Viscous Ionic Liquid-Filled Wearable Elastomer with Positive Piezoconductivity

Abstract

Conductive elastomers based on full-filled structure have been widely used in soft electronics, such as wearable strain sensor for human motions detection. These elastomers are typically conductors because of the conductive fillers within elastic substrate, which can directly reflect the deformation via its separation during elongation. Nevertheless, most reported elastomers so far display a negative piezoconductive effect, i.e. the conductivity decreases under a tensile strain, which is undesirable since detecting the weak conductivity under large deformation is inconvenient. Here, we report a viscous ionic-filled elastomer comprising cellulose nanofibers and sodium chloride crystals, that exhibits an unconventional positive piezoconductive effect. Our elastomer uniquely possesses the worst conductivity ( σ : 0.28 S/m) in the relaxed state and increases rapidly when stretches due to the reversion of the cellulose nanofibers, namely “shutting effect”. Such a novel strain response mechanism has been achieved in other full-filled conductive elastomer, making it prospective in the advanced applications such as strain sensors, stretchable conductors, and smart robotics.

Keywords: ionic liquidpositive piezoconductivitywearable elastomerstrain sensor