Vortex-Induced Cargo Transportation by Programmable Collective Behavior of Polymer Nanocomposite Robots

Cooperation of multiple robots is essential to enhance actuation efficiency for time-consuming missions and complete complicated tasks that are unable from a single robot. Herein, we present agile (~180 body lengths per second) and collective above-water swimming of multiple polymer nanocomposite robots, which can transport thousands of microplastics via the water vortex control. To achieve agile above-water swimmability and resultant vortex generation, a musculoskeletal system-mimetic design is adopted to prepare stiff yet lightweight hierarchical nanocomposite robots. By simply varying magnetic frequencies of a pulsed electromagnetic field, swimming modes of the nanocomposite robots are selectively programmed on-demand between rectilinear translational swimming and rotational swimming, allowing the robots to block, deliver, confine, or release thousands of floating microbeads in a divided space rapidly and simultaneously. Moreover, through the collective behavior, the multiple nanocomposite robots generate vortex and demonstrate a collection of > 4,000 floating microplastics in an open space. We further discuss the vortex-induced transportation capability of semi-submerged and underwater millimeter-scale cargos with rolling resistance or sliding resistance.