Active Polymers Translocate Faster in Confinement.

Living organisms employ diverse strategies to navigate confined environments. Inspired by translocation observations on California blackworms (Lumbriculus variegatus), we combine biological experiments and active-polymer simulations to examine how confinement and stiffness govern translocation. Active filaments translocate fastest when the channel width is comparable to their diameter, with escape time determined by propulsion speed, filament length, and channel geometry. In wider channels, activity and flexibility induce reorientation-dominated conformational changes that prolong escape. A single dimensionless ratio linking confinement to stiffness captures the transition from axis-aligned escape with short wall deflections for stiffer filaments to reorientation-controlled motion with bloblike shapes for flexible filaments. These results provide a unified physical framework for active translocation in confinement and suggest design principles for flexible robotic filaments in complex environments.