Fifteen-year-old Ann Makosinski had a bright idea for a flashlight that doesn’t need batteries: power it with the heat from the palm of your hand. One year after her piezoelectric flashlight took home the bronze medal in the Canada Wide Science Fair, Ann is returning with her “Hollow Flashlight” that operates using the Seebeck Effect - converting heat directly into electricity.
Image: St. Michaels University School Videos
Noting that the human body radiates about 5.7 mW/cm2 and the palm has about 10 cm2 of usable area, she determined that a 10% efficient Peltier tile could produce more than the 0.5 mW needed to light an LED. The problem was that the Peltier devices only generated 50 mV, not enough to forward bias the LEDs to turn them on. She did a little research and designed a four-component DC-DC converter that stepped the voltage up to 5V.
The temperature differential needed to activate the Peltier tiles was created by attaching the tiles to a hollow aluminum tube and surrounding the tube with a PVC pipe. A cut-out in the PVC pipe allows the hand to touch - and heat - the Peltier tiles, and the air flowing through the tube cools the other side.
In addition to entering her flashlight in the Canada Wide Science Fair, Ann’s design was selected as a finalist in the Google Science Fair, where she could win a $50,000 scholarship and a trip to the Galapagos Islands. Ann, whose first toy was a box of transistors, hasn’t decided on a career just yet, but she’s sure it will be something the the sciences. I hope she considers engineering! She takes inspiration from inventor Nikola Tesla, scientist Marie Curie, and musician/composer Ravi Shankar.
Here’s Ann explaining how the flashlight works:
Video: St. Michaels University School Videos
To me this is more than just a science project or an innovative flashlight design. I think we’ll be seeing an increase in the use of Peltier devices to help turn wasted heat into electricity. I recently read about research involving photovoltaic panels with thermoelectric generators (TEGs) attached to them. The TEGs serve a dual purpose: first, with the solar panel on one side and a heat sink on the other, the TEG helps cool the PV panel. This increases the PV’s efficiency, which is adversely affected by heat. Second, it turns that waste heat into electricity. Double win! At the moment TEGs are only about 10% efficient and somewhat expensive to produce, but these are technical limitations that can be overcome with time and ingenuity. (One researcher is making TEGs with a 3D printer.) Any young PhDs out there looking for a research agenda? I think TEGs are ripe for the picking.