Dielectrophoretic (DEP) assembly of colloids presents an efficient method to produce colloidal crystals. The properties and the structure of the assembly depend strongly on the properties of the colloids. The earlier DEP assembly of “Janus” particles, having dielectric and conductive halves, has shown a new type of metallodielectric colloidal crystal that is formed where the metal-coated halves of neighboring particles align into conductive lanes through the crystal. Here, we explore “patchy” particles, with less than 50% conductive surface area, which present a novel class of colloids for DEP assembly. These particles are produced by partially modifying the surface of micrometer-sized polystyrene particles using the glancing angle deposition technique.¹ The geometry of the patch is controlled by the angle of incident vapor rays as well as the orientation of the particles within the monolayer. The dielectrophoretic assembly of 50%, 25%, and 10% gold-coated polystyrene particles is studied. We report the crystal structures obtained by DEP assembly of patchy particles. The patchy particles are found to assemble such that the conductive gold patches are in contact with each other, leading to different crystal assemblies for 50%, 25% and 10% coated patchy particles.

1. Pawar A. B.; Kretzschmar I. “Patchy particles by glancing angle deposition”; Langmuir 2008, 24, 355 – 358.