Beams, Bots, and Beyond: Elastic Path to Microbot Intelligence

In recent years, self-propelled microbots (Hexbug Nano) have emerged as a tunable and reliable means for developing active solids. The collective behavior of such microbot swarms in confined and crowded environments has received considerable attention. While previous endeavors have sought to harness external stimuli such as lights and magnets to control such swarms in forming clusters or directing movements, these approaches often require intricate design alternations and ancillary hardware. Here, we show a novel mechanism of coupling nonlinear elasticity to guide these brainless agents in forming structured assemblies capable of directed motion and emergent intelligent behaviors. We study two configurations: a runner, where an elastic beam connects a pair of microbots, and a spinner, where three are connected in a triangular geometry. The active force generated by the microbots suffices to induce beam buckling, facilitating a form of "communication" within the assemblies. Leveraging such physical interaction allows modulation of the assemblies' translational and rotational motions. With experiments, numerical simulations, and toy models, we rationalize how such microbot assemblies can exhibit intelligent behaviors such as maze navigation and bacterial run-and-tumble locomotion.