New tech turns your arm into a smart watch touchpad

Carnegie Mellon researchers may help you to work around that tiny touchpad

skintrack graphic

Carnegie Mellon researchers have developed a technology that turns the skin on the arm into a touchpad.

Credit: Carnegie Mellon University

A lot of people like the idea of a smart watch but don't like having to use a tiny touch screen.

Big fingers and a tiny screen can lead to frustration and errant screen commands.

Researchers at Carnegie Mellon University have developed a wearable technology that enables users to turn the skin on their lower arm into a touchpad, giving them a bigger surface to input information or commands to their smart watch.

Unlike other solutions that have used flexible overlays or a combination of a projector and camera, the researchers' new technology, called SkinTrack, only requires the user to wear a special ring that produces a low-energy, high-frequency signal through the skin when a finger touches or nears the skin surface.

"A major problem with smart watches and other digital jewelry is that their screens are so tiny," said Gierad Laput, a Ph.D student in the university's Human-Computer Interaction Institute and a member of the project's research team. "Not only is the interaction area small, but your finger actually blocks much of the screen when you're using it. Input tends to be pretty basic, confined to a few buttons or some directional swipes."

The researchers said they have used SkinTrack as a game controller, to scroll through lists on smartwatches, to zoom in and out of onscreen maps, and to use a dial pad.

When using this new technology, they also could determine when a finger was touching the skin with 99 percent accuracy . The signals emitting from the ring connect with electrodes integrated into the strap of the smart watch.

"It's possible to pinpoint the source of those electromagnetic waves because the phase of the waves will vary," CMU said in a statement. "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 great thing about SkinTrack is that it's not obtrusive," said Yang Zhang, a CMU Ph.D. candidate, who is also on the research team. "Watches and rings are items that people already wear every day."

Ezra Gottheil, an analyst with Technology Business Research, said this kind of technology could give a boost to the smart watch market.

"I have a hard time typing on even my extra-large iPhone," he told Computerworld. "I just got an Apple Watch and I'm unlikely to do very much with the screen … The more ways there are to control these devices, the more useful they can be."

Gottheil noted that there could be issues with the new technology, such as when the user is wearing long sleeves or the battery life of the ring.

Carnegie Mellon also said the ring's battery is one of the challenges with the technology.

"The system has some limitations," the university said. "Keeping the ring powered up is a challenge. Signals also tend to change as the device is worn for long periods, thanks to factors such as sweat and hydration and the fact that the body is in constant motion."

CMU also reported that researchers believe the technology, including the high-frequency signals emitted by the ring, are not harmful to the user.

"The technology is safe," the university said. "No evidence suggests that the radio frequency signals used by SkinTrack have any health effects. The body is commonly excited by daily appliances -- everything from the tiny amounts of current drawn from the finger by touchscreens to the electromagnetic noise emanating from fluorescent lights -- with no ill effects."

This story, "New tech turns your arm into a smart watch touchpad" was originally published by Computerworld.

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