Technique allows use of water and air to create visual displays

Researchers in Cambridge have helped develop a way that water and air can be used to store information and even create visual displays.

The technique uses the very water-repellent (or superhydrophobic) properties of a material with a microscopic structure inspired by a lotus leaf that traps a thin layer of air between the surface of the material and any water touching it.

The surface structure is fabricated so that the air can be trapped in two different ways, and these two states can be used to store information in a similar way to computer binary systems where data is stored electronically as 1s and 0s.

The researchers created a special nozzle to change the pressure on the surface and so alter the way the air is trapped, moving it between tiny microposts grown on the material and even smaller nanofilaments grown on the posts.

‘The minimal energy needed to switch between the states means the system is bistable, which is the essential property of memory devices, for example,’ said Dr Robin Ras of Aalto University, Finland, who led the research alongside a team from Cambridge University and Nokia Research Center Cambridge.

Because there is a visual difference between the two states, the technology can also be used to produce images by moving the nozzle across the surface and drawing with pixel-like preciseness.

The material itself remains unchanged by the process and the ‘screen’ can be wiped simply by removing it from the water.