Separation and alignment of chiral active particles in a rotational magnetic field

Abstract

We propose a method for the chiral separation and alignment of active paramagnetic particles in a two-dimensional square box with periodic boundary conditions. In a rotational magnetic field, the dynamic behavior of magnetized particles is strongly determined by the competition between the magnetic interaction and differing chirality. By suitably tailoring the parameters, active particles with different chirality can be aggregated into different clusters and separated. However, when either the magnetic interaction or chirality difference is dominant, the particles are prone to mixing. In addition, the external rotational magnetic field plays a decisive role in aligning particles. The numerical results show that there exists an optimal strength and rotation frequency of the magnetic field, as well as a rotational diffusion coefficient, self-propulsion velocity, and packing fraction, at which the separation coefficient takes its maximal value. The proposed method can be exploited to separate naturally occurring chiral active particles.