Teen builds flashlight powered by body warmth

A Google Science Fair finalist built a hand-warmth-powered flashlight prototype that needs no batteries.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
2 min read
Ann Makosinski and flashlight
Ann Makosinski shows off her Hollow Flashlight. Video screenshot by Amanda Kooser/CNET.

Ann Makosinski is a 15-year-old with a flashlight obsession. She won a bronze award for a piezoelectric flashlight at the Canada-Wide Science Fair last year. This year, her battery-free Hollow Flashlight has taken her all the way to the top-15 finalists of the Google Science Fair.

Makosinski was inspired by the idea that the human body is like a walking 100-watt lightbulb with untapped thermal energy potential. She decided to build a flashlight powered only by the warmth of a hand.

The basis for the Hollow Flashlight is Peltier tiles, tiles that produce electricity when one side is heated and the other side cooled.

Two working prototypes later, Makosinski was able to prove her concept that the warmth of the human hand could power a flashlight. It requires 5 degrees Celsius differential between the surrounding atmosphere and the hand. The flashlight is constructed from a hollow aluminum tube to allow ambient air inside.

The Hollow Flashlight may not be strong enough to blind anyone with science, but it does offer a usable amount of illumination, without cumbersome batteries.

"I made two flashlights that do not use any batteries, toxic chemicals, or kinetic energy. They do not create any noise or vibrations and will always work. The flashlight's only limitation is its need for at least a 5°C temperature difference to provide usable light," Makosinski writes.

There has been much discussion in recent years about the issue of getting young women interested in the sciences. The Hollow Flashlight project should stand as a bright beacon of hope in that regards.