Using Your Arm as a Touchpad

Using Your Arm as a Touchpad



Engineers have created a new wearable technology that turns the skin of the forearm into a touchpad. They've dubbed it SkinTrack.

The team at the 
Human-Computer Interaction Institute's Future Interfaces Group at Carnegie Mellon University say that their new system allows for continuous touch tracking on the hands and arms. It also can detect 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 that can be cumbersome. 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.

The great thing about SkinTrack is that it's not obtrusive; and it offers a much larger workspace than the tiny screens of other digital jewellery and smartwatches, the controls of which are often confined to a few buttons or directional swipes.

So how does it work? The user wears a ring that produces a high-frequency electrical signal. When the finger gets near to the skin or touches the skin, that signal propagates through the skin. By using electrodes integrated into the watch's strap, it's possible to pinpoint the source of those electromagnetic waves because the phase of the waves will vary. Electrodes corresponding to the 12 o'clock and 6 o'clock positions on the watch, for instance, can 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 can determine the finger's position along the length of the arm.

The researchers found that they could determine when the finger was touching the skin with 99 percent accuracy and they could resolve the location of the touches with a mean error of 7.6 millimeters. That compares well with other on-body finger-tracking systems and approaches touchscreen-like accuracy.

The researchers showed that SkinTrack could be used as a game controller, to scroll through lists on the smartwatch, to zoom in and out of onscreen maps, and to draw. 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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