The Invisible iPhone

Over time, using your smart phone touch screen becomes second nature, to the point where you can even do some tasks without looking. Researchers in Germany are now working on a system that would let you perform such actions without even holding the phone instead you'd tap your palm, and the movements would be interpreted by an "imaginary phone" system that would relay the request to your actual phone.
The concept relies on a depth-sensitive camera to pick up the tapping and sliding interactions on a palm,  software to analyze the video, and a wireless radio to send the instructions back to the iPhone. Patrick Baudisch, professor of computer science at the Hasso Plattner Institute in Potsdam, Germany, says the imaginary phone prototype "serves as a shortcut that frees users from the necessity to retrieve the actual physical device."
Baudisch and his team envision someone doing dishes when his smart phone rings. Instead of quickly drying his hands and fumbling to answer, the imaginary phone lets him simply slide a finger across his palm to answer it remotely.
The imaginary phone project, developed by Baudisch and his team, which includes Hasso Plattner Institute students Sean Gustafson and Christian Holz, is reminiscent of a gesture-based interface called SixthSense developed by Pattie Maes and Pranav Mistry of MIT, but it differs in a couple of significant ways. First, there are no new gestures to learn—the invisible phone concept simply transfers the iPhone screen onto a hand. Second, there's no feedback, unlike SixthSense, which uses a projector to provide an interface on any surface. Lack of visual feedback limits the imaginary phone, but it isn't intended to completely replace the device, just to make certain interactions more convenient.