Active polymers translocate faster in confinement

TL;DR

This study combines experiments and simulations to understand how active polymers translocate faster in confined spaces, revealing how confinement and stiffness influence their escape dynamics and providing a physical framework for designing flexible robotic filaments.

Contribution

It introduces a unified physical framework linking confinement, stiffness, and translocation speed in active polymers, supported by biological experiments and simulations.

Findings

Optimal translocation occurs when channel width matches filament diameter.

Flexibility and activity cause reorientation, prolonging escape in wider channels.

A dimensionless ratio predicts transition from axis-aligned to reorientation-controlled motion.

Abstract

Living organisms employ diverse strategies to navigate confined environments. Inspired by translocation observations on California blackworms (\textit{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 blob-like 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.