Canadian high school student Ann Makosinski
demonstrating her body-heat powered Hollow
Flashlight
At the tender age of 15, Canadian high school
student Ann Makosinski has designed and built
a flashlight powered by body heat. Her Hollow
Flashlight secured her a finalist slot in the
15-16 age group of the Google Science Fair
ahead of thousands of entries from more than
100 countries. My science project in tenth
grade was a volcano that only worked about
half the time, so I think she has me beat.
The LED flashlight relies on the thermoelectric
effect, with tiles that generate electricity from
the differences in temperature to generate
electricity. The tiles are fixed to the outside of
a hollow tube so that when held, one side of
the tile is heated by the warmth of the hand,
while air flowing through the hollow tube helps
keep the other side cool. The electricity
generated by the temperature differential
between either side of the tile powers the LED
light.
Makosinski built two different flashlights. The
first was made using a tube of aluminum,
which is a good heat sink material thanks to its
high thermal conductivity, while the second
was built using a PVC tube.
Both models work better when the difference
between the ambient temperature and body
temperature is greater, which is to say, when
it's colder. So while the flashlights worked with
an air temperature of 10° C (50° F), they
emitted more light with the air temperature at
5° C (41° F). Still, she claims that both were
able to maintain a steady beam of light for 20
minutes, even in the warmer temperature.
The final cost of each flashlight came to only
just over CA$26 (US$25), but if mass-
produced, the cost would obviously be
substantially lower.
Makosinski and the 14 other Google Science
Fair finalists will travel to Google's Mountain
View, California campus in September where
winners will be announced in each of the three
age groups. One grand prize winner will also
receive a $50,000 scholarship from Google
and a trip to the Galapagos Islands.
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