No this isn’t just another hand-cranked light. The claim is that it generates electricity to power its LED from body heat. Just put a finger or thumb on the fingerprint spot, & the heat from your body will power the light.
http://the-gadgeteer.com/2015/11/23/you-only-need-to-touch-this-flashlight-to-power-it/#more-189658
Kickstarter page:
https://www.kickstarter.com/projects/940015402/lumen-eternal-flashlight-that-doesnt-need-batterie/description
A couple of things to note:
● This light depends on heat energy flow from your body through the device to the, “lower parts”.1
● Because power generation depends on, “... temperature difference between upper and lower parts ...”, the bottom needs to be cooler than the top.
● Anyone starting to see a problem? — How would you hold this thing? Thumb on the fingerprint spot at the top, fingers on the opposite side? This is demonstrated in the YouTube video. Since the temperature of your thumb is normally the same as your fingers, neither a flow of heat energy from top to the “lower parts”, nor generation of electricity seems likely. So, how can this work? The body is made of either aluminium or titanium. Heat will initially flow from the thumb spot into the metal of the light. With sustained use, the entire body of the light will warm up, reducing output. This may be compensated by energy stored in the capacitor.2
● Tritium vials described in the Gadgeteer article contain radioactive tritium gas in a tiny, glass vial lined with a chemical which fluoresces when exposed to the radiation produced by the decaying tritium.
● Tritium is a weakly radioactive element with a half-life of 12.3 years. Radiation produced by tritium is unlikely to make it through the glass walls of the vial.
● Half life is the time it takes for half of the atoms in a sample to radioactively decay. In the case of a glowing tritium vial, the brightness will halve in this time. It will halve again in the following 12.3 years & so on.3
__________1 “HOW DOES IT WORK? Lumen has relatively simple work principle - you touch TEG (Thermoelectric Generator) - small ceramic bar that can produce electric current when we provide temperature difference between upper and lower parts of TEG.” — https://www.kickstarter.com/projects/940015402/lumen-eternal-flashlight-that-doesnt-need-batterie/description
2 “... excessive power is stored in a capacitor to power Lumen whenever you need it.” — https://www.kickstarter.com/projects/940015402/lumen-eternal-flashlight-that-doesnt-need-batterie/description
3 Commonwealth of Pennsylvania, Department of Environmental Protection — “Facts about Radioactive Tritium” — https://www.ccpa.net/DocumentCenter/Home/View/3173
/ touch flashlight torch power Lumen flashlight flashlight external power source your body heat Kickstarter page touch TEG Thermoelectric Generator small ceramic bar produce electric current temperature difference between upper lower parts TEG difference between temperature your body 37 degrees C 98 °F environment 82 °F generate power single LED Metal body Lumen serves radiator temperature difference at least 16 degrees 15 mA 3v greater temperature difference additional energy capacitor later use titanium aluminum one 5mm ultra bright CREE LED phone screen aluminum flashlight torch 45 grams 1.6 ounces tritium vial Lumen glowing bar fingerprint area vial glow dark finding flashlight torch project fully funded torch flashlights backers aluminum version titanium version optional tritium vial /
