SkinTrack Turns Your Arm Into a Smartwatch Touchpad

Called "SkinTrack" and developed by the Human-Computer Interaction Institute's Future Interfaces Group, the 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.

"The great thing about SkinTrack is that it's not obtrusive like smartwatches that people wear every day," said Yang Zhang, PhD student in HCII.

Previous "skin to screen" approaches have employed flexible overlays, interactive textiles and projector or 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.

A major problem with smartwatches and other digital jewelry is that their screens are so tiny. "Not only is the interaction area small but your finger actually blocks much of the screen when you're using it," added Gierad Laput from HCII and part of the research team.

"SkinTrack" makes it possible to move interactions from the screen onto the arm, providing much larger interface.

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.

The researchers found that they could determine when the finger was touching the skin with 99 percent accuracy and 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" can 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.

The technology is safe. No evidence suggests that the radio frequency signals used by "SkinTrack" have any health effects, the authors noted.

The team is scheduled to present the technology at the "Association for Computing Machinery's Conference on Human Factors in Computing" in San Jose, California om May 10.