Superhydrophobic Tracks for Low-Friction, Guided Transport of Water Droplets

We demonstrate a simple yet efficient approach for droplet transport, in which the droplet is moving on a superhydrophobic surface, using gravity or electrostatic forces as the driving force for droplet transportation and using tracks with vertical walls as gravitational potential barriers to design trajectories. We further demonstrate splitting of a droplet using a superhydrophobic knife, and drop-size selection using superhydrophobic tracks with a local widening.