Multimodal Locomotion and Dynamic Interaction of Hydrogel Microdisks at the Air–Water Interface under Magnetic and Light Stimuli

The potential applications of hydrogel microrobots in biomedicine and environmental exploration have sparked significant interest in understanding their behavior under multiphysical fields. This study explores the multimodal locomotion and dynamic interaction of hydrogel microrobots at the air–water interface under magnetic and light stimuli. A pair of hydrogel microrobots at the air–water interface exhibits a transition from cooperative, combined rotation to interactive behavior, involving both rotation and revolution under the influence of a rotating magnetic field (RMF), and a shift from attraction to separation under near-infrared (NIR) light, demonstrating the dynamic modulation of their behaviors in response to different stimuli. Notably, the behavioral patterns of multiple hydrogel microrobots under multiphysical fields indicate that NIR light can enhance interactive motion behaviors under RMFs and extend the range of motion trajectories. Dynamic models for each condition are established and analyzed based on dynamic equilibrium, and their behavior can be modulated by parameters such as magnetic particle concentration, magnetic field frequency, and NIR light intensity. This work introduces a novel strategy for regulating and controlling the dynamic behaviors of hydrogel microrobots, offering new insights into their multiphysical field locomotion.