Touchscreens are going hands-free with a new device that allows users to scroll through smartphones using only their tongues.MouthPad^, a retainer-like trackpad chip that sits on the roof of the mouth, made its debut at the Consumer Electronics Show this week. It can sense tongue movements, allowing users to scroll, type, make calls and even play chess with a swipe or a click of their tongue.“It is a mouse for your mouth,” Corbin Halliwill, a software engineer at Augmental, the company that crea...