All-soft material system for strong soft actuators

In this paper, we present an improvement to a recently developed thermally responsive silicone-based actuator. The actuator is made of silicone with dispersed solvent droplets and expands when the droplets undergo a liquidgas phase transition, which is achieved at low voltages using an embedded Joule heater. In previous work, the embedded heater was a nickel-chromium spiral-shaped Joule heating wire. In the present work, we replace the wire with a silicone-based conductive composite to create a fully soft actuator. We characterize the thermal response of the conductive composite for Joule heating the actuator and the blocked force of the actuator when implemented as a McKibben-like muscle. From this, we show that the conductive composite performs as well as the original wire heater, with improved material compatibility. Finally, we demonstrate a 20 g silicone actuator embedded with the conductive composite lifting its 4.3 kg DC power source.