Scattering of Metal Colloids by a Circular Post under Electric Fields

We consider the scattering of metal colloids in aqueous solutions by an insulating circular post under the action of an AC electric field. We analyze the effects on the particle of several forces of electrical origin: the repulsion between the induced dipole of the particle and its image dipole in the post, the hydrodynamic interaction with the post due to the induced-charge electroosmotic (ICEO) flow around the particle, and the dielectrophoresis arising from the distortion of the applied electric field around the post. The relative influence of these forces is discussed as a function of frequency of the AC field, particle size and distance to the post. We perform numerical simulations of the scattering of the metal colloid by the insulating circular post flowing in a microchannel and subjected to alternating current electric fields. Our simulation results show that the maximum particle deviation is found for an applied electric field parallel to the flow direction. The deviation is also greater at low electric field frequencies, corresponding to the regime in which the ICEO's interaction with the post is predominant over other mechanisms.

Automated summary

In this study, we investigate the scattering of metal colloids by an insulating circular post under the influence of an alternating current (AC) electric field. We analyze the effects of electrical forces such as induced dipole-repulsion, induced-charge electroosmotic (ICEO) flow, and dielectrophoresis on the particles. The relative influence of these forces is examined in relation to the frequency of the AC field, particle size, and distance to the post. Numerical simulations are performed to model the scattering of metal colloids in a microchannel with an insulating circular post under alternating current electric fields. The simulation results show that the maximum particle deviation occurs when the applied electric field is parallel to the flow direction, and this deviation is more significant at low electric field frequencies where the ICEO interaction dominates over other mechanisms.