Multifunctional miniature robots: Harnessing the photothermal effect of magnetic microparticles for light and magnetic control

Developing miniature robots with multimodal mobility in complex environments remains challenging. This study developed miniature robots based on magnetic particle-doped liquid crystal elastomers (LCEs) that integrate multicomponent functional doped materials and LCE molecular orientation engineering. Thanks to the synergistic introduction of magnetic particles with photothermal effects and 5CB plasticizer, the robot exhibits fast photothermal response in both terrestrial and underwater environments. In the terrestrial environment, the designed photomagnetic dual-field coupling strategy reshapes the physical boundaries of robots, improving their obstacle-crossing ability and achieving asymmetric full-orientation dual-mode jumping. In the underwater environment, the robot utilizes frequency laser flapping to induce wake vortex rings to overcome moderate Reynolds number drag. Especially, by utilizing the spatial resolution of the local light field, it successfully achieves efficient directional propulsion and flexible steering control by switching the irradiation position to break fluid symmetry, substantially alleviating the spatial-control limitations of globally applied magnetic fields. Finally, we demonstrated potential applications of designed miniature robots on targeted photothermal therapy of cancer cells with high accuracy. We expect that the newly developed dual-responsive and multifunctional miniature robots will find broad medical applications, such as targeted drug delivery and minimally invasive surgery.