Dry Bio-Electrode Salt Permeation Layer Conductivity
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Solution Overview
Problem
Current bio-electrodes face challenges in maintaining electric conductivity and biocompatibility over time, particularly when exposed to water or sweat, and often cause skin allergies due to the use of materials like hydrophilic gels, metal nanowires, and conductive polymers, which also suffer from reduced ion conductivity and slow signal detection.
Innovation Solution
A dry-type bio-electrode with a water-free resin layer and a permeation layer containing water-soluble salts and a polymer compound with specific salt structures, enhancing ionic conductivity and biocompatibility, while preventing conductivity loss when wet or dry, and allowing quick signal collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic gel containing water and electrolytes is used as electrode material, then electric conductivity is improved, but water evaporation during drying process causes loss of electric conductivity
Solution Approach 1:
The patent changes the physical state parameter of the electrode material from wet (hydrophilic gel) to dry (water-free resin), eliminating water evaporation issues while maintaining ionic conductivity through alternative mechanisms in the dry state
Solution Approach 2:
The patent uses composite materials combining water-free resin with specific salts (sodium chloride, potassium chloride, calcium chloride, magnesium chloride) to achieve ionic conductivity without water, replacing the traditional hydrophilic gel composition
2Reliability
If higher-ionization-tendency metal such as copper is used to improve electric conductivity, then conductivity is enhanced, but skin allergy occurs
Solution Approach 1:
The patent substitutes metallic conduction with ionic conduction mechanism, using salts embedded in water-free resin to transport ions instead of electron conduction through metals, thereby avoiding metal-induced skin allergies
Solution Approach 2:
The patent changes the conduction mechanism from electronic conduction (metals) to ionic conduction (salts in resin), fundamentally altering how electricity is transmitted while improving biocompatibility
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used to improve conductivity, then electric conductivity is enhanced, but skin allergy occurs due to strong acidity and peeling during washing
Solution Approach 1:
The patent replaces electro-conductive polymer-based electronic conduction with salt-based ionic conduction, eliminating the acidity and peeling problems associated with polymers like PEDOT-PSS
Solution Approach 2:
The patent uses simple, stable salt compounds embedded in durable water-free resin instead of complex, unstable electro-conductive polymers, creating a more reliable and biocompatible electrode material
4Reliability
If metal nanowire is used to improve electric conductivity, then conductivity is enhanced with small quantities, but skin allergy occurs due to pointed thin material
Solution Approach 1:
The patent substitutes metal nanowire electronic conduction with salt crystal ionic conduction, using benign salt particles instead of potentially irritating metal nanowires to achieve conductivity through ion transport
5Reliability
If carbon nanotube is used to improve electric conductivity, then conductivity is enhanced, but skin stimulation occurs
Solution Approach 1:
The patent replaces carbon nanotube electronic conduction with salt-based ionic conduction, using biocompatible salt crystals instead of potentially irritating carbon nanotubes to achieve the desired conductivity
6Reliability
If carbon black is used to improve electric conductivity, then conductivity is enhanced, but skin stimulation occurs to certain degree
Solution Approach 1:
The patent substitutes carbon black electronic conduction with salt-based ionic conduction, using chemically inert salt particles instead of carbon black to achieve conductivity without skin stimulation
7Reliability
If precious metal is used to improve electric conductivity, then conductivity is enhanced, but ion conversion efficiency is poor resulting in high impedance
Solution Approach 1:
The patent replaces precious metal electronic conduction with salt-based ionic conduction, using highly ionizable salt compounds (sodium chloride, potassium chloride, calcium chloride, magnesium chloride) that efficiently convert ion concentration changes into electrical signals, achieving low impedance
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 excellent electric conductivity and biocompatibility, maintaining performance even when wet or dry, with improved ionic conductivity and rapid signal detection, making it suitable for long-term medical wearable devices.
Implementation Method 1
detects changes in ion concentration from the skin to convert the data into electricity
Implementation Method 2
the human skin releases not only extremely weak current, but also a sodium ion, a potassium ion, and a calcium ion
Implementation Method 3
a water-free resin layer... capable of preventing conductivity loss when wet or dry
Data Source
AI summary
A bio-electrode includes an electro-conductive base material and a living body contact layer. The living body contact layer includes a water-free resin layer and a permeation layer on a surface side of the resin layer where a living body comes into contact. The permeation layer is permeated with water and a water-soluble salt selected from the group consisting of sodium salts, potassium salts, calcium salts, magnesium salts, and betaines. This aims to provide: a dry-type bio-electrode that enables quick signal collection after attachment to skin, the bio-electrode being excellent in electric conductivity and biocompatibility, light-weight, and manufacturable at low cost, and capable of preventing significant reduction in the electric conductivity even when wetted with water or dried; a method for manufacturing the bio-electrode; and a method for measuring a biological signal.