From moving cargo to climbing walls: Microrobotic behavior of self-propelled flexicles in complex environments

Macroscopic robotics has become an integral part of our daily lives, and it is unsurprising that researchers have focused significant effort on developing smart nanoparticles to initiate a similar revolution on the microscale. In this study, we employ molecular dynamics simulations to explore the robotic capabilities of "flexicles"—a computational model of a three-dimensional, self-driven, deformable cell-like object composed of self-propelled particles confined within a flexible vesicle. By placing flexicles in various environments and scenarios, we demonstrate their ability to autonomously perform complex tasks such as curvature-dependent geometrical trapping, navigating topographical obstacles, and transporting passive cargo particles. We identify a physical mechanism underpinning these behaviors, linking the interactions between flexicles and curved surfaces to deformations that influence the arrangement and ordering of internal active colloids. Our results establish flexicles as promising candidates for dynamic, active, cell-like microrobots and provide a foundation for developing physics-based strategies for other autonomous robotic behaviors in the future.