A new wearable technology developed at Carnegie Mellon University could turn one's entire lower arm into a touchpad.

"SkinTrack," built by the Human-Computer Interaction Institute’s Future Interfaces Group, detects touches at discrete locations on the skin, enabling functionality similar to buttons or slider controls.

Previous “skin to screen” approaches have employed flexible overlays, interactive textiles, and projector/camera combinations. SkinTrack, by contrast, requires only that the user wear a special ring, which propagates a low-energy, high-frequency signal through the skin when the finger touches or nears the skin surface.

“SkinTrack makes it possible to move interactions from the screen onto the arm, providing much larger interface,” said Chris Harrison, assistant professor in the HCII and adviser to the research.

Electrodes are integrated into the watch’s strap. The electrodes corresponding to the 12 o’clock and 6 o’clock positions on the watch detect phase differences that can determine the position of the finger along the width of the arm; electrodes at the 3 o’clock and 9 o’clock positions similarly can determine the finger’s position along the length of the arm.

The researchers determined when the finger was touching the skin with 99 percent accuracy; the team resolved the location of the touches with a mean error of 7.6 millimeters.

A number pad application enabled users to use the back of the hand as a dial pad for the onscreen number pad; hovering a finger over the hand acts as a cursor, highlighting numbers on the screen to aid in targeting touch points.

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