Multimodal Actuation and Precise Control in Liquid Crystal Elastomer Optical Fiber Artificial Muscles.

Artificial muscles mimicking the fibrous structure and functionalities of natural skeletal muscles have garnered substantial interest for applications in actuators, soft robotics, and biomedical devices. However, achieving multidirectional actuation and delicate manipulation in confined environments remains challenging. Inspired by the neuromuscular system, a novel liquid crystal elastomer optical fiber (LCEOF) is introduced as artificial muscle with multimodal actuation and precise control. Fabricated through a two-step process, the LCEOFs possess sufficient orientation order (0.65) and low optical transmission loss (0.37 dB cm), enabling over 40% contraction strain with minimal ambient interference. Bundling multiple LCEOFs yields artificial arms capable of complicated and controllable deformations, including long-distance contraction (≥5 cm), weightlifting (>4000 times their own weight), wide-range torsion (0-180°), and omnidirectional bending (0-360°). Multimodal actuation is precisely and independently regulated via terminal-coupled laser inputs for each LCEOF in bundled arrays, enabling coordinated, crosstalk-free motions. These optical fiber artificial muscles allow precise and controllable operation of an artificial hand for grasping and manipulating objects, without reliance on free-space lateral illumination. Additionally, robotics systems incorporating bundles of LCEOFs have been designed and demonstrated for tasks such as laser writing and object transfer in confined environments, thereby offering new possibilities for the advancement of smart actuators.