Magnetic confinement of Brownian rotation to a single axis and application to Janus and cluster microparticles

Abstract

We present an experimental, one-dimensional, Brownian rotation system in which the free rotation is confined to a single axis. Control of the rotational diffusion of a single microparticle, or particle aggregate, around a chosen axis, was performed by using a static 1.0 mT external magnetic field. The confined object rotated freely around the chosen axis, and that axis was confined to within 3.9°. This method presents several advantages and may have wide applicability in biological and physical systems of interest.