Highly conductive and stretchable hydrogel using a percolated network of whiskered gold nanosheets

Abstract Conductive and stretchable hydrogels (CSHs) are promising materials for soft bioelectronics. However, hitherto developed CSHs suffer from unsatisfactory electrical conductivity and stretchability. As the electrical properties of a CSH are determined by the type of conductive components and the quality of their percolation, a breakthrough in these factors is required for the high performance CSH. Here, we developed CSHs including a percolated network of whiskered gold nanosheets (wAu-CSHs). A high fraction of whiskered gold nanosheets (> 3 vol.%) is impregnated in the hydrogel matrix through a sequential formation process of the gold nanomaterial network and the hydrogel matrix. This wAu-CSH fabrication method is applicable to various hydrogels includingpolyacrylamide, polyacrylic acid, and polyvinyl alcohol, and even to an organogel such as polybutyl acrylate. Regardless of the types of hydrogels, the wAu-CSH exhibits a conductivity of ~ 500 S/cm and a maximum strain of ~ 300 % evenwithout any supporting substrate. We increased the density of the gold nanomaterial network through a pressing process to maximize the conductivity of wAu-CSHs,exhibitinga high conductivity of ~ 3300 S/cm and a maximum strain of ~ 100% with a supporting hydrogel layer.