We're all intimately familiar with the backs of our hands, so why not use them as a haptic interface to control our gadgets? That's the idea behind the device pictured above -- a nifty little wrist sensor that turns your paw into a flesh-toned trackpad. Designed by Kei Nakatsuma, a PhD student at the University of Tokyo, this contraption employs infrared sensors to track a user's finger as it moves across the back of a hand. These movements are mirrored on a wristwatch-like display, thanks to seven IR detectors and a set of piezoelectric sensors, effectively turning any digit into an organic stylus or mouse. Nakatsuma, who unveiled his work at this week's SIGGRAPH, says his creation can't handle the more complicated, pinching or rotating gestures you could manipulate on most smartphone touchscreens and acknowledges that the screen can be difficult to read in direct sunlight. But the underlying technology could pave the way for similarly handy designs, while allowing users to interact with their gadgets without having to constantly glance at their screens, or go fishing in their pockets. Feel your way past the break to see a video of the device in action.