Printable Adhesive Electrode for Skin Signal Measurement
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Solution Overview
Problem
Current electrodes for bio-signal measurement and electrical stimulation face issues such as short usage times due to drying out, skin irritation, and poor signal quality, along with complex and costly production processes, especially when using gel-based electrodes.
Innovation Solution
A dry stimulation or sensing electrode utilizing an ionically and/or electrically conductive pressure-sensitive adhesive composition comprising an ionic liquid and/or carbon black, combined with a resin like (meth)acrylate, polyurethane, or silicone, which is screen printable and has low solvent content, allowing for long-term use without skin irritation and improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gel-based electrodes are used to ensure good signal quality and low impedance, then skin irritation and short usage time occur due to high salt concentration and water content causing drying out
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by using ionic liquids with specific viscosity ranges (10-1000 cP) and conductivity ranges (0.1-10 mS/cm), replacing traditional gel formulations with high salt concentration. This parameter change maintains electrical conductivity while eliminating the high salt concentration that causes skin irritation, thus resolving the contradiction between signal quality and skin comfort
Solution Approach 2:
The patent creates a composite adhesive material combining ionic liquid conductive fillers with polymer matrices (acrylate, polyurethane, or silicone resins). This composite structure provides both the electrical conductivity needed for signal quality and the mechanical properties for skin-friendly adhesion, eliminating the need for high salt concentration gels that irritate skin
2Measurement precision
If gel-based electrodes are used to ensure good signal quality, then usage time is limited to maximum 24-48 hours due to drying out from high water content
Solution Approach 1:
The patent changes the physical state parameter of the conductive medium from water-based gel to ionic liquid-based adhesive. Ionic liquids have negligible vapor pressure and do not evaporate or dry out like water-based gels, enabling continuous use for several days or weeks while maintaining stable electrical conductivity and signal quality
Solution Approach 2:
The patent transitions from disposable short-lived gel electrodes to long-lasting reusable adhesive electrodes. The ionic liquid-infused pressure-sensitive adhesive maintains its conductive properties over extended periods without drying out, eliminating the need for frequent replacement and reducing waste
3Ease of manufacture
If tab electrodes with gel-type adhesive are used to eliminate additional skin adhesive, then cohesive failure occurs upon removal due to poor cohesion
Solution Approach 1:
The patent develops a composite pressure-sensitive adhesive material where ionic liquid conductive fillers are integrated within a polymer matrix (acrylate, polyurethane, or silicone). This composite structure provides both the electrical conductivity of gel and the mechanical cohesion of pressure-sensitive adhesives, enabling strong bonding to skin and substrate without cohesive failure upon removal
Solution Approach 2:
The patent creates a multi-functional adhesive that simultaneously provides electrical conductivity, skin adhesion, and substrate bonding in a single layer. The ionic liquid-infused pressure-sensitive adhesive serves both as the conductive medium for signal transmission and as the bonding agent between electrode and skin, eliminating the need for separate gel and adhesive layers while maintaining strong cohesion
4Measurement precision
If electrophoretic alignment of conductive fillers is used to obtain sufficient impedance, then production becomes expensive and complicated
Solution Approach 1:
The patent replaces the complex electrophoretic process (electrical field-based alignment) with a simpler mechanical mixing and coating process. The ionic liquid-infused adhesive is applied directly to the conductive layer using conventional coating techniques, and the conductive fillers achieve adequate distribution and impedance control without requiring electrophoretic activation, significantly simplifying production
Solution Approach 2:
The patent adopts a simpler, more cost-effective adhesive application process that eliminates expensive electrophoretic equipment and complex production steps. The ionic liquid-based adhesive can be applied using standard coating or lamination processes, reducing manufacturing costs and complexity while achieving sufficient impedance control for electrode operation
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 solution enables prolonged use of electrodes with stable impedance and adhesion, reduced skin irritation, and simplified production processes, while maintaining good current distribution and breathability, thus addressing the limitations of existing gel-based electrodes.
Implementation Method 1
an ionic liquid selected from the group consisting of imidazolium acetates, imidazolium sulfonates, imidazolium chlorides, imidazolium sulphates, imidazolium phosphates, imidazolium thiocyanates, imidazolium dicyanamides, imidazolium benzoates, choline triflates, choline saccharinate, choline sulfamates, pyridinium acetates, pyridinium sulfonates, pyridinium chlorides, pyridinium sulphates, pyridinium phosphates, pyridinium thiocyanates, pyridinium dicyanamides, pyridinium benzoates, pyrrolidinium acetates, pyrrolidinium sulfonates, pyrrolidinium chlorides, pyrrolidinium sulphates, pyrrolidinium phosphates, pyrrolidinium thiocyanates, pyrrolidinium dicyanamides, phosphonium acetates, phosphonium sulfonates, phosphonium chlorides, phosphonium sulphates, phosphonium phosphates, phosphonium thiocyanates, sulfonium acetates, sulfonium sulfonates, sulfonium chlorides, sulfonium sulphates, sulfonium phosphates, sulfonium thiocyanates, ammonium acetates, ammonium sulfonates, ammonium chlorides, ammonium sulphates, ammonium phosphates, ammonium thiocyanates, ammonium dicyanamides, ammonium benzoates and mixtures thereof
Implementation Method 2
carbon black; and b) a resin selected from the group consisting of a (meth)acrylate resin, a polyurethane resin, a silicone resin and mixtures thereof
Implementation Method 3
a stimulation or a sensing electrode comprising an ionically and/or electrically conductive pressure sensitive adhesive
Data Source
AI summary
The present invention relates to a stimulation or a sensing electrode comprising an ionically and/or electrically conductive pressure sensitive adhesive composition comprising a) an ionic liquid and/or carbon black; and b) a resin selected from the group consisting of a (meth)acrylate resin, a polyurethane resin, a silicone resin and mixtures thereof. The electrodes according to the present invention are used in skin applications transferring an electrical signal to the body via the skin or in skin applications as a contact medium as part of electrodes measuring bio-signals from the skin.