Wetting transition of water droplets on superhydrophobic patterned surfaces

The relationship between water droplet size and surface geometric parameters governs the transition from composite solid-air-liquid interface to homogeneous solid-liquid interface on superhydrophobic surfaces. This study presents the effect of varying droplet size on the wetting properties of patterned Si surfaces. We propose a criterion that the transition from the Cassie-Baxter regime to the Wenzel regime occurs when the droplet droop is greater than the depth of the cavity. The trends are explained based on experimental data and in terms of the proposed transition criterion. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.