To make this magic happen, the researchers are using a heat-activated gel that's transparent and fluid at room temperature, but hardens into an opaque, defined shape when warmed. The team's "GelTouch" 7-inch prototype is fronted by a layer of this gel, with another layer of conductive film behind that. The film carries electrical current (and therefore heat) to discrete areas of the display, creating a variety of button layouts -- proof-of-concept patterns include a rectangular key arrangement, a slider (albeit made from a row of the same keys), and a joystick-like nub. (You can check out a video of the team's work here.)
The GelTouch prototype isn't exactly polished, but the researchers imagine the technology being used not only to bring tactile feedback to flat displays, but also where "feeling" your way around a touchscreen would be beneficial -- on a car's infotainment system, for example, so you can keep your eyes on the road. There are plenty of issues that still need to be overcome, however. For starters, the gel requires constant power to stay "activated," and there's a lag period of a few seconds between soft and hard states. Also, the gel isn't transparent when it takes on a distinct form, so you might have trouble typing on a keyboard, for instance, when you can't see the letters behind white blobs of the hardened material. Still, it's certainly an interesting concept, and who knows? One day we mightn't need to choose between the clean face of an all-touchscreen smartphone, and the typing prowess of a BlackBerry.