Wireless Power Transfer to Electrothermal Liquid Crystal Elastomer Actuators

Abstract

Wireless actuation of electrically driven soft actuators is of paramount importance for the development of bioinspired soft robotics without physical connection or on-board batteries. Here, we demonstrate untethered electrothermal liquid crystal elastomer (LCE) actuators based on emerging wireless power transfer (WPT) technology. We first design and fabricate electrothermal LCE-based soft actuators that consist of an active LCE layer, a conductive liquid metal-filled polyacrylic acid (LM-PA) layer, and a passive polyimide layer. LM can function not only as an electrothermal transducer to endow resulting soft actuators with electrothermal responsiveness but also as an embedded sensor to track the resistance changes. Various shape-morphing and locomotive modes such as directional bending, chiral helical deformation, and inchworm-inspired crawling can be facilely obtained through appropriately controlling the molecular alignment direction of monodomain LCEs, and the reversible shape-deformation behaviors of resulting soft actuators can be monitored in real-time through resistance changes. Interestingly, untethered electrothermal LCE-based soft actuators have been achieved by designing a closed conductive LM circuit within the actuators and combining it with inductive-coupling WPT technology. When the resulting soft actuator approaches a commercially available wireless power supply system, an induced electromotive force can be generated within the closed LM circuit, which results in Joule heating and wireless actuation. As proof-of-concept illustrations, wirelessly driven soft actuators that can exhibit programmable shape-morphing behaviors are demonstrated. The research disclosed herein can provide insights into the development of bioinspired somatosensory soft actuators, battery-free wireless soft robots, and beyond.

Biomimetic Actuator Based on the Evasion Behavior of Pillbugs in Liquid Crystal Elastomers

“…Notably, among these stimuli, light emerges as an outstanding option owing to its ubiquity and the potential for precise remote manipulation. In recent years, these smart materials have discovered a broad spectrum of applications in soft robotics, 8,9 biomedical, 10,11 and biomimetic devices. 12 In contemporary times, commonly utilized wireless-controlled smart materials comprise hydrogels, 13−15 shapememory alloys, 16−18 dielectric elastomers, 19−21 and liquid crystal elastomers 22−24 (LCEs).…”

“…Notably, among these stimuli, light emerges as an outstanding option owing to its ubiquity and the potential for precise remote manipulation. In recent years, these smart materials have discovered a broad spectrum of applications in soft robotics, , biomedical, , and biomimetic devices …”

Electrostatically Powered Multimode Liquid Crystalline Elastomer Actuators

“…Soft actuators employing a range of elastomers have garnered attention due to their remarkable adaptability and dynamic responsiveness to a multitude of stimuli. − Especially, liquid crystal elastomers (LCEs) have gained significant attention in the recent past because of growing interest in their programmable and reversible shape-changing properties when exposed to various stimuli and the potential applications in soft robots, artificial muscles, sensors, mechanical damping, and aerospace systems. − LCEs combine the unique anisotropic properties of the liquid crystals (LCs) and the entropic elasticity of the polymer. − In particular, the exotic molecular orientation of the LC mesogens within the lightly cross-linked polymer network is promising for converting external stimuli, such as heat, light, and magnetic or electrical fields, into mechanical work. − The stimuli response of the LCEs is ascribed from anisotropic deformation induced by the phase transition of LCs. The overall molecular order is sterned by the collective orientation of the LC mesogens in the polymer network by prealignment of LCEs. − It could further amplify the stimuli response and shape morphing, including bending, coiling, twisting, and complex three-dimensional morphing configurations if prepared pixelated or voxelated.…”

Triple-Responsive Soft Actuator with Plastically Retentive Deformation and Magnetically Programmable Recovery

“…In recent years, thermally responsive actuators have attracted increasing interest due to their capability of exhibiting large-volume shape changes and enabling various actuation mechanisms. Such actuators can respond to various heat-generating methods such as joule heating, , photothermal heating, , and magnetocaloric effects . However, conventional thermally responsive soft actuators are actuated by the difference in the thermal expansion coefficients of the actuation materials.…”