Leveraging Phototactic Effects in Liquid Crystal Polymers for Model-Informed Actuation

Phototactic soft robotic systems can be controlled without the need for tethers through strategic manipulation of light-matter interfaces. Here, we introduce a novel phototactic soft actuator, LUMA (Light-responsive Untethered Model-informed Actuator), comprising liquid crystal polymers (LCPs) that are activated by divergent directional light. Systematic characterization of the bending behaviors of LCPs revealed tunable photophobic and phototropic responses dependent on incident illumination angle, intensity, and the design of light shields. We developed a predictive computational model, the Photo-Thermal-Mechanical (PTM) model, to capture complex deformation dynamics and enable the programming of intricate actuation profiles. Leveraging divergent light actuation and informed by the PTM model, we designed LUMA soft robots, including crawlers capable of reversible bidirectional motion and cargo delivery systems with controlled projectile trajectories. This investigation establishes design principles and modeling frameworks for harnessing diverse illumination profiles, enabling programmable and predictable phototaxis in soft robotic systems through strategic light-matter coupling. The innovative approach provides intuitive yet precise manipulation capabilities, advancing the field of phototactic soft robotics.