Swarm coordination of fish-like magnetic soft robots: directed aggregation and shape-adaptive attachment toward efficient drug delivery.

Miniature magnetic untethered soft robots offer promising opportunities for biomedical applications due to their tissue compatibility, functionalizable dimensions and flexible locomotion capabilities. However, their small size creates a mismatch between coverage area and lesion regions, limiting drug delivery efficacy. Here, inspired by natural fish migration and foraging behaviors, we present an approach to overcome these limitations through swarm coordination of fish-like magnetic soft robots. Individual robots with simplified designs for scalable production can perform constrained six-degrees-of-freedom fish-like maneuvers under an oscillating magnetic field and gradient magnetic field. By exploiting the unique property of the constant component of the oscillating magnetic field dominating the swimming direction when the actuation frequency approaches the robot's natural frequency, we achieved differentiated control of individual swimming directions under global magnetic field actuation through programming spatial distribution patterns of the constant field component. This enables our robotic swarm to demonstrate active spatial aggregation toward specific lesion areas and shape-adaptive attachment capabilities upon reaching the target. This work provides a new pathway for efficient therapeutic payload delivery to lesions through coordinated miniature magnetic soft robot swarms.