Tiny robots move 45,000 times heavier objects using liquid currents

Researchers from the Max Planck Institute for Intelligent Systems, the University of Michigan, and Cornell University have developed swarms of magnetic microrobots, each about 300 micrometers wide, capable of manipulating objects many times their own weight without physical contact. These microrobots spin under an external magnetic field, generating miniature whirlpools in the surrounding liquid. When operating collectively, their fluid currents combine to create fluidic torque, a hydrodynamic force that can rotate gears, assemble structures, and transport materials with high precision. This contactless manipulation allows the robots to handle delicate objects several millimeters in size by adjusting parameters such as robot number, spin rate, and arrangement. In one notable experiment, the microrobot swarm rotated an object weighing over 45,000 times the mass of a single robot, demonstrating the significant force generated through fluidic interactions. Beyond mechanical tasks, the swarms exhibit adaptive behaviors, switching between rotating and crawling motions to autonomously reorganize based on the