Migration of Active Rings in Porous Media

Abstract

Active organisms living inside tight, disordered, porous environments can effectively navigate through their habitat by generating localized forces along their membrane and temporally deforming their shape. To investigate the physical properties that underlie the dynamics of shape-deforming active organisms in the disordered environment, we simulate active ring polymers-structured by connecting Active Brownian Particles by springs of uniform spring constant -in two-dimensional random porous media and record their migratory patterns. The dynamics of different systems of active ring polymers has been simulated: flexible, inextensible, and semiflexible. Deformation of flexible and inextensible ring polymers driven by active forces -in form of expanding and shrinking in the pore space-allow them to navigate smoothly through the disordered micro-environment. In contrast, semiflexible rings undergo transient trapping inside the pore space; the degree of trapping is inversely correlated with the increase in active forces. Migration of active rings in the disordered environment is facilitated by their response to the change in their activity; while flexible rings swell with an increase in activity, inextensible and semiflexible rings monotonically shrink upon increasing the strength of the active force. Together, our findings identify the optimal migration of active ring polymers through porous media. Our work has also direct implications on how shape deforming organisms can navigate through porous environments by generating localized forces along their membrane, and how their membrane stiffness plays a role in their shape deformation.