Orientation-dependent induced-charge electrophoresis of magnetic metal-coated Janus particles with different coating thicknesses

Abstract

Orientation-dependent induced-charge electrophoresis (ICEP) behaviors are measured in magnetic metal-coated Janus particles, where the orientation of the particle with respect to the electric field is controlled by an external magnetic field. For a thin metallic coating (10 nm), the particle mainly moves normal to the electric field without the magnetic field. The velocities of ICEP in different directions are measured under the magnetic field and clear orientation-dependent velocities are observed. However, for a thick metallic coating (70 nm), the particle mainly moves parallel to the electric field without the magnetic field and shows an opposite tendency for orientation-dependent velocities compared with the thin metallic coated particles. We propose that the strength of the induced dipole of a Janus particle depends on the thickness of the metallic coating, which results in different orientation-dependent velocities of the Janus particle under electric fields.