Tiny drops on tiny texture

Texturing solids is a way to provide original properties towardsl liquids. Then, drops can be made less adhesive and/or less frictional, as observed on water repellent or liquid infused materials. Generally, the scale of the liquid is much larger than that of the texture, so that properties (wetting or friction properties for instance) are averaged over a large collection of « defects ». Cases where the drop scale is comparable with that of the texture were less studied, despite their practical interest. For instance, it was shown that adding macro-texture to micro-texture does shorten the rebound time of droplets. Also, a liquid repelled by a texture will be stuck to it if it is (!) built by condensation, that is, by increasing the drop size from a minute volume to a macroscopic one. We plan to discuss how the use of tiny texture allows us to modify this picture (and give rise to anti-fogging materials), and a few things we learn from the observation of such situations.