High-Speed Propulsion of Flexible Nanowire Motors: Theory and Experiments

TL;DR

This paper introduces a new design and theoretical model for high-speed, flexible nanowire motors driven magnetically, demonstrating their effective propulsion in biological environments for biomedical applications.

Contribution

It presents a novel experimental design and elastohydrodynamic model for flexible nanowire motors, highlighting the role of flexibility in propulsion efficiency.

Findings

Nanowire motors reach speeds up to ~21 micrometers per second.

Theoretical predictions align well with experimental results.

Nanomotors operate effectively in human serum, showing potential for biomedical use.

Abstract

Micro/nano-scale propulsion has attracted considerable recent attention due to its promise for biomedical applications such as targeted drug delivery. In this paper, we report on a new experimental design and theoretical modelling of high-speed fuel-free magnetically-driven propellers which exploit the flexibility of nanowires for propulsion. These readily prepared nanomotors display both high dimensional propulsion velocities (up to ~ 21 micrometer per second) and dimensionless speeds (in body lengths per revolution) when compared with natural microorganisms and other artificial propellers. Their propulsion characteristics are studied theoretically using an elastohydrodynamic model which takes into account the elasticity of the nanowire and its hydrodynamic interaction with the fluid medium. The critical role of flexibility in this mode of propulsion is illustrated by simple physical arguments, and is quantitatively investigated with the help of an asymptotic analysis for small-amplitude swimming. The theoretical predictions are then compared with experimental measurements and we obtain good agreement. Finally, we demonstrate the operation of these nanomotors in a real biological environment (human serum), emphasizing the robustness of their propulsion performance and their promise for biomedical applications.