It is often assumed that touch-screens make handheld devices smaller, as these do away with the need for buttons. But paradoxically, they are often larger than the pushbutton gadgets they replace, according to Patrick Baudisch at the Hasso Plat¬tner Institute in Potsdam, Germany, and Microsoft Research in Redmond, Washington. It is hard to hit small touch targets on a screen because your finger hides what you are aiming for.
Baudisch and his student Gerry Chu at the University of Toronto have developed a fix to that. Called NanoTouch, it has a 6cm screen and a touch pad of the same size on the back. It can detect the touch or press of a finger, allowing you to move a tiny cursor around and click and drag with i When you touch the interface on the back, an image of a finger appears behind the icons on the screen and moves around in sync with your finger, almost as if the device were transparent.
A small active spot marked on the finger's end is used to interact with buttons onscreen. User tests showed that targets just 1.8 mm across we easy to hit using NanoTouch. Targets on conventional touch-screen devices such as the iPhone are at least twice that size.