Dual touch screen
Most mobile devices use some sort of stylus to interact with the touch screen as it is simpler to implement and more accurate. “Big“ fingers cover small objects so they are hard to see and difficult to select. The LucidTouch prototype overcomes these limitations by letting the user touch the back of the device. Touching an object from behind the screen is difficult so the LucidTouch system lets you "see" your fingers through the screen:
The key to making this usable is what we call pseudo-transparency: by overlaying an image of the user’s hands onto the screen, we create the illusion of the mobile device itself being semitransparent. This pseudo-transparency allows users to accurately acquire targets while not occluding the screen with their fingers and hand. LucidTouch also supports multi-touch input, allowing users to operate the device simultaneously with all 10 fingers.
The demo can hardly be called mobile as it uses a web cam behind the device to see where the fingers are. But the idea is pretty cool and the video shows how some of the new ways a user can interact with a “transparent“ touch screen.