Gravity-independent self-rolling of liquid crystal elastomer rods via magnetically assisted photothermal actuation

Traditional self-rolling systems, which generally rely on gravitational moment or require multi-component assemblies, face limitations in microgravity actuation. In this study, we propose a gravity-independent self-rolling system wherein a liquid crystal elastomer rod embedded with a magnetic ring achieve self-sustained rolling on dual tracks above an iron plate via magnetically assisted photothermal actuation. Experiments under steady illumination confirm continuous rolling without gravitational support through magnetic force-coupling compensation. A theoretical framework integrating photomechanics and magnetic interactions derives governing equations predicting lateral curvature and driving moment. Theoretical derivation establishes that self-rolling initiates from photothermal lateral displacement derived from lateral curvature via geometric conversion, inducing magnetic force-coupling to generate continuous driving moment. Numerical simulations coupled with experimental validation demonstrate that angular velocity increases with both heat flux and track width due to augmented light-induced moment arm, but decreases with heat dissipation and friction-induced torque losses. This light-programmable system eliminates gravity dependence through contactless magnetic assistance, enabling applications in extraterrestrial robotics, space assembly operations, and microgravity-based devices.