Clever idea to base the action not only upon the number of fingers, but also on the fact whether they’re close or far apart. A prototype of the interface is available for one to play with (visit using a touch capable device)
Capacitive Fingerprinting is a new sensing approach to differentiate between multiple users engaging with touch screens and other interactive surfaces. Although currently touchscreens can differentiate multiple points of contact, they are not able to differentiate who is touching the device. In Capacitive Fingerprinting we consider how the electrical properties of human bodies and their attire can be used to support user differentiation on touchscreens.