Temperature and locomotion dual self-sensing soft robots based on liquid crystal polymer foams†

Stimuli-triggered actuation and capability of sensing are two important prerequisites for self-sensing soft robots. Currently, liquid crystal polymer (LCP) based soft robots face difficulties in balancing the actuation and sensing in a single device. Here, a promising strategy is reported to design self-sensing robots using LCP foams, which perform actuation and self-sensing simultaneously after alignment and crosslinking. LCP foams are fabricated via controlled solvent vaporization, which feature open cell structures and high porosity, and maintain a reversible actuation strain of 40% in the LC mesogen alignment direction. The crosslinked liquid crystal elastomer foams (LCEFs) show temperature-sensitive resistance after incorporating ionic liquids inside the open cell channels and high tolerance to outside disturbance such as vibration due to the porous microstructure. In addition, the resistive signals during actuation cycles reflect the shape contracting and extending process of the LCEF actuators. Combining the light-triggered reversible actuation and self-sensing, the LCEF-based robot displays real-time feedback on its locomotion details (contraction, extension, and displacement) and temperature.