Wettability of liquid metals on PEDOT:PSS for soft electronics

Due to the high conductivity and flexibility of liquid metal, soft electronics are believed to be an ideal material for wearable electronics. However, high surface tension and surface oxides make it extremely challenging to load liquid metals onto flexible hydrophilic substrates. In this study, the excellent wettability of liquid metals on poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was systematically examined. This property was attributed to the synergistic effect of chemical and physical adhesion of liquid metals on PEDOT:PSS. By loading PEDOT:PSS onto a hydrophilic substrate, liquid metals were selectively adhered to the PEDOT:PSS region. As a result, a simple and high efficient PEDOT:PSS-assisted method for preparing liquid–metal soft electronics was developed. More intriguingly, highly conductive PEDOT:PSS after doping treatment still maintained outstanding wettability to liquid metals, favoring the realization of non-corrosive electrical connections between liquid metals and low cost electrode material (Cu). This PEDOT:PSS-assisted strategy can be used to fabricate various liquid metal-based electronics including soft circuits, paper electronics (1D), flexible sensors (2D), and conductive foams (3D), offering huge potential for flexible electronics and wearable sensors.