Stretchable Conductive Wiring for Wearable Devices
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Solution Overview
Problem
The challenge lies in creating a wearable smart device with stretchable electrical wiring that maintains conductivity and durability while being integrated into garments, as existing methods face issues with precision on uneven fabric surfaces, heat resistance, and discomfort due to thick wiring and sagging during the curing process.
Innovation Solution
A stretchable conductor composition with a high percentage of conductive particles and a non-crosslinked elastomer, combined with a solvent of high boiling point, is used to form a wiring with a narrow line interval and width, allowing for low-temperature drying and improved flexibility and resistance to stretching, bending, and twisting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal foil is used to form electrical wiring on stretchable garments, then conductivity is achieved, but the garment becomes uncomfortable due to thick wiring and the metal foil undergoes permanent plastic deformation during washing
Solution Approach 1:
The patent changes the material parameters from rigid metal foil to flexible polymer-based conductive composite. The conductive polymer matrix with embedded conductive particles maintains electrical conductivity while providing the flexibility and stretchability needed for comfortable garment wear, eliminating the permanent deformation issues of metal foil.
Solution Approach 2:
The patent uses a composite material system consisting of a polymer matrix combined with conductive particles. This composite approach allows the wiring to exhibit both electrical conductivity and mechanical flexibility, resolving the contradiction between maintaining conductivity and ensuring wearing comfort during repeated washing and stretching.
2Adaptability or versatility
If conventional conductive paste with crosslinked elastomer is used, then stretchability is achieved, but the wiring sags during high-temperature curing and dimensional precision is lost
Solution Approach 1:
The patent changes the curing temperature parameter from high temperature to low temperature processing. This prevents the sagging and deformation that occurs during high-temperature curing of crosslinked elastomers, while still achieving the desired stretchability through the polymer matrix structure and conductive particle arrangement.
3Reliability
If high-temperature curing is used to dry conductive paste, then complete solvent evaporation is achieved, but the garment substrate is damaged and wiring deformation occurs
Solution Approach 1:
The patent changes the drying temperature parameter from high temperature to low temperature processing. This prevents damage to the garment substrate and wiring deformation while still achieving sufficient solvent evaporation through extended drying time and optimized paste formulation with appropriate solvent selection.
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 results in a wearable smart device with enhanced washing resistance, reduced discomfort, and improved durability, maintaining electrical continuity even after repeated elongation, while allowing for fine line patterns and reduced solvent residue.
Implementation Method 1
a solvent of high boiling point, is used to form a wiring with a narrow line interval and width, allowing for low-temperature drying and improved flexibility and resistance to stretching, bending, and twisting
Data Source
AI summary
The present invention provides to a wearable smart device having electrical wiring comprising a stretchable conductive composition having excellent in durability such as repeated bending properties and repeated twisting properties, a material for realizing the wearable smart device, and a method for producing the wearable start device.An electrical wiring including a fine line having an electrical line interval of 1 mm or less, preferably the line width of less than 1 mm, is formed by printing a paste for forming a stretchable conductor containing metal-based conductive particles and a non-crosslinked elastomer, and further dried and cured at a low temperature condition of 120° C. for 30 minutes. As a result, the wearable smart device having electrical wiring constituted by fine lines without sagging of the edge is obtained.