Quick, large-area assembly of a single-crystal monolayer of spherical particles by unidirectional rubbing.

Rubbing a dry powder of particles in one direction between two rubbery substrates is found to be a quick and highly reproducible, yet inexpensive fabrication technique for assembling particle monolayers with perfect spatial registry on flat or curved surfaces. The optimum rubbing conditions - pressure and speed - for a single-crystal monolayer are shown to depend on particle size. Potential applications are in biosensors, photovoltaics, and light manipulators.