Self-Assembly and Manipulation of Particles on Drop Surfaces

It was recently shown by us that particles distributed on the surface of a drop can be concentrated at the poles or equator of the drop by subjecting it to a uniform ac electric field. The dielectrophoretic and hydrodynamic forces which cause the motion of particles depend on the parameters such as the particles’ and drop’s radii, the dielectric properties of the fluids and particles, and the frequency of the electric field. The hydrodynamic force, which arises because of the induced motion in the liquids, is the main focus of this paper. We show that it can be used to control the distribution of particle monolayers on the surface of a drop.