Metal-Like Stretchable Nanocomposite Using Locally-Bundled Nanowires for Skin-Mountable Devices

Stretchable conductive nanocomposites have been intensively studied for wearable bioelectronics. However, development of nanocomposites that simultaneously feature metal-like conductivity(> 100 000 S cm^-1 ) and high stretchability (> 100%) for high-performance skin-mountable devices is still extremely challenging. Here a material strategy for such a nanocomposite is presented by using local bundling of silver nanowires stabilized with dual ligands (i.e., 1-propanethiols and 1-decanethiols). When the nanocomposite is solidified via solvent evaporation under a highly humid condition, the nanowires in the organic solution are bundled and stabilized. The resulting locally-bundled nanowires lower contact resistance while maintain their percolation network, leading to high conductivity. Dual ligands of 1-propanethiol and 1-decanethiol further boost up the conductivity. As a result, a nanocomposite with both high conductivity of ≈122,120 S cm^-1 and high stretchability of ≈200% is obtained. Such superb electrical and mechanical properties are critical for various applications in skin-like electronics, and herein, a wearable thermo-stimulation device is demonstrated.