Dynamics of active poroelastic filaments in Stokes flow.

Abstract

Active particles are self-propelled microswimmers with potential applications in biomedicine and microfluidics. With recent advances in manufacturing technology, it is now possible to experimentally realize soft and flexible artificial microswimmers, which afford more complex dynamics and offer exciting new routes for trajectory control versus traditional rigid designs. Inspired by landmark work simulating the dynamics of flexible active filaments, we present a simple method to study the dynamics of active poroelastic microbots of general shape. Focusing on filament designs, we predict that sufficiently flexible "Janus pusher" filaments may exhibit oscillating dynamics as they swim forward and that under certain conditions, "Saturn" filaments may perform locomotion on spiral trajectories and exhibit "run-and-tumble" dynamics reminiscent of bacterial motion. Finally, we consider a simple extension of our framework that qualitatively incorporates stimuli-responsive hydrogel behavior, which we demonstrate may be used to steer Janus rods. Our results suggest that flexibility and responsivity may play a key role in expanding the functionality of active particles in intelligent artificial microswimming studies.