Creating a truly multi-user, multi-touch display is a tricky prospect. How do you know who's who short of turning the screen into one giant fingerprint reader? Chris Harrison, Ivan Poupyrev and Munehiko Sato at Disney Research have suggested in a paper that fingerprinting on a capacitive touchscreen isn't far off -- it's just what we need to fingerprint that matters. Rather than look for physical ridges, the scientists' method sweeps through AC frequencies to
