Smartwatches help users keep track of the time, quickly respond to simple texts, and ignore calls from their moms without pulling out a phone. But there's one unpleasant feature of the smartwatch that's kept them from being ubiquitous—it takes two hands to use one.Yeah, the smartwatch sits on a the wrist but as soon as it pings you need to bring it up to your face and use your free hand to manipulate it. I can scroll through a newsfeed on a smartphone one-handed while cooking pancakes. Smatwatches were supposed to be more accessible than smartphones, but end up requiring both hands in order to do anything useful.Enter WristWhirl, a prototype designed by Darthmouth students Jun Gong and Xing-Dong Yang with the help of University of Manitoba student Pourang Irani. Their visions is simple: build sensors into the watch's wrist strap and let the users wrist do the navigating.The trio attached 12 infrared proximity sensors and a piezo vibration sensor to a plastic wrist strap, then hooked the whole thing up to a 2-inch display running an operating system of their own design. The results are pretty cool.Wearers use 12 different gestures to open and close messanger apps, scroll through music, and even play games such a Tetris and Fruit Ninja … all with the flick of a wrist. According to the team's write up of the watch, their cheap prototype worked 85 percent of the time of human users. Those are great results for a first draft.