LED powered flashlight by the heat of one's hand using aluminiumhttps://www.cbc.ca/news/technology/story/2013/06/27/technology-google-science-fair-finals-ann-makosinski.html
...
Makosinski made two different flashlights, each using a slightly different kind of Peltier tile, by assembling the electronics with other parts:
-
An aluminum tube, obtained from a mechanical shop at the University of Victoria, where her father works as a laboratory manager. The aluminum was used to transfer the cooler temperatures of the air to one side of the Peltier tiles.
-
A PVC tube from Home Depot used to house the aluminum tube, with an opening cut in it to allow a person's hand to come in contact with the other side of the Peltier tiles.
Makosinski tested the flashlights and found that both were brighter when the air temperature was 5 C than when it was 10 C, due to the bigger difference between body temperature and the air temperature. But even at 10 C, both flashlights maintained a steady beam of light for over 20 minutes, she reported.
In all, the materials for each flashlight cost about $26, she said, but she thinks that if it were mass produced, it could be manufactured and sold for a far lower price.