Smartwatches still aren't hugely popular. While there have been several reasons put forward as to why this may be the case - lack of functions, poor battery life, no real reason to buy one - many people are put off purchasing the devices because of the difficulty that comes from navigating their tiny displays.

But now, researchers at Carnegie Mellon University's Future Interface Group have unveiled an ingenious solution to the problem: a system that turns the skin on your forearm and hand into a smartwatch touchscreen.

With SkinTrack, users wear a sensing band that sits under the smartwatch and a ring that emits a continuous high-frequency AC signal. Thanks to the four electrodes on the wristband, it's able to measure the distance between the watch and the ring to triangulate the position of a finger and track it in real time.

The system works with up to 99 percent accuracy, and can even be used with a sleeve rolled down. It's able to register when a finger is hovering above the skin and can detect taps, which means you can use the back of your hand to dial a phone number.

"As our approach is compact, non-invasive, low-cost and low-powered, we envision the technology being integrated into future smartwatches, supporting rich touch interactions beyond the confines of the small touchscreen," wrote the creators.

The smartwatch prototype that the team created as a proof of concept demonstrates how the system lets users swipe through their apps, makes selections, scroll through lists, recognize gestures, and even play Angry Birds. But one of the most impressive elements is the way that users can 'drop' apps onto their skin, creating a forearm shortcut they can use later.

The researchers say that the biggest challenge they face before the system moves out of the prototype stage is keeping the ring powered up. They also have to figure out how to account for sweat and body motion, which can affect the signal.

It may be a long way from a commercial product, but SkinTrack could eventually become the best way to operate a smartwatch.