Living cilia stir, sweep, and steer via swirling strokes of complex bending and twisting paired with distinct reverse arcs. Efforts to mimic their dynamics rely on multi-material designs, since programming arbitrary motion is difficult in single materials.
A team at the Harvard MRSEC led by Bertoldi and Aizenberg has developed an approach to achieve a diverse trajectories from a single-material system via self-regulation: when a photoresponsive liquid crystal elastomeric pillar with mesogen alignment is exposed to light, it ‘dances’ dynamically as light initiates a traveling order-to-disorder transition front that twists and bends via opto-chemo-mechanical feedback. Guided by a theoretical model, a wide range of trajectories are realized by tailoring light illumination, molecular anisotropy, and geometry. Furthermore, higher order dynamics emerge in micro-pillar arrays and jointed geometries, with broad implications for autonomous actuators used in soft robotics, biomedical devices, and energy transduction materials.