smart

Think about that for a moment: a flashlight that shines for as long as you hold onto it. No more scrambling for and chucking away AA batteries. It could have an immediate impact on more than 1.2 billion people -- one-fifth of the world's population -- who, according to the World Bank, lack regular access to electricity.

Stunningly, no one on record has thought to use thermoelectric technology to power a flashlight. But for Ann, peltier tiles, which produce an electrical current when opposite sides are heated and cooled at the same time, were a convenient solution to a friend's study problem.