The only way to ensure that your phone doesn't die when you need it to most is to carry around a portable charger. But, really, who wants to do that? French start-up Wysips wants to make it so you never have to worry about charging your phone every again.
At the 2011 CTIA Wireless Show, Wysips showed off its new transparent photovoltaic film technology that would cover a mobile phone's screen turning it into a portable solar charger. The thin film (only 0.1mm thin) would provide 250mW of power to "trickle-charge" the battery.
Wysips says that it can scale the film to any size screen. And that it will take a typical phone six hours to fully charge. According to the company, the film would only add a dollar to the cost of each phone.[Laptop Mag via Wired]