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Updated: Jun 5, 2026

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
Adhesion of liquid droplets to rough surfaces
Ri Li1, Azar Alizadeh, Wen Shang
1GE Global Research Center, Niskayuna, New York 12309, USA. liri@ge.com
Abstract:
We study the adhesion of liquid droplets to rough surfaces, focusing on how adhesion changes with surface chemistry and roughness. For hydrophobic surfaces (equilibrium contact angle θ(e)>90°), although increasing surface roughness augments apparent contact angle, it does not necessarily always reduce adhesion. In a domain defined by roughness and equilibrium contact angle, this study identifies regions where adhesion increases or decreases with increasing roughness. The two regions do not border at θ(e)=90°. It is found that making surfaces with low roughness ratio (close to 1) does not reduce adhesion unless the surface material is highly hydrophobic (θ(e)>120°). In other words, to reduce adhesion for existing hydrophobic materials (90°<θ(e)<120°), high roughness ratios are needed. Additionally, to reduce adhesion, the geometry of microstructures should be designed such that wetted fraction decreases with increasing roughness ratio. This study is of particular importance for the design of textured superhydrophobic surfaces.
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