by Chris Bodenner
Called Skinput, the system is a marriage of two technologies: the ability to detect the ultralow-frequency sound produced by tapping the skin with a finger, and the microchip-sized "pico" projectors now found in some cellphones. The system beams a keyboard or menu onto the user's forearm and hand from a projector housed in an armband. An acoustic detector, also in the armband, then calculates which part of the display you want to activate.
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