Emergent Microrobotic Behavior of Active Flexicles in Complex Environments

Abstract

Collections of simple, self-propelled colloidal particles exhibit complex, emergent dynamical behavior, with promising applications in microrobotics. When confined within a deformable vesicle, self-propelled rods cluster and align, propelling the vesicle and inducing changes in the vesicle shape. We explore potential microrobotic capabilities of such vesicle-encapsulated particles, which form a composite particle system termed a `flexicle'. Using molecular dynamics simulations, we demonstrate that the alignment of rods enables flexicles to locomote and respond adaptively to their physical environment. When encountering solid boundaries or obstacles, the rods reorient at the interface, triggering novel emergent behaviors such as crawling, corner-preferencing, wall climbing, and object-latching. These interactions and accompanying internal rod re-arrangement lead to spontaneous, temporary differentiation of the rods into `latchers' and `navigators'. This division of labor among the rods enables coordinated locomotion and environmental response. Our findings establish flexicles as a versatile platform for programmable, geometry-sensitive microrobotic behavior, offering a step toward autonomous colloidal robotics.