Influence of surface texture size on the apparent equilibrium contact angle of a water droplet. When the texture size is very close to ruh, the surface will be rendered ultrahydrophobic due to the dominance of the line tension effect (intrinsic line dominant region). A textured surface with a high solid fraction can render a surface superhydrophobic when the texture size is on the order of ruh (surface and intrinsic line effects, red solid line, Φs = 0.4). This is in contrast to the Cassie–Baxter theory where superhydrophobic surface cannot be achieved by high solid fraction (i.e., black dotted line, Φs = 0.4). Notice that when r ≫ ruh, the apparent equilibrium contact angle predicted by eq 2 approaches that of the Cassie–Baxter equation (surface effect dominant region). The parameters used for eq 2 are τintrinsic = 5×10−11 J/m, γLV of water = 73 × 10−3 J/m2, and θ = 105°, and p = 0.