Control of microstructures propelled via bacterial baths

Elizabeth E. Hunter, Nathaniel Chodosh, Edward B. Steager, Vijay Kumar

Abstract: In this work, we explore a unique approach to harvest energy from active matter in order to independently power and control many untethered, mobile microrobots. More specifically, we investigate microstructure transport caused by stochastic collisions between freely swimming cells and rigid microstructure boundaries in a dense bacterial bath. We characterize the motion of asymmetrically shaped microstructures, specifically gears and chevrons, and demonstrate control of these microrobots by altering the motility of swimming cells with high intensity blue light. We demonstrate both rotational and translational motion control using a custom system for tracking and real-time automated exposure of local bath regions using visual feedback. These experiments are supported by a mathematical model and simulations which describe the dynamics of a microstructure propelled by many stochastic cell structure collisions. This model allows us to predict microrobot trajectories and to develop improved strategies for microrobot design and control.