Enhanced Mobility of Active Polymers in Confined Channels

The translocation of flexible filaments through confined channels is a fundamental process observed in both equilibrium and non-equilibrium conditions. Flexible living organisms, such as semi-aquatic worms like Lumbriculus variegatus (California blackworms), employ a variety of strategies to navigate through highly constrained environments, including tight spaces in wet granular soil or conspecific tangles. Motivated by these natural behaviours, we experimentally investigate the movement of a single worm through an open capillary tube, quantifying its dynamics, including speed and escape time. To further understand the mechanisms driving these movements, we develop a computational model where the worm is represented as a self-propelling active polymer confined within a cylindrical channel. Through simulations, we examine the escape dynamics as a function of confinement radius, channel length, and polymer stiffness. Our findings demonstrate that flexible filaments exhibit faster escape in stronger confinements. Our study provides a foundation for developing bio-inspired robotic systems capable of efficient navigation in complex, confined spaces.