Patterning of particulate films using Faraday waves

Faraday waves were used to create a patterned particulate film on the surface of a glass substrate. The process involves deposition of a thin liquid film on the substrate, where the liquid is comprised of water and a concentrated suspension of particles. Faraday waves were created on the surface of the liquid film by subjecting the substrate and film to a vertical oscillation. Because the films are thin, the standing waves create velocity fluctuations that are not negligible near the substrate surface. As the particles in the liquid settled to the bottom, the flow field caused by the waves caused preferential particle deposition organized in a pattern determined by the Faraday wave field. Subsequent evaporation of the liquid film left a particulate film on the solid substrate that retained the pattern of the original wave field. We refer to these particulate films as Faraday films. The length scale of the patterns in these films was on the order of millimeters in the experiments described here. Use of higher frequency oscillations could permit the formation of Faraday films having smaller spatial scales. (C) 2003 American Institute of Physics.