Phototunable adaptive colloidal microrobots in a nematic liquid crystal
Phys. Rev. Applied 25, 014066 – Published 28 January, 2026
DOI: https://doi.org/10.1103/rzmj-dhtc
Abstract
Colloidal microrobots actuated by external stimuli often exhibit complex locomotion that is reminiscent of biological microswimmers. We investigate the electrophoretic transport of metallodielectric Janus microspheres functionalized with a UV-responsive photoactive dendrimer suspended in a nematic liquid crystal. By synergistically combining ultraviolet (UV) illumination and electric-field actuation, we achieve dynamic control of particle motion. The UV-induced conformational changes in the dendrimer trigger particle rotation and reversible transformations of associated topological defects, alternating between boojum and Saturn-ring configurations during cyclic UV exposure. This defect switching mediates transitions between pusher and puller swimming modes, resulting in abrupt changes in particle’s trajectories. These photoactive Janus microrobots demonstrate enhanced motional versatility and stochastic dynamics, including run-and-tumble-like behaviors that mimic adaptive navigation strategies found in living microorganisms. Our findings highlight the promise of multi-stimuli-responsive colloidal microrobots for microscale transport and studies of active matter in anisotropic soft environments.
