Superhydrophobic engineering surfaces with tunable air-trapping ability

A versatile hybrid processing method that combines electrostatic deposition of microparticles and subsequent anisotropic plasma etching is described that can generate superhydrophobic engineering surfaces with tunable bimodal roughness and a thin hydrophobic fluorocarbon film. These surfaces exhibit contact angles with water of more than 160° for particle coverage beyond a threshold value. A geometric model based on air-trapping ability is developed to explain this observed threshold value of particle coverage and extended to arbitrary rough surfaces utilizing statistical roughness parameters.