German scientists develop a touchless `touch-screen'

The touchless display, by scientists at the Max Planck Institute for Solid State Research in Stuttgart and the University of Munich, consists of alternating, ultra-thin layers of phosphatoantimonate acid - a crystalline solid at room temperature - and silicon dioxide or titanium dioxide nanoparticles.

When a human finger comes within several millimetres of the display, the humidity from the water molecules emitted from pores in the skin is converted by the so-called photonic crystals into an electrical signal or a colour change within a few milliseconds.

Besides allowing largely smudge-free smartphones, tablets and notebooks, the scientists said, touchless displays would have hygiene benefits for digital devices used in public places, such as cash dispensers and ticket machines.

They didn't say when the displays could be ready for serial production.