a Sliding measurement results on different ARC designs. The radius of curvature of the ARC pointed downhill or uphill. The critical sliding angle was recorded from the accelerometer when the droplet started to slide off the surface. The center-to-center period widths (P) for groups (a1), (a2), and (a3) were 50, 100, and 200 µm, respectively, and the other parameters were R = 1000 µm, w = 10 µm, and W = 1800 µm. The radii of curvature (R) for groups (b1), (b2), (b3), and (b4) were 1000, 1100, 1500 µm, infinity (straight lines), and other parameters were P = 100 µm, w = 10 µm, and W = 2000 µm. Three droplets were used for each measurement. Data are shown ±one standard deviation for n = 3.