Wireless Power Transfer to Electrothermal Liquid Crystal Elastomer Actuators

Wirelessactuation of electrically driven soft actuatorsis ofparamount importance for the development of bioinspired soft roboticswithout physical connection or on-board batteries. Here, we demonstrateuntethered electrothermal liquid crystal elastomer (LCE) actuatorsbased on emerging wireless power transfer (WPT) technology. We firstdesign and fabricate electrothermal LCE-based soft actuators thatconsist of an active LCE layer, a conductive liquid metal-filled polyacrylicacid (LM-PA) layer, and a passive polyimide layer. LM can functionnot only as an electrothermal transducer to endow resulting soft actuatorswith electrothermal responsiveness but also as an embedded sensorto track the resistance changes. Various shape-morphing and locomotivemodes such as directional bending, chiral helical deformation, andinchworm-inspired crawling can be facilely obtained through appropriatelycontrolling the molecular alignment direction of monodomain LCEs,and the reversible shape-deformation behaviors of resulting soft actuatorscan be monitored in real-time through resistance changes. Interestingly,untethered electrothermal LCE-based soft actuators have been achievedby designing a closed conductive LM circuit within the actuators andcombining it with inductive-coupling WPT technology. When the resultingsoft actuator approaches a commercially available wireless power supplysystem, an induced electromotive force can be generated within theclosed LM circuit, which results in Joule heating and wireless actuation.As proof-of-concept illustrations, wirelessly driven soft actuatorsthat can exhibit programmable shape-morphing behaviors are demonstrated.The research disclosed herein can provide insights into the developmentof bioinspired somatosensory soft actuators, battery-free wirelesssoft robots, and beyond.