Smartwatch screens can feel maddeningly small when trying to navigate apps. But why limit yourself to a 2-inch screen when there's so much prime real estate surrounding it? 

A Carnegie Mellon University research lab this week introduced a solution that turns your arm and hand into an extended touch screen. Dubbed SkinTrack, it enables continuous touch tracking on the skin—in the most fashionable way.

Users wear a "harmless" high-frequency AC-signal-emitting ring, which communicates with electrodes in the watch's wristband, powering interactive applications like swiping, touching, and tracking. It even works when the skin is covered with clothing.

From the minds of the university's Future Interfaces Group, SkinTrack can handle app navigation, selection, scrolling, and confirmation.

Say you're out for a run: Don't stop—panting and out of breath—just to look for your favorite motivational song on your wrist. Keep moving, and use the back of your hand and a right-swipe gesture to open the music player and launch the right tunes.

"As our approach is compact, non-invasive, low-cost, and low-powered, we envision the technology being integrated into future smartwatches, supporting rich tough interactions beyond the confines of the small touch screen," the Future Interfaces Group said in a paper.

Despite testing at 99 percent accuracy, there are a number of obstacles on the way to SkinTrack commercialization. Chief among them is sensing stability over time and the fact that slight changes to the body (hydration, sweat, etc.) can disorient the program. Researchers also cited the issue of powering the signal-emitting ring, as well as figuring out how much pressure is needed for each action.