Batteries not required: The Touch Lumen flashlight uses your body heat to generate light

A New York-based engineer has developed a new type of flashlight that does not require an external power source, but instead uses the heat of a person’s body for power. The flashlight has well exceeded its fundraising efforts on crowdfunding site, Kickstarter.

What’s so great about Touch Lumen?

It appears to be an ordinary flashlight with a brightness comparable to the one your smartphone gives off, but it’s coolest feature is that it doesn’t need batteries, making it virtually eternal.

According to project creator, Ross Zhuravskiy, Lumen has relatively simple work principle. Basically, you touch the thermoelectric generator – the small ceramic bar located on the device – and it can produce an electric current when there is a significant discrepancy in temperature.

“In my application difference between temperature of your body (about 98 °F) and environment (at least 82 °F) is enough to generate power for single LED. The metal body of Lumen serves as a radiator,” Zhuravskiy writes on his Kickstarter page.

Touch Lumen can’t exactly power  high-output LEDs just by touching the thermoelectric generator, but when your temperature is 98 °F and the air temperature is 82 °F Lumen can produce about 15 mA@3v. If the temperature difference is greater, excessive power is stored in a capacitor to power Lumen so you can use it whenever you need it. It can store enough energy to power a 5-mm Cree LED with a 3,000 mCd light output.

Zhuravskiy was thinking a few steps ahead when he developed the Touch Lumen. What happens when you’re in the dark and can’t find your flashlight? He suggests purchasing a Lumen with a tritium vial, a glass tube with a phosphor layer  and tritium gas inside. The tiny vial is capable of producing light for over a decade

The Lumen has already raised almost $50,000 of its initial $5,000 funding goal, with 24 days remaining. If you’re interested, you can pre-order one for $35.