Locomotion of Active Polymerlike Worms in Porous Media

Abstract

We investigate the locomotion of thin, living \textit{T.~Tubifex} worms, which display active polymerlike behavior, within quasi-2D arrays of pillars with different spatial arrangements and densities. These active worms spread in crowded environments, with a dynamics dependent on both the concentration and arrangement of obstacles. In contrast to passive polymers, our results reveal that in disordered configurations, increasing the pillar density enhances the long-time diffusion of our active polymer-like worms, while we observe the opposite trend in ordered pillar arrays. We found that in disordered media, living worms reptate through available curvilinear tubes, whereas they become trapped within pores of ordered media. Intriguingly, we show that reducing the worm's activity significantly boosts its spread, enabling passive sorting of worms by activity level. Our experimental observations are corroborated through simulations of the tangentially-driven polymer model.