A high school student has invented a LED flashlight that uses body heat to light up.
A little known fact: The human body, at any given moment, produces energy equivalent to a 100 watt light bulb. In that sense, we're always wasting our energy that can be used to, well, power a light bulb. It's this line of thinking that led a 16-year-old to invent the first flashlight powered entirely by body heat. Ann Makosinski's "Hollow Flashlight" isn't the only manually-powered light out there. But whereas other products generate energy with shaking or even hand cranking, her award-winning prototype shines the moment you pick it up.
Makosinski, a high school sophomore at St. Michaels University School in Victoria, British Columbia, initially thought of the idea after learning that a friend in the Philippines, who didn't have electricity, was failing in school because she didn't have enough time to study during daylight hours. Her friend's dilemma is surprisingly common among a growing number of people in developing regions that either can't afford or don't have access to a power grid. For Makosinski, it served as an impetus to apply what she had learned about energy-harvesting materials from experiments she's been conducting since the seventh grade.
Still, Makosinski was unsure whether heat from a person's hand was enough to fuel a flashlight equipped with an LED bulb. To capture and convert energy, she settled on Peltier tiles, which produces electricity when the temperature differential between the two sides is 5 degrees Celsius, a phenomenon known as the Peltier effect. The durable material, which has no moving parts and an indefinite lifespan, was built into the flashlight's casing to simultaneously absorb heat from a person's hand along the outside of the flashlight along with the cool ambient air on the inside of the gadget.