Low wettability gives superhydrophobic surfaces numerous applications, such as self-cleaning, anti-corrosion and anti-icing. In this work, we analyzed the usage of superhydrophobic surfaces in droplet size separation. We developed a theoretical model for predicting the size of a droplet passing through a hole in a thin foil. We compared the results with experimentally determined droplet sizes passing through laser cut holes in a thin copper foil with laser textured and hydrophobized surfaces, which displayed superhydrophobic characteristics. For holes with diameters of 1.2 to 2.0 mm, at which the size of the droplets passing through the hole is lesser than the capillary length of the fluid, the deviation of the theoretically predicted size of the droplet from the measured size is less than 20 %. By reducing the size of the hole the accuracy of the theoretical model increases, as the deviation is less than 10 % for holes with diameters smaller than 1.5 mm. We presented the methodology for dynamic droplet size separation using copper meshes with superhydrophobic surfaces, which were prepared by etching and coating with hydrophobic substances. The droplet size separation depends on the limiting size of the droplets, at which the droplets can still pass through the openings of the mesh. We experimentally determined the limiting size of the droplets for a mesh with 2.46 mm openings, which is located between 4.2 and 4.5 mm.
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