Acoustically driven planar microfluidics

Surface acoustic waves are used to actuate and process smallest possible amounts of fluids on the planar surface of a piezoelectric chip. Chemical modification of the chip surface is employed to create virtual wells and tubes to confine the liquids. Lithographically modulated wetting properties of the surface define a fluidic network, in analogy to the wiring of an electronic circuit. Acoustic radiation pressure exerted by the surface wave leads to internal streaming in the fluid and eventually to an actuation of small droplets along predetermined trajectories. (C) 2004 Elsevier Ltd. All rights reserved.