Stretchable Electrode Sheet With Metal Particle Conductive Layer
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Solution Overview
Problem
Existing wearable biological information measurement devices face issues with maintaining electrical conductivity and durability when stretched, as conductive layers crack and resistivity increases, limiting their effectiveness and comfort during wear.
Innovation Solution
A sheet-like stretchable electrode comprising a first insulating layer and a stretchable conductor layer with a conductive filler and rubber, where the conductor layer has a resistance of 300 Ω/cm or less and can withstand 10% stretching with minimal load, ensuring high conductivity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive polymer-containing paint is applied to fabric to form a conductive layer, then electrical conductivity can be achieved, but cracks are produced when the fabric is stretched, resulting in interruption of electrical continuity
Solution Approach 1:
The patent changes the material parameters by using a conductive paste containing metal particles (silver, copper, or aluminum) suspended in a flexible polymer matrix instead of conductive polymer paint. This composition change allows the conductive layer to maintain electrical continuity while accommodating fabric stretching, as the metal particles remain electrically connected even when the flexible polymer deforms.
Solution Approach 2:
The patent creates a composite conductive layer by combining metal particles (conductive phase) with a flexible polymer matrix (structural phase). This composite structure provides both electrical conductivity through the metal particle network and stretchability through the flexible polymer, resolving the contradiction between maintaining electrical continuity and accommodating fabric deformation.
2Reliability
If the conductive layer is made thicker to achieve high electrical conductivity, then wiring conductivity improves, but the fabric cannot stretch properly and cracks form
Solution Approach 1:
The patent optimizes the thickness parameter of the conductive layer to a specific range (1-10 μm) that balances electrical conductivity and stretchability. Within this thickness range, the conductive layer maintains sufficient conductivity while remaining flexible enough to stretch with the fabric without cracking, resolving the trade-off between conductivity and stretchability.
Solution Approach 2:
The patent creates a conductive layer with non-uniform local properties by controlling the distribution and concentration of metal particles within the flexible polymer matrix. This allows regions of the conductive layer to have different degrees of conductivity and flexibility, enabling the layer to maintain overall conductivity while accommodating local deformations during fabric stretching.
3Ease of manufacture
If conventional wiring methods are used in wearable devices, then electrical functions can be implemented, but the devices become rigid and uncomfortable to wear
Solution Approach 1:
The patent replaces conventional rigid wiring structures with a flexible conductive layer formed as a thin film (1-10 μm) on the fabric surface. This thin flexible conductive layer maintains electrical functionality while conforming to the fabric's flexibility, eliminating the rigidity and discomfort associated with conventional wiring methods in wearable devices.
4Reliability
If conductive polymer paint is applied to fabric, then the fabric becomes conductive, but the paint permeates the fabric making it difficult to secure satisfactory thickness
Solution Approach 1:
The patent introduces a flexible polymer matrix as an intermediary carrier that holds metal particles on the fabric surface. This polymer matrix prevents the conductive material from permeating deep into the fabric while maintaining electrical conductivity through the metal particle network, allowing precise control of conductive layer thickness without paint permeation issues.
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 maintains high electrical conductivity and flexibility even after stretching, enhancing wear comfort and durability, allowing for reliable biological information measurement without significant resistance changes.
Implementation Method 1
the stretchable conductor layer comprises a conductive filler in an amount of 15 to 45% by volume and a resin in an amount of 55 to 85% by volume
Implementation Method 2
the resin contains at least a rubber containing a sulfur atom and/or a rubber containing a nitrile group
Data Source
Figure 1
AI summary
[Problem] The purpose of the present invention is to provide a stretchable electrode sheet and a stretchable wiring sheet that are capable of maintaining high electrical conductivity even if being stretched. [Solution] The stretchable electrode sheet and the stretchable wiring sheet of the present invention, wherein the electrode and the wiring are sheet-like and that are capable of being laminated on a substrate including; wherein the electrode has a first insulating layer and a stretchable conductor layer provided on the first insulating layer, and the wiring has a three-layer structure having the first insulating layer, the stretchable conductor layer, and a second insulating layer, and wherein the stretchable conductor layer has an electric resistance of 300 Ω/cm or less, and a load at stretching of a stretching rate of 10% of the electrode and the wiring is 100 N or less.