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Advanced Materials Interfaces, 9(35), 2201693.

https://onlinelibrary.wiley.com/doi/full/10.1002/admi.202201693

■ Researchers

Kwangseok Park

Department of Mechanical Engineering, KAIST

Kwangseok Park, Jeongsu Pyeon, Seung Hee Jeong, Yong-Jin Yoon, Hyoungsoo Kim

■ Abstract

Self-sinterable gallium-based liquid metal (LM) ink for a handy drop-casting coating method is developed. The fabricated LM electrode is coffee-ring-free and bilayer-free, which guarantees high electrical conductivity, wettability, flexibility, and stretchability. The ink consists of Galinstan, ethanol-water mixture, hydrochloric acid, and polyvinylpyrrolidone. The binary mixture provides excellent wetting conditions and suppresses a coffee-ring stain from Marangoni mixing. The acid removes an oxide layer on the LM interface. The colloidal interaction forces by self-assembled polyvinylpyrrolidone induce avalanche coalescences of the particles at the end of evaporation, which produces a thin and uniform dried conductive layer. The acid and polymer provide a bilayer-free structure and electrification without any post sintering. The drop-casted self-transformed LM electrode showed excellent electrical resistance of O (0.1–1 Ω) on folding and stretching conditions. It is believed that this method can serve as flexible and stretchable electrodes, on various substances for soft robots and wearable devices, without any complicated post-process.

• Liquid Metal
• Particles
• Flexible
• Stretchable Electrodes

• [M-Terview] 김형수 교수(KAIST 기계공학과)