Superhydrophobic displays

Lotus leaves are an example of a surface that displays syperhydrophobic characteristics -- a surface that actively repels water. The characteristic itself is not novel, but recently Aalto University researchers have exploited this property to create a new kind of display: one that only uses water and air. In the video below, water is poured onto the lotus-leaf-like surface, flowing away to non-hydrophobic regions. Eventually, water seems to coat the surface, but in reality is resting on a thin film of air that prevents surface-water contact. Next, a high-velocity spray locally increases the pressure of the air layer between the water and the hydrophobic surface, leaving behind a thinner air layer -- with different optical characteristics -- and resulting in a contrast with which researchers can write or draw pictures.