Interfacing\nLiquid Metals with Stretchable Metal Conductors

Abstract

Highly stretchable conductors are\nessential components in deformable\nelectronics. Owing to their high stretchability and conductivity,\nliquid metals have attracted significant attention for use as circuits\nand interconnections. However, their poor wettability to stretchable\nmetal electrodes prevents the formation of stable electrical connections.\nThis study examined two approaches for creating a stable interface\nbetween a liquid metal (EGaIn) and stretchable metal electrodes via:\n(i) the use of honeycomb-structured stretchable metal electrodes and\n(ii) the addition of a conducting polymer interlayer. The line width\nof the honeycomb had a significant influence on the formation of a\nstable interface. The liquid metal formed a stable film layer on honeycomb\nmetal electrodes, which have line widths of less than 50 μm.\nCoating PEDOT:PSS with a nonionic surfactant lowered the interfacial\nenergy of EGaIn with flat stretchable metal surfaces; hence EGaIn\nwas coated uniformly on the stretchable metal surfaces. Strain sensors\nwere fabricated as a demonstrative example of an application that\nutilizes the stable interface.