Bio-electrode Composition Using Ionic Liquid for Stable Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bio-electrodes for wearable devices face challenges in maintaining electric conductivity and biocompatibility over long periods, often experiencing conductivity loss due to water evaporation or causing skin allergies, while also requiring constant contact with the skin to accurately detect physiological signals.
Innovation Solution
A bio-electrode composition comprising silsesquioxane bonded to an N-carbonyl sulfonamide salt, combined with an adhesive resin and electro-conductive powders, which forms a stable living body contact layer that maintains conductivity and biocompatibility, even when wet or dried, and ensures consistent skin contact for accurate signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic gel containing water and electrolytes is used as electrode, 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 electrolyte from liquid (water-based hydrophilic gel) to solid (ionic liquid), eliminating evaporation while maintaining ionic conductivity. The ionic liquid is incorporated into a porous polymer matrix that retains it in a gel-like state, providing stable conductivity without water loss.
Solution Approach 2:
The patent creates a composite structure combining porous polymer material with ionic liquid. The porous polymer provides structural framework and retention, while the ionic liquid fills the pores to provide ionic conductivity, achieving both stability and conductivity without water evaporation issues.
2Reliability
If higher ionization tendency metal such as copper is used to improve electric conductivity, then electric conductivity is improved, but skin allergy occurs
Solution Approach 1:
The patent introduces an intermediary layer consisting of porous polymer and ionic liquid between the metal electrode and the skin. This intermediary layer provides the necessary ionic conductivity for signal detection while physically isolating the skin from direct contact with allergenic metals like copper, eliminating allergic reactions.
Solution Approach 2:
The patent changes the conduction mechanism from direct metal-to-skin electronic conduction to ionic conduction through the ionic liquid medium. This parameter change in conduction pathway allows use of high-conductivity metals without direct skin contact, preventing allergies while maintaining signal quality.
3Reliability
If electro-conductive polymer such as PEDOT-PSS is used to improve electric conductivity, then electric conductivity is improved, but skin allergy and peeling occur due to strong acidity
Solution Approach 1:
The patent replaces problematic electro-conductive polymers with an ionic liquid-based composite that offers superior stability, biocompatibility, and durability. The ionic liquid-porous polymer system provides sustained conductivity without the degradation, peeling, or allergic reactions associated with acidic polymers like PEDOT-PSS.
Solution Approach 2:
The patent changes the chemical composition parameter from acidic polymer to neutral ionic liquid, eliminating the acidity-related harmful effects while maintaining ionic conductivity. The ionic liquid provides a neutral, biocompatible environment that prevents skin irritation and material peeling.
4Reliability
If metal nanowire is used to improve electric conductivity with higher contact probability, then electric conductivity is improved, but skin allergy may occur due to pointed thin material shape
Solution Approach 1:
The patent changes the morphology parameter from needle-like metal nanowires to spherical or irregular ionic liquid droplets embedded in porous polymer. This shape change eliminates the pointed structures that cause skin irritation while maintaining high contact probability and ionic conductivity through the liquid-filled pores.
Solution Approach 2:
The patent introduces porous polymer as an intermediary matrix that holds ionic liquid, replacing direct metal nanowire-to-skin contact. This intermediary structure provides conductivity pathways through the ionic liquid while the porous polymer cushioning eliminates mechanical irritation from sharp structures.
5Reliability
If precious metal is used to improve electric conductivity, then electric conductivity is improved, but high impedance and high resistance to skin occur during electrical conduction
Solution Approach 1:
The patent applies hydraulic principles by using ionic liquid (a liquid electrolyte) as the conduction medium instead of solid metal contact. The liquid ionic liquid can dynamically adapt to skin surface contours, ensuring continuous contact and low impedance, while the ionic conduction mechanism provides low resistance comparable to or better than precious metals.
Solution Approach 2:
The patent changes the conduction mechanism from electronic conduction through solid metal to ionic conduction through liquid electrolyte. This parameter change in conduction type provides both low impedance due to liquid adaptability and low resistance due to high ionic mobility, outperforming solid precious metals in skin contact applications.
6Reliability
If ionic liquid with smaller molecular weight is used to improve electric conductivity, then electric conductivity is improved, but ionic liquid dissolves into water and extracts from electrode by sweating
Solution Approach 1:
The patent uses a nested structure where ionic liquid molecules are confined within the porous network of the polymer matrix. The porous polymer acts as a molecular cage that retains the ionic liquid through capillary forces and physical confinement, preventing extraction by sweat while allowing ionic conductivity through the confined liquid phase.
Solution Approach 2:
The patent uses porous polymer material with controlled pore size and distribution to retain ionic liquid. The porous structure provides capillary retention forces that prevent ionic liquid extraction by sweat, while the interconnected pores allow sufficient ionic mobility for high conductivity. The porous matrix effectively traps the ionic liquid in place during perspiration.
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 achieves high electric conductivity and biocompatibility, preventing significant conductivity loss and skin irritation, while ensuring stable and sensitive signal detection with improved adhesion and stretchability, suitable for long-term medical wearable applications.
Implementation Method 1
the N-carbonyl sulfonamide salt is shown by the following general formula (1): wherein M+ is an ion selected from a lithium ion, a sodium ion, a potassium ion, and a silver ion
Implementation Method 2
combined with an adhesive resin and electro-conductive powders, which forms a stable living body contact layer
Data Source
AI summary
The present invention provides a bio-electrode composition including a silsesquioxane bonded to an N-carbonyl sulfonamide salt, wherein the N-carbonyl sulfonamide salt is shown by the following general formula (1):wherein R1 represents a linear, branched, or cyclic alkylene group having 1 to 20 carbon atoms that may have an aromatic group, an ether group, or an ester group, or an arylene group having 6 to 10 carbon atoms; Rf represents a linear, branched, or cyclic alkyl group having 1 to 4 carbon atoms containing at least one fluorine atom; M+ is an ion selected from a lithium ion, a sodium ion, a potassium ion, and a silver ion. This can form a living body contact layer for a bio-electrode that is excellent in electric conductivity and biocompatibility, light-weight, manufacturable at low cost, and free from large lowering of the electric conductivity even though it is wetted with water or dried.