High School Student Builds Body-Heat Powered Flashlight

Not every design needs scads of high tech materials to make it worthwhile. Sometimes the simple ideas are the best. If you’ve ever needed a flashlight, only to find the batteries haven’t been changed in months or years, you might appreciate the subtle genius of a flashlight powered by your hands alone.

Ann Makosinski, a 15-year-old student at St. Michaels University School in Victoria, Canada has developed just such a flashlight for Google’s Science Fair. She is among 15 finalists selected from entries that span more than 120 countries around the world. The finalists will visit the Google campus in Mountain View, CA, in September for the prize ceremony.

While researching alternative energy sources for her 7^th grade project, Makosinski discovered the existence of Peltier tiles. For those unfamiliar with them, Peltier tiles are essentially heat sinks that produce electricity when heated on one side and cooled on the other. Makosinski did some calculations and figured the tiles could produce enough energy to fuel an LED light, so she purchased some from eBay.

She found the tiles would produce enough energy just from the warmth of human hands to turn on the light, but ran into difficulties producing enough voltage for the apparatus. Eventually Makosinski found a reference to a power converter integrated circuit online that would help boost the energy output, and the flashlight idea came together. From her report:

"I decided to make the flashlight with dimensions of 25mm in diameter and 125mm long. Four of the large Peltier tiles covered 16cm², and four of the smaller tiles had a combined area of 5.4cm².

Tiles were mounted on a milled area of 25mm diameter aluminum tubing, and placed inside a larger PVC pipe, insulated from it by air. The hand gripped the tiles through an opening in the PVC pipe. Air flowing through and around the aluminum tube cooled the flashlight. The circuit was mounted in the front, and the LED was centered in the middle of the tube. The PVC pipe was wrapped with insulating foam. I made two flashlights, the F1 with 4 smaller tiles, and F2, with 4 larger tiles.”

The end result is a flashlight that cost Makosinski around $26 to construct, and has a life of around two hours given a 5° difference between body-heat and ambient temperatures. She says her flashlight idea could be commercialized and each unit built for a small enough investment to bring her flashlight design to homes.

Below you’ll find a short video featuring Makosinski giving an overview of her project.

Sources: CBC, Google Science Fair