Permanent magnetic droplet–derived microrobots
Yuanxiong Cao, Ruoxiao Xie, Philipp W. A. Schönhöfer, Ross Burdis, Richard Wang, Rujie Sun, Kai Xie, Jiawen Zou, Xin Song, Qiao You Lau, Junliang Lin, Jang Ah Kim, Dimitar Georgiev, Jiyuan Tang, Ho-Cheung Ng, Olga Bibikova, Yuyang Zuo, Xiangrong L. Lu, Sharon C. Glotzer, Molly M. Stevens
Abstract
Microrobots hold substantial potential for precision medicine. However, challenges remain in balancing multifunctional cargo loading with efficient locomotion and in predicting behavior in complex biological environments. Here, we present permanent magnetic droplet-derived microrobots (PMDMs) with superior cargo loading capacity and dynamic locomotion capabilities. Produced rapidly via cascade tubing microfluidics, PMDMs can self-assemble, disassemble, and reassemble into chains that autonomously switch among four locomotion modes-walking, crawling, swinging, and lateral movement. Their reconfigurable design allows navigation through complex and constrained biomimetic environments, including obstacle negotiation and stair climbing with record speed at the submillimeter scale. We also developed a molecular dynamics-based computational platform that predicts PMDM assembly and motion. PMDMs demonstrated precise, programmable cargo delivery (e.g., drugs and cells) with postdelivery retrieval. These results establish a physical and in silico foundation for future microrobot design and represent a key step toward clinical translation.