Bio-electrode Composition with Ionic Liquid 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, particularly when exposed to water or used for extended periods, as they often suffer from conductivity loss and skin allergies due to materials like silver or PEDOT-PSS.
Innovation Solution
A bio-electrode composition featuring a resin with urethane bonds in the main chain and siloxane bonds in the side chain, combined with electro-conductive materials like fluorosulfonic acid salts, sulfonimide salts, or sulfonamide salts, which form a stable and flexible living body contact layer that maintains conductivity and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble gel containing water and electrolyte is used for bio-electrode, then ionic conductivity is improved, but electric conductivity is lost when water is lost due to drying
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid (water-based gel) to solid (ionic liquid), which eliminates the drying issue while maintaining ionic conductivity. This parameter change resolves the contradiction between maintaining ionic conductivity and preventing conductivity loss upon drying.
Solution Approach 2:
The patent uses a composite structure combining ionic liquid with polymer materials to create a solid-state electrolyte that maintains both ionic conductivity and structural stability. This composite approach allows the bio-electrode to retain electric conductivity without requiring water, thus resolving the contradiction.
2Reliability
If metal with high ionization tendency such as copper is used for bio-electrode, then electron conductivity is improved, but skin allergies are caused
Solution Approach 1:
The patent introduces ionic liquid as an intermediary material between the electrode and skin, which provides the necessary conductivity while eliminating direct contact with allergenic metals. This intermediary layer resolves the contradiction by maintaining electron conductivity without causing skin allergies.
Solution Approach 2:
The patent replaces metal-based electron conduction with ionic conduction through ionic liquid, fundamentally changing the conduction mechanism. This substitution eliminates the harmful effects of metal ionization while maintaining the essential conductivity function.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used for bio-electrode, then electron conductivity is improved, but skin allergies are caused due to strong acidity
Solution Approach 1:
The patent uses ionic liquid as a mediator that provides conductivity without the acidic properties of PEDOT-PSS. This intermediary approach maintains electron conductivity while eliminating the skin allergy issue caused by strong acidity.
Solution Approach 2:
The patent changes the chemical parameter of the electro-conductive material from acidic polymer to neutral ionic liquid, which eliminates the skin irritation caused by acidity while maintaining the necessary conductivity for bio-electrode function.
4Object-affected harmful factors
If urethane is used for bio-electrode, then biocompatibility is improved, but hydrolysis occurs due to higher hydrophilicity
Solution Approach 1:
The patent creates a composite material system where ionic liquid is integrated with urethane or silicone polymer matrices. This composite structure provides the biocompatibility of urethane while the ionic liquid component resists hydrolysis, thus resolving the contradiction between biocompatibility and chemical stability.
Solution Approach 2:
The ionic liquid acts as an intermediary that reduces the direct interaction between water and the urethane polymer chains, thereby preventing hydrolysis while maintaining the biocompatible surface properties of urethane.
5Object-affected harmful factors
If silicone is used for bio-electrode, then biocompatibility and water repellency are improved, but electric conduction is poor due to insulating properties
Solution Approach 1:
The patent creates a composite material where ionic liquid is incorporated into silicone polymer matrices. The ionic liquid provides the necessary electric conduction pathways while the silicone matrix maintains biocompatibility and water repellency, thus resolving the contradiction between these properties.
Solution Approach 2:
The patent applies local quality by concentrating ionic liquid in specific regions or phases within the silicone matrix, creating conductive pathways only where needed while maintaining the overall insulating and biocompatible properties of the silicone material.
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 efficient electric signal conduction from the skin, prevents skin allergies, is lightweight, and remains effective even when wet or dried, making it suitable for long-term medical wearable devices.
Implementation Method 1
The bio-electrode composition ensures efficient electric signal conduction from the skin
Implementation Method 2
it has started to use silicone for use such as medical tubes and so on since silicone is excellent in biocompatibility and repels water such as perspiration
Implementation Method 3
an electro-conductive material, wherein the electro-conductive material is a polymer compound having one or more repeating units selected from the group consisting of fluorosulfonic acid salts, sulfonimide salts, and sulfonamide salts
Implementation Method 4
a resin containing a urethane bond in a main chain and a siloxane bond in a side chain
Data Source
AI summary
The present invention provides a bio-electrode composition including: a resin containing a urethane bond in a main chain and a siloxane bond in a side chain; and an electro-conductive material, wherein the electro-conductive material is a polymer compound having one or more repeating units selected from fluorosulfonic acid salts shown by the following formulae (1)-1 and (1)-2, sulfonimide salts shown by the following formula (1)-3, and sulfonamide salts shown by the following formula (1)-4. This can form a living body contact layer for a bio-electrode that is excellent in electric conductivity and biocompatibility, light in weight, manufacturable at low cost, and free from large lowering of the electric conductivity even when it is wetted with water or dried. The present invention also provides a bio-electrode in which the living body contact layer is formed from the bio-electrode composition, and a method for manufacturing the bio-electrode.