Snap‐Through–Driven Liquid Crystal Elastomers for High‐Power Remote Microneedle Actuation Toward Smart Livestock Systems

ABSTRACT

Generating rapid, high‐power mechanical impulses with light‐driven soft actuators remains challenging because photochemical deformation alone typically provides limited force and output power. Here, we report a magnetically assisted photoresponsive azobenzene‐containing liquid crystal elastomer actuator that converts light‐induced contraction into an amplified snap‐through impulse. By programming the liquid crystal alignment, a twisted nematic architecture with orthogonal surface directors was identified to maximize through‐thickness strain mismatch and the bending moment required for snap‐through. The optimized azobenzene‐containing LCE arch exhibited a peak velocity of 140 mm s ^{− 1} under purely light‐driven operation, confirming efficient photomechanical energy conversion; however, this response was insufficient for reliable microneedle penetration. Introducing magnetic bias lowered the instability threshold and amplified elastic energy release, increasing the peak velocity to 332 mm s ^{− 1} and yielding output powers approximately two orders of magnitude higher than previously reported liquid crystal‐based soft actuators. Leveraging this capability, SU‐8 microneedles were integrated onto the actuator to create a remotely triggered injection platform capable of penetrating skin‐mimicking gelatin phantoms and ex vivo porcine skin. These results establish a general strategy for high‐power soft actuation and non‐contact microneedle‐based physical intervention.