Five years ago, Patrick Baudisch found that it was getting harder to dial the minuscule buttons on ever-smaller cell phones; he couldn't see what he was tapping on the keypad while he was holding the phone. What he really needed, he decided, was fingers he could see through. So Baudisch, a scientist at Microsoft Research who was studying human-computer interaction, started working on something more practical: LucidTouch, a digital technology meant to give handheld devices the illusion of transparency. An unusual joint venture formalized in 2006 between Microsoft and Mitsubishi Electric Research Labs, LucidTouch is designed to allow the use of all 10 fingers, unlike the BlackBerry or Treo. It has two touchscreens: one in front of the device, for thumbs, and the other in back, where the fingers (which appear onscreen as digital facsimiles) hold the device and type. The inventors envision creating sensors for the back to do the same job as the camera that’s on their prototype. Another goal: multipoint selection, which lets users pinch, zoom, and drag onscreen icons using several fingers, unlike traditional touchscreens, which respond only to single pokes in particular spots. (Even Apple’s iPhone limits users to two-finger touching.) Industry observers expect LucidTouch to be ready for cell phones, gaming devices, and wristwatches within five years, although some participants in an early focus group found its nontraditional keyboard awkward. "The backs of devices are underused real estate," says Scott Klemmer, a Stanford University computer-science professor. "We're not doing anything with them right now."