resistance to skin during electrical conduction increase due to difficulty in ionization
Solution Approach 1:
The invention replaces the electron conduction mechanism of metals with ion conduction mechanism in the polymer-electrolyte gel. This substitution allows for direct ion-to-electron conversion at the skin interface, reducing impedance and resistance while maintaining conductivity.
Solution Approach 2:
The ion-conductive polymer gel acts as an intermediary that facilitates efficient ion-to-electron conversion. This mediator layer enables direct transduction of ionic signals from skin to electronic signals in the electrode, reducing impedance without requiring noble metals.
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 enables immediate signal collection, prevents skin residue, maintains conductivity even when wet or dry, and ensures biocompatibility, making it suitable for long-term use without causing skin irritation.
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
a repeating unit-b having a side chain with a radical-polymerizable double bond in a structure selected from the group consisting of (meth)acrylate, vinyl ether, and styrene
Data Source
AI summary
A bio-electrode composition contains (A) an ionic polymer material. The component (A) is a polymer compound containing: a repeating unit-a having a structure selected from the group consisting of salts of ammonium, sodium, potassium, and silver formed with any of fluorosulfonic acid, fluorosulfonimide, and N-carbonyl-fluorosulfonamide; and a repeating unit-b having a side chain with a radical-polymerizable double bond in a structure selected from the group consisting of (meth)acrylate, vinyl ether, and styrene. Thus, the present invention provides: a bio-electrode composition capable of forming a living body contact layer for a bio-electrode to enable signal collection immediately after attachment to skin and prevention of residue on the skin after peeling from the skin; a bio-electrode including a living body contact layer formed of the bio-electrode composition; and a method for manufacturing the bio-electrode.