Electrohydrodynamics of particle-covered drops

We experimentally investigate the effect of surface-absorbed colloidal particles on the dynamics of a leaky dielectric drop in a uniform DC electric field. Depending on the particle polarizabilty, coverage and the electrical field intensity, particles assemble into various patterns such as an equatorial belt, pole-to-pole chains or a band of dynamic vortices. The particle structuring changes droplet electrohydrodynamics: under the same conditions where a particle-free drop would be a steady oblate spheroid, the belt can give rise to unsteady behaviours such as sustained drop wobbling or tumbling. Moreover, particle chaining can be accompanied by prolate drop deformation and tip-streaming.