Shape-programmable, deformation-locking, and self-sensing artificial muscle based on liquid crystal elastomer and low–melting point alloy

Abstract

An artificial muscle capable of shape programmability, deformation-locking capacity without needing continuous external energy, and self-sensing capability is highly desirable yet challenging in applications of reconfigurable antenna, deployable space structures, etc. Inspired by coupled behavior of the muscles, bones, and nerve system of mammals, a multifunctional artificial muscle based on polydopamine-coated liquid crystal elastomer (LCE) and low–melting point alloy (LMPA) in the form of a concentric tube/rod is proposed. Thereinto, the outer LCE is used for reversible contraction and recovery (i.e., muscle function); the inner LMPA in the resolidification state is adopted for deformation locking, and that in the melt state is adopted for angle variation monitoring by detecting resistance change (i.e., bones and nerve functions, respectively). The proposed artificial muscle demonstrates multiple performances, including controllable bending angle, position, and direction; deformation locking for supporting heavy objects; and real-time monitoring of angle variation, which also provides a straightforward and effective approach for designing soft devices.

Advances in artificial muscles: A brief literature and patent review

“…In the last 2 years, the performance metrics of artificial muscles have been upgraded and have continued to gain new applications in the field of soft robotics. We can see the refinement of artificial muscle powered insect-sized robots ( Wang Z et al, 2021 ; Kim D et al, 2022 ), the improvement of artificial muscle driven water-walking robots ( Zhou X et al, 2021 ; Kim S et al, 2022 ), soft tension robots for exploring unknown spaces ( Kobayashi et al, 2022 ; Zhou et al, 2022a ), the enhancement of artificial muscle driven soft crawling robots ( Liu et al, 2021 ; Wu et al, 2022 ), the realization of rehabilitation assistance training robot based on pneumatic artificial muscles ( Wang and Xu, 2021 ; Chu et al, 2022 ; Tsai and Chiang, 2022 ), control optimization and modeling of artificial muscle-actuated endo-exoskeleton robots ( Chen et al, 2022 ; Lin et al, 2021 ; Liu H et al, 2022 ; Yang et al, 2022 ), and the application of SNA in soft wearable robots ( Jeong et al, 2022 ).…”

Reconfigurable scaffolds for adaptive tissue regeneration

“…LCEs, with stimuli-responsive shape-morphing properties, have demonstrated great promise for the applications of actuation, 68–70 soft robotics, 71–73 and controllable drug delivery. 74–76 In the field of tissue engineering and regenerative medicine, LCEs have also received intensive attention first because of their biomimetic architectures.…”

Recent advances in molecular programming of liquid crystal elastomers with additive manufacturing for 4D printing

“…With unique characteristics including stimuli-responsive deformation, anisotropic properties, and soft elasticity, LCEs offer great promise in many fields such as soft robotics, 82,83 electronics, 84,85 and smart devices. 86,87 However, relatively plane geometries (e.g.…”