Friction Induces Anisotropic Propulsion in Sliding Magnetic Microtriangles

Nano Lett. 2022 Sep 28;22(18):7408-7414. doi: 10.1021/acs.nanolett.2c02295. Epub 2022 Sep 5.

Abstract

In viscous fluids, motile microentities such as bacteria or artificial swimmers often display different transport modes than macroscopic ones. A current challenge in the field aims at using friction asymmetry to steer the motion of microscopic particles. Here we show that lithographically shaped magnetic microtriangles undergo a series of complex transport modes when driven by a precessing magnetic field, including a surfing-like drift close to the bottom plane. In this regime, we exploit the triangle asymmetric shape to obtain a transversal drift which is later used to transport the microtriangle in any direction along the plane. We explain this friction-induced anisotropic sliding with a minimal numerical model capable to reproduce the experimental results. Due to the flexibility offered by soft-lithographic sculpturing, our method to guide anisotropic-shaped magnetic microcomposites can be potentially extended to many other field responsive structures operating in fluid media.

Keywords: Active Colloids; Magnetism; Micromotors; Shape-anisotropy; Soft-lithography.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anisotropy
  • Friction
  • Magnetic Fields*
  • Magnetics*
  • Motion