Multiple cilia-like swarms enable efficient microrobot deployment and execution

Magnetic microrobot swarming strategies are promising methods to overcome the complex tasks that are almost impossible for a single microrobot, demonstrating stunning performances ranging from cargo delivery to medical detections. However, it is hard for microrobot swarms to navigate and perform assignments when confronted with a sophisticated environment, such as uneven surfaces. Herein, we report a strategy that organizes μm-sized magnetic microrobot swarms into mm-height cilia-like structures through oscillation and homogeneous magnetic fields. It enables more powerful capabilities of passing obstacles and achieving flexible deployment and other functionalities. Related physical analysis, simulation, and experimental results reveal that the size of microrobot swarms can be controlled by regulating the applied magnetic actuation fields. Finally, the microrobot swarms have been successfully deployed in biological tissues of 3 mm in height to greatly enhance laser ablation efficiency. The proposed method offers a solution to deploy microrobot swarms in extreme environments, advancing next-generation therapies.