Rugged phone cases are bountiful. But, while they may offer some additional thermal protection, they're not built for true extremes. For that, you'd need either piles of insulation (too bulky) or some way to control the temperature inside the case. ThermoShield, one of over a dozen student-run companies vying for attention at Northeastern University's Husky Startup Challenge, went the latter route by slipping a Peltier element inside a slim plastic shell. The current prototype was built on a 3D printer and clearly created for an iPhone, but plans for the initial model should be simple enough to port to any handset. A standard watch battery powers the small plate and by controlling the voltage across it you generate either small amounts of heat or produce a slight cooling effect. A simple switch or slider would be used to manually control the flow of electrons. Trekking through the arctic tundra? Simply crank up the heat to keep your phone from freezing to death. Meandering through the Sahara? Take advantage of the Peltier's thermoelectric cooling properties to keep the Gorilla Glass from melting.
According to one of the creators, Hannah Bialic, it wouldn't be terribly difficult to add automatic temperature control. Though, development costs could significantly drive up the price of the ThermoShield. The hardware could all be baked directly into the case itself or an app could be created that would automate everything. Obviously, though, relying on software would limit the case to working with a single device (and let's be realistic, it won't be your beloved Nexus 4). There's no telling when or if you'll actually be able to pick up one of these variable temperature shells, but you can add your name to the mailing list at the more coverage link.