One Per Cent: Programmable friction makes touchscreens sticky

One Per Cent: Programmable friction makes touchscreens sticky: The friction adjustment is actually something of a trick. The surface of the screen itself is made of glass and does not become rougher or smoother. Instead, the glass is made to vibrate at around 26,000 Hz by a series of small mechanical discs that sit at the edge of the screen. This creates a thin film of moving air on top of the glass, which has the effect of making the screen feel slippier. By adjusting the vibrations in response to finger movements across the glass, the system can create a convincing illusion in which objects appear to bump into each other or stick to things.