Multi-stimulus responsive and durable liquid crystal elastomer fiber actuators for artificial muscles and...

Liquid crystal elastomer (LCE) fiber actuators are pivotal for advancing artificial muscles and soft robotics, yet the current state-of-the-art suffers from limited driving modalities and inadequate long-term stability under photo-electrical stimulation. Herein, we report a novel core-shell indium tin oxide (ITO)@MXene/LCE composite fiber actuator fabricated via a combined two-step crosslinking template method and magnetron sputtering technology. The resultant composite fiber exhibits a well-defined core-shell structure with uniform ITO coating on the MXene/LCE surface and robust core-shell interface adhesion. This advanced actuator demonstrates efficient multi-stimuli responsiveness to heat, near-infrared light, and electricity, achieving remarkable reversible contraction (>45%), rapid response speed, and effective actuation under low voltage (3.0 V) Joule heating. It also possesses excellent mechanical strength and outstanding cyclic actuation durability, maintaining stable performance over 1000 driving cycles with intact ITO layer adhesion. For proof-of-concept, two prototypes are constructed: a photo-driven bionic tibialis anterior muscle simulating leg swinging with a peak speed of ∼600 cm/s and angle range of ∼70°, and a reconfigurable emergency circuit switch enabling autonomous on-off control via electrothermal contraction (overvoltage disconnection) and reversible cooling reset. The switch leverages electrothermal contraction to autonomously physically disconnect the circuit under overvoltage conditions and reversibly resets upon cooling, demonstrating reliable protection stability over 300 consecutive triggering cycles. This work lays a solid material foundation for high-performance, multifunctional integrated actuators required for next-generation intelligent systems.