Figure 3.

Magnetic field driven movability of water droplets with different sizes on the superhydrophobic MMA surface. a) The movability of water droplets with different sizes on the superhydrophobic MMA surface (H = 3.5 mm, l = 0.7 mm, and B = 11 mT). The scale bars represent 3.5 mm. b) When the diameter of the droplet was at least 3l, i.e., D ≥ 3l, the water droplets can be transported on the superhydrophobic MMA surface by the moving magnetic field. c) The height of the water droplet on the superhydrophobic MMA surface changes as the diameter of the droplet increases. When the volume of the droplet reaches a certain value, the droplet remains almost constant in height (h _droplet = 4.0 mm) on the superhydrophobic MMA surface. d) Illustration of the effect of the water droplet sizes on its shape and motion characteristics. When the droplet volume is gradually increased, the droplet gradually changes from the pinned state to the drivable state, but the droplet height does not change.