Flexible helical yarn swimmers

TL;DR

This paper explores a novel flexible yarn swimmer composed of intertwined elastomer fibers, demonstrating helical motion driven by chemical or external excitation, with motion characteristics highly sensitive to geometric and excitation parameters.

Contribution

It introduces a new design of a flexible helical yarn swimmer with active and passive fibers, analyzing its motion response to chemical and external stimuli.

Findings

Swimmer moves along a helical trajectory.

Velocity depends on excited region size and yarn pitch.

External excitation effectiveness varies with beam direction.

Abstract

We investigate the motion of a flexible Stokesean flagellar swimmer realised as a yarn made of two intertwined elastomer fibres, one active, that can reversibly change its length in response to a local excitation causing transition to the nematic state or swelling, and the other one, a passive isotropic elastomer with identical mechanical properties. A propagating chemical wave may provide an excitation mechanism ensuring a constant length of the excited region. Generally, the swimmer moves along a helical trajectory, and the propagation and rotation velocity are very sensitive to the ratio of the excited region to the pitch of the yarn, as well as to the size of a carried load. External excitation by a moving beam is less effective, unless the direction of the beam is adjusted to rotation of the swimmer.