Silver-Salt Bio-Electrode Composition for Wet-Dry Skin Contact
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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 or skin allergies due to materials like metal nanowires, carbon nanotubes, and ionic liquids.
Innovation Solution
A bio-electrode composition incorporating a polymer compound with silver salts of fluorosulfonic acid, fluorosulfonimide, or fluorosulfonamide, combined with carbon materials and metal particles, which forms a durable and conductive living body contact layer that retains conductivity and biocompatibility even when wet or dry.
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 achieved, but electric conductivity is lost when water is lost due to drying
Solution Approach 1:
The patent changes the physical state of the electrolyte from aqueous (water-based) to anhydrous (water-free) form. Specifically, it uses ionic liquids or solid electrolytes instead of water soluble gels, fundamentally altering the composition parameter to eliminate water while maintaining ionic conductivity. This resolves the contradiction by making the electrolyte stable without water.
Solution Approach 2:
The patent employs composite material structures combining multiple components: electro-conductive polymer base materials (like PEDOT-PSS), ionic liquids, or solid electrolytes with specific polymers (polyacrylic acid, polyvinyl alcohol). These composites achieve both high electric conductivity and stability without water, resolving the contradiction between conductivity and compositional stability.
2Reliability
If metal nanowire is used as electrode material, then electric conductivity is improved, but skin allergies are caused due to sharp tips
Solution Approach 1:
The patent uses composite materials combining electro-conductive polymers (PEDOT-PSS) with ionic liquids or solid electrolytes, replacing metal nanowires entirely. This composite approach maintains high electric conductivity through ionic conduction while eliminating the sharp tips and skin irritation associated with metal nanowires.
Solution Approach 2:
The patent introduces ionic liquids or solid electrolytes as intermediary substances that enable ionic conduction between the electro-conductive polymer and the skin. This intermediary mechanism replaces direct electron conduction through metal nanowires, eliminating skin contact with sharp metal tips while maintaining conductivity function.
3Reliability
If carbon nanotube is used as electrode material, then electric conductivity is improved, but skin irritation is caused due to sharp tips
Solution Approach 1:
The patent replaces carbon nanotubes with composite materials consisting of electro-conductive polymers (PEDOT-PSS) combined with ionic liquids or solid electrolytes. This substitution maintains ionic conductivity while eliminating the sharp tips and skin irritation caused by carbon nanotube structures.
4Reliability
If ionic liquid with smaller molecular weight is used in bio-electrode, then electric conductivity is improved, but skin permeation occurs causing rough dry skin
Solution Approach 1:
The patent changes the molecular weight parameter of the ionic liquid to larger values, or alternatively uses solid electrolytes instead. This parameter change reduces skin permeation while maintaining ionic conductivity, resolving the contradiction between conductivity improvement and skin safety.
Solution Approach 2:
The patent uses solid electrolytes or larger molecular weight ionic liquids that remain on the skin surface without permeating, effectively creating a non-permeable barrier layer that maintains conductivity without causing skin damage over extended wear periods.
5Reliability
If noble metal is used as bio-electrode material, then electric conductivity is improved, but ionization efficiency is low causing high impedance
Solution Approach 1:
The patent replaces electron conduction mechanisms (metallic conduction in noble metals) with ionic conduction mechanisms. By using ionic liquids or solid electrolytes combined with electro-conductive polymers, the system substitutes the conduction mechanism to achieve both high conductivity and efficient ion-to-current conversion at the skin interface.
Solution Approach 2:
The patent uses composite materials combining electro-conductive polymers with ionic liquids or solid electrolytes, creating a material that facilitates efficient ion conduction and conversion to electrical current, overcoming the ionization inefficiency of noble metals 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 composition ensures stable electric signal transmission with excellent biocompatibility and lightweight design, preventing conductivity loss and skin allergies, and can be manufactured at low cost with enhanced tackiness and elasticity for long-term wearability.
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
it is a sodium, potassium, or calcium ion that is emitted from skin caused by heartbeat, not a weak current signal. This makes it necessary to convert the change of ion concentration to current
Implementation Method 3
As the electrode material, it has been investigated to use metal nanowire, carbon black, carbon nanotube and so on since they have excellent electric conductivity
Implementation Method 4
the bio-electrode preferably has tackiness. It also needs elasticity and flexibility to cope with expansion and contraction as well as change of bending of skin
Data Source
AI summary
The present invention provides a bio-electrode composition comprising a polymer compound having a repeating unit A that contains silver salt of fluorosulfonic acid, silver salt of fluorosulfonimide, or silver salt of fluorosulfonamide. 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. 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.