Following these three design features, we fabricated a microstructure framework consisting of microscale inverted-pyramidal cavities. Using parameters including the width of the ridge w (the distance between the adjacent holes), the width of the cavity l and the height h (Fig. 2a), the liquid–solid contact fraction (f micro) can be tailored according to the following equation:Inverted-pyramidal microstructures with α ≈ 125° were manufactured on silicon substrates by photolithography (Fig. 2b, Supplementary