Integration of multiple functions into a simple unit can simplify the device design and facilitate the miniaturization and portability of soft robots. Actuating and sensing functions are the basis of soft robots to interact with the environment. In this work, a modified melt-spinning method is used to produce liquid crystal elastomer (LCE) fibers with a hollow structure and fill the core with liquid metal (LM) to construct LCE–LM coaxial fibers with integrated sensing and actuation functions. The inner LM generates Joule heat upon an electrical trigger to actuate the outer LCE shell. When LCE–LM coaxial fibers are actuated or loaded with objects, the deformation of LCE shell forces the inner LM to reform, allowing to sense the motion of the fibers or the mass of objects, by measuring the feedback voltage or resistance change of the inner LM. Benefitting from the material selection and structural design, the LCE–LM coaxial fibers with integrated actuating and sensing capability exhibit large reversible contraction (40%) and reliable durability (5000 cycles for actuation and motion sensing). Finally, a soft three-arm Delta robot is fabricated to complete object identification, sorting tasks, and in situ monitoring the motion process.
Liquid crystal elastomer (LCE) fibers are capable of large and reversible deformations, making them an ideal artificial muscle. However, limited to stimulating source and structural design, current LCE fibers have not yet achieved both large contraction ratio and fast contraction rate to perform the intense motion. In this work, electrothermal-responsive liquid metal (LM) containing LCE (LM-LCE) fibers is reported. By introducing flexible liquid metal, LM-LCE fibers retain deformability with a large contraction ratio similar to that of pure LCE fibers and are endowed with electrical responsiveness. Applying precisely controlled electrical stimulation, the contraction ratio and rate of LM-LCE fibers can be programmed by adjusting voltage value and pulse time. Under electrical stimulation at 1.25 V cm −1 , 0.1 s, LM-LCE fibers can produce over 40% contraction ratio at an ultrafast contraction rate of up to 280% s −1 . Furthermore, LM-LCE fibers mimic human triceps muscle and can conduct precise ball shooting. LM-LCE fibers with excellent contraction ratio and rate extend their functionality as artificial muscles to perform intense movements and are expected to enrich the challenging applications of soft robots.
Yunpeng Wang,Wei Liao,Jiahao Sun,Rajib Nandi,Zhongqiang Yang
Human muscles, including skeletal, smooth, and cardiac muscles, are able to perform diverse deformations and execute complex biofunctions stimulated by nerve signals. Similarly, liquid crystal elastomer (LCE), which can respond to external stimuli with large and reversible deformations, demonstrates superior advantages to mimic nature muscles to fabricate artificial muscles. Till now, LCE has been utilized to simulate deformations and related functions of skeletal and smooth muscles. However, limited by the existing fabrication strategy, employing LCE to mimic the motion of cardiac muscles and further realizing the structure-determined pumping functions, is still an open challenge. Learning from the specific spatial arrangements and synergistic actuation of cardiac muscle fibers within human heart, a simple and general strategy to construct artificial cardiac muscles with LCE fibers is proposed. In this work, LCE fibers with similar modulus and actuation behavior to muscle fibers are fabricated and spatially arranged in biological architectures as cardiac muscle fibers. As a result, artificial cardiac muscles are constructed and are able to perform simultaneous contraction and torsion motions, realizing heart-pumping functions. This general strategy should be also applicable for other smart materials to conduct challenging tasks.
危险品化学品经营许可证（带存储）