Guiding microscale swimmers using teardrop-shaped posts
Abstract
The swimming direction of biological or artificial microscale swimmers tends to be randomised over long time-scales by thermal fluctuations. Bacteria use various strategies to bias swimming behaviour and achieve directed motion against a flow, maintain alignment with gravity or travel up a chemical gradient. Herein, we explore a purely geometric means of biasing the motion of artificial nanorod swimmers. These artificial swimmers are bimetallic rods, powered by a chemical fuel, which swim on a substrate printed with teardrop-shaped posts. The artificial swimmers are hydrodynamically attracted to the posts, swimming alongside the post perimeter for long times before leaving. The rods experience a higher rate of departure from the higher curvature end of the teardrop shape, thereby introducing a bias into their motion. This bias increases with swimming speed and can be translated into a macroscopic directional motion over long times by using arrays of teardrop-shaped posts aligned along a single direction. This method provides a protocol for concentrating swimmers, sorting swimmers according to different speeds, and could enable artificial swimmers to transport cargo to desired locations.
Cite
@article{arxiv.1701.08410,
title = {Guiding microscale swimmers using teardrop-shaped posts},
author = {Megan S. Davies Wykes and Xiao Zhong and Jiajun Tong and Takuji Adachi and Yanpeng Liu and Leif Ristroph and Michael D. Ward and Michael J. Shelley and Jun Zhang},
journal= {arXiv preprint arXiv:1701.08410},
year = {2017}
}