Liquid crystal elastomer (LCE) has large and reversible deformation under stimulation, making it an ideal material for artificial muscles. Currently, multi-stimulus responsive LCE actually responds to each stimulus independently rather than responding to several stimuli simultaneously. Achieving an enhanced effect from concurrent stimuli is still a challenge, which requires a new stimulus-response mechanism. This work develops a novel and facile solvent evaporation-assisted template method to prepare LCE hollow fiber (LCEHF) with axial alignment. Taking advantage of the enhanced effect of heat-induced phase transition and mechanical force-induced orientation transition of mesogens, the LCEHF under both heat and pressure can produce a large contraction ratio of ≈50%, which is higher than 42% of thermal stimulation or 27% of pneumatic stimulation. It can also enhance the respective response and recovery speed of LCEHF to 300 and 3700 times of pneumatic actuation. Additionally, the enhanced effect lowers the actuation temperature much below the phase transition temperature, imparting LCEHF with high mechanical performance during actuation. Furthermore, the dual thermal-pneumatic responsive LCEHF can mimic human biceps and cause large and rapid bending of an artificial arm reversibly. This new actuation methodology sheds new light on improving LCE actuation performance and broadens its application scenarios.
Smart adhesion actuators have played an increasingly important role in industrial manufacturing, medical equipment, and other applications of daily life. Inspired by the octopus sucker, a smart bionic adhesion actuator is designed that uses hydrogel-based materials with a photothermal effect to simulate the contraction and relaxation of octopus sucker muscles, enabling it to rapidly grasp and release objects weighing more than 24 times its own weight, while having good cyclic stability. The magnitude of the grasping force can be monitored in real time through an additional sensing structure, which is similar to the nerves of octopus sucker. By sensing and adjusting the state of adsorption, controllable adsorption can be achieved using this self-sensing function, thereby greatly improving energy efficiency. It provides a new direction for the design of smart bionic adhesion actuators with hydrogels.
Wenxin Fan,Caiyun Shan,Hongyu Guo,Jianwei Sang,Rui Wang,Ranran Zheng,Kunyan Sui,Zhihong Nie
The design of materials that can mimic the complex yet fast actuation phenomena in nature is important but challenging. Herein, we present a new paradigm for designing responsive hydrogel sheets that can exhibit ultrafast inverse snapping deformation. Dual-gradient structures of hydrogel sheets enable the accumulation of elastic energy in hydrogels by converting prestored energy and rapid reverse snapping (<1 s) to release the energy. By controlling the magnitude and location of energy prestored within the hydrogels, the snapping of hydrogel sheets can be programmed to achieve different structures and actuation behaviors. We have developed theoretical model to elucidate the crucial role of dual gradients and predict the snapping motion of various hydrogel materials. This new design principle provides guidance for fabricating actuation materials with applications in tissue engineering, soft robotics, and active medical implants.
危险品化学品经营许可证（带存储）