Conductive Material Using Metal Nanowire Bundles for Extensible Transducers
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Solution Overview
Problem
Conventional conductive materials for deformable electronic parts, such as transducers, face challenges in maintaining conductivity and durability due to aggregation of metal nanowires and increased electrical resistance upon extension, which limits their extensibility and performance.
Innovation Solution
A conductive material comprising a polymer with a glass transition temperature of 25°C or below and metal nanowires assembled into wire bundle portions dispersed within the polymer, which increases contact points between nanowires, preventing pathway breakage and maintaining conductivity during deformation, while also using a washing process to remove hydrophilic polymers and incorporating additional metal fillers for enhanced conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal nanowires are dispersed independently in polymer, then conductivity pathways can be formed, but the number of contact points between nanowires is decreased and electrical resistance increases upon extension
Solution Approach 1:
Multiple metal nanowires are merged into bundles where they are closely associated with each other, increasing the number of contact points between nanowires within the bundle. This merging approach maintains conductivity pathways while providing redundant contact points that prevent resistance increase during extension.
2Shape
If silver nanowires with polyvinylpyrrolidone are mixed in polymers, then nanowire growth direction is controlled, but the silver nanowires aggregate to form large aggregates and conductive pathways cannot be sufficiently formed
Solution Approach 1:
The patent creates local conductive regions where wire bundle portions are densely packed to provide sufficient conductivity, while allowing non-conductive polymer regions to exist between these local conductive zones. This local quality approach ensures conductive pathways are sufficiently formed without requiring complete coverage.
3Reliability
If aspect ratios of metal fillers are increased to increase contact points, then conductivity can be maintained upon extension, but there is a limitation to make metal filler thinner at present
Solution Approach 1:
The patent uses composite structures combining metal nanowires with polymer materials to create wire bundle portions. This composite approach allows the use of nanowires with achievable aspect ratios while maintaining conductivity through the bundled configuration, avoiding the need to further thin metal fillers beyond current manufacturing limitations.
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 highly extensible conductive material with stable electrical resistance and improved durability, ensuring the transducer's performance is not significantly compromised by deformation, and the material is less prone to cracking and destruction.
Implementation Method 1
wire bundle portions each formed by assembling the metal nanowires
Implementation Method 2
a polymer having a glass transition temperature (Tg) of 25°C or below
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A conductive material according to the present invention includes a polymer having a glass transition temperature (Tg) of 25°C or below and a metal filler containing metal nanowires; and a structure in which wire bundle portions each formed by assembling the metal nanowires are dispersed in the polymer. The conductive material according to the present invention includes the wire bundle portions, in each of which the metal nanowires are assembled. Accordingly, the conductive material is highly extensible, and electrical resistance is not easily increased upon extension. A transducer according to the present invention includes a dielectric layer made of an elastomer, a plurality of electrodes with the dielectric layer interposed therebetween, and wirings each connecting to corresponding one of the electrodes. Either one or both of the electrodes and the wirings are formed of the conductive material.