Development of Electronic Fibers That Function Well Even When Length Increased by 150%

KAIST Research Team Utilizes Liquid Metal Materials

Domestic researchers have developed electronic fabric that functions even when stretched extensively.

KAIST announced on the 25th that a joint research team led by Professors Steve Park from the Department of Materials Science and Engineering, Jae-woong Jung from the Department of Electrical Engineering, and Sung-joon Park from the Department of Bio and Brain Engineering developed highly stretchable electronic fibers using a liquid metal composite with high conductivity and durability.

Electronic fibers are considered a key element in user-friendly wearable devices, healthcare devices, and minimally invasive implantable electronic devices, which have recently gained attention, and active research is underway. However, when attempting to stretch electronic fibers using solid metal conductive fillers, their electrical conductivity rapidly decreases, resulting in degraded electrical properties.

To solve the problem of electronic fibers not stretching, the research team proposed a conductive filler based on liquid metal particles that can deform according to mechanical deformation rather than having a fixed solid shape. When tensile force is applied, the liquid metal microparticles elongate into an elliptical shape, minimizing changes in electrical resistance. However, since their size is several micrometers, it is impossible to coat fibers using simple methods like dip-coating, which have been used previously.

The research team addressed this by developing a new method called suspension shearing, which allows liquid metal particles to be delivered densely onto fibers and chemically bonded to the fibers by changing the composition of the suspension in real-time between the blade and substrate. Additionally, by further coating the liquid metal particles with carbon nanotubes (CNTs) that have excellent mechanical stability, the mechanical stability of the liquid metal composite was also secured.

The produced stretchable electronic fibers exhibited excellent initial conductivity (2.2x10^6 S/m) without requiring additional processing, and unlike conventional fibers based on solid metal conductors, showed almost no change in electrical resistance even when stretched by 150%. They also demonstrated excellent mechanical stability, maintaining electrical properties through repeated deformation tests, and could be easily integrated with various electronic components. The research team implemented various electronic circuits on commercially available clothing using these fibers.

Furthermore, since the coating method for the liquid metal composite is compatible with various fibers and the materials have excellent biocompatibility, the team realized fiber-type bioelectronic fibers for neuroscience research. Using the proposed coating method, they fabricated brain activity electrodes, neural stimulation electrodes, and multifunctional optogenetic probes that are unaffected by mechanical deformation, demonstrating broad versatility and high process reliability.

The research results were published online on the 13th in the international journal Nature Communications.

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