Finger-tracking tech turns your arm into a touchpad

SkinTrack being used to play Angry Birds(Credit: Carnegie Mellon University)

Smartwatches may be handy, but their tiny touchscreens can easily be obscured by your fingers as you're using them on the device. As a result, we've seen various attempts to move the control surface off of the screen. One of the latest, Carnegie Mellon University's SkinTrack system, moves it onto your hand and lower arm.

Here's how it works …

The smartwatch is mounted on a strap that incorporates multiple electrodes. On the other arm, on your "control finger" (the one that'll be doing the tapping and swiping), you wear a ring that emits a harmless high-frequency electrical signal. As that finger (and ring) approaches and/or touches the watch-wearing arm, that electrical signal is propagated through the skin – even if the skin is covered with clothing.

By comparing the phases of the electrical waves as they're detected by each of the electrodes, it's possible to pinpoint the location of the finger relative to the smartwatch. The system is 99 percent accurate and can locate touches with a mean error of 7.6 mm, which is reportedly in the same ballpark as regular touchscreens.

In lab tests, SkinTrack was successfully used to control a game, scroll through lists, zoom in and out of maps, draw pictures, and operate an onscreen number pad. Hovering the finger over the back of the hand allowed users to move the cursor around on the watch's screen.

Before it can be commercialized, however, the technology still has a couple of kinks to be worked out. For one thing, the prototype ring goes through batteries pretty quickly. Additionally, thanks to factors such as sweat and body motion, the electrical signals tend to change after the ring has been worn for long periods of time.

The system is demo'd in the video below.

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