Teen Inventor’s Battery-Free Flashlight Runs on Hand’s Heat

by Kids Discover


In 2013, at age 15, Canada’s Ann Makosinski invented an LED flashlight that needs no batteries — it runs on heat from the hand that’s holding it!

“The Hollow Flashlight,” as Makosinki calls it, taps the body’s thermal energy using Peltier tiles, which produce electricity when you heat one side and cool the other. She made it using aluminum tubing, PVC pipe, foam insulation, and the Peltier tiles.

To power the tiles, the hand holding the flashlight must be at least five degrees Celsius warmer than the ambient air, which flows into the hollow tube and cools the underside of the tiles. The power produced by the average hand yields 5.4 mW at five foot candles of brightness (that’s the light of five candles as seen from a distance of one foot).

She entered her invention in the 2013 Google Science Fair. As one of 15 finalists, Ann became the only Canadian to fly to the tech giant’s Mountain View, CA, headquarters to present work for that fair.

The Victoria, BC, teen was inspired by the fact that the human body generates so much heat. Ann says, “We’re like 100-watt walking light bulbs.” She did tons of web research, and you can read a detailed record of her work in her presentation on the
Google Science Fair site

Even more amazing: She submitted her project just under the wire — a mere 45 minutes before the Google deadline. Makosinski blamed homework and time she had already committed to a project for a local science fair. She’s kind of a science fair vet: In 2012, when she was just a ninth-grader, Makosinski won awards at a Canadian science fair with her Piezoelectric Flashlight, a slightly dimmer but equally green invention.

Her work could spark new ideas for clean energy. As she put it in her Google presentation, this technology could be used to heat schoolrooms, recharge cell phones, and even power wireless medical sensors.

Can we say … her future looks bright?


Kids Discover For over 25 years, we’ve been creating beautifully crafted nonfiction products for kids. With a specialty in science and social studies, our team of talented writers, award-winning designers and illustrators, and subject-experts from leading institutions is committed to a single mission: to get children excited about reading and learning.