Versatile low-Reynolds-number swimmer with three-dimensional maneuverability

TL;DR

This paper introduces the Quadroar, a novel low-Reynolds-number swimmer capable of three-dimensional movement and reorientation, achieved through a unique design combining linear actuation and disk rotation, with potential nano-scale applications.

Contribution

The paper presents the design and simulation of the Quadroar, a versatile swimmer with 3D maneuverability, breaking time symmetry through combined disk rotation and linear actuation, enabling complex trajectories.

Findings

Quadroar can swim along arbitrary 3D trajectories.

It exhibits planar and 3D periodic and quasi-periodic orbits.

Feasibility of nano-scale fabrication using photoactive molecular rotors is discussed.

Abstract

We design and simulate the motion of a new swimmer, the {\it Quadroar}, with three dimensional translation and reorientation capabilities in low Reynolds number conditions. The Quadroar is composed of an $\texttt{I}$-shaped frame whose body link is a simple linear actuator, and four disks that can rotate about the axes of flange links. The time symmetry is broken by a combination of disk rotations and the one-dimensional expansion/contraction of the body link. The Quadroar propels on forward and transverse straight lines and performs full three dimensional reorientation maneuvers, which enable it to swim along arbitrary trajectories. We find continuous operation modes that propel the swimmer on planar and three dimensional periodic and quasi-periodic orbits. Precessing quasi-periodic orbits consist of slow lingering phases with cardioid or multiloop turns followed by directional propulsive phases. Quasi-periodic orbits allow the swimmer to access large parts of its neighboring space without using complex control strategies. We also discuss the feasibility of fabricating a nano-scale Quadroar by photoactive molecular rotors.