By attaching a microphone to a touchscreen, the CMU scientists showed they can tell the difference between the tap of a fingertip, the pad of the finger, a fingernail and a knuckle. This technology, called TapSense, enables richer touchscreen interactions. While typing on a virtual keyboard, for instance, users might capitalize letters simply by tapping with a fingernail instead of a finger tip, or might switch to numerals by using the pad of a finger, rather toggling to a different set of keys.
Another possible use would be a painting app that uses a variety of tapping modes and finger motions to control a pallet of colors, or switch between drawing and erasing without having to press buttons.
Source: physorg.comAdded: 20 October 2011