Stretchable Conductor with Surface Particle Concentration

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Solution Overview

Problem

Existing stretchable conductors face issues with high initial resistance values that increase significantly with extension, leading to potential breakage and limited extension degrees due to the dispersion of conductive materials in rubber, which compromises their durability and functionality in flexible electronics.

Innovation Solution

A stretchable conductor is developed using a fluororubber elastomer with scale-like conductive particles and a high-concentration surfactant aqueous solution, where the conductive particles are dispersed in a proportion of 400% or less by mass, and a phase-separation method is employed to create a partially porous structure with a high concentration of conductive particles on the surface, maintaining conductivity even under significant strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conductive particles are dispersed in rubber to create stretchable conductor, then stretchability is achieved, but initial resistance value becomes high and resistance increases significantly with extension

Engineering Contradiction:
ImprovestretchabilityVSAvoidconductivity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent combines rubber (elastomer) with conductive particles to form a composite stretchable conductor. This composite structure allows the material to exhibit both the elasticity of rubber and the conductivity of metal particles, resolving the contradiction between achieving stretchability and maintaining low resistance. The conductive particles form a network within the rubber matrix that maintains electrical connectivity even during deformation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent creates regions with different conductive particle concentrations within the stretchable conductor. By having higher conductive particle density in certain areas and lower density in others, the material optimizes both conductivity and stretchability locally. This non-uniform distribution allows the conductor to maintain low resistance while accommodating large deformations without particle aggregation or breakage.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If conductive particles are dispersed in rubber, then the conductor can be stretched, but the conductor becomes prone to breakage and has limited extension degree

Engineering Contradiction:
Improveextension degreeVSAvoiddurability
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The patent uses a rubber-based flexible matrix to embed conductive particles, creating a conductor that can undergo large deformations. The elastic nature of the rubber matrix allows the conductor to be stretched to several times its original length without breaking, while the embedded conductive particles maintain electrical connectivity through their flexible network structure.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent creates a dynamic conductor structure where the conductive particles can move and rearrange themselves during stretching and relaxation cycles. This dynamic behavior allows the conductor to adapt its internal structure during deformation, preventing particle aggregation and maintaining conductivity over repeated extension cycles, thereby improving durability.

Inventive Principle:
Principle #15Dynamics

3Reliability

If high concentration of conductive particles is used to reduce resistance, then conductivity improves, but the conductor becomes weaker and breaks more easily

Engineering Contradiction:
ImproveconductivityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent implements non-uniform distribution of conductive particles within the rubber matrix, with higher concentrations in regions requiring better conductivity and lower concentrations in regions requiring greater flexibility and strength. This local optimization allows the conductor to achieve low resistance without compromising mechanical integrity throughout the entire structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure where conductive particles are dispersed in a rubber matrix at optimized concentrations. The rubber matrix provides mechanical strength and flexibility, while the conductive particles provide electrical conductivity. This composite approach allows the material to simultaneously achieve good conductivity and mechanical strength, avoiding the weakness associated with high particle concentration.

Inventive Principle:
Principle #40Composite materials

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 provides a stretchable conductor with excellent conductivity and durability, capable of maintaining conductivity up to 200% strain, exceeding the performance of previous technologies, and suitable for integration in flexible devices and electronic skins.

Implementation Method 1

a phase-separation method is employed to create a partially porous structure with a high concentration of conductive particles on the surface

Methodology Applied
Scientific EffectPhase separation: Phase Change

Implementation Method 2

a stretchable conductor with excellent conductivity and durability, capable of maintaining conductivity up to 200% strain

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3104370B1Stretchable conductor, method for manufacturing same, and paste for forming stretchable conductor
Publication Date: 2021.05.19 THE JAPAN SCI & TECH AGENCY
  • EP3104370B1 patent drawingFigure 1
  • EP3104370B1 patent drawingFigure 2~3
  • EP3104370B1 patent drawingFigure 4~5

AI summary

A stretchable conductor of the present invention includes: a mixture which is configured of a stretchable portion made of an elastomer, and at least one type of conductive particles dispersed in the stretchable portion; and a conducting portion in which the conductive particles are aggregated in a higher concentration at one or a plurality of positions on an interface of the mixture than that at positions located in an inner portion of the mixture.