February 8, 2008, Clayton, WI--Glow-paint company MPK Co. has announced a patent-pending microsphere material dubbed Litroenergy that generates its own light without electricity or sun exposure for 12 years (its half-life point). The mechanism for the glow is "betavoltaic," in which radioactive gas gives off "soft" beta emission inside encapsulated microspheres. The light source is non-toxic, and emits greenish-white light continuously equivalent to a 40-W light bulb without generating discernable heat, according to MPK co-founder Steve Stark.
The self-luminous micro particles, the radiation of which cannot penetrate the glass or polymer microsphere walls, can be injection molded or added to paint at a fill rate of approximately 20%. The Litrospheres are not affected by heat, sunlight, or cold, and are crush resistant up to 5,000 pounds. Furthermore, the material is inexpensive, costing $0.35 to light up an 8 x 11 x 1/8-in. sheet of plastic. The emission does not turn off, but gradually fades over a dozen or so years.
"As the material is bright enough to read by," claims Stark, "Litroenergy has potential to save billions in energy costs worldwide." Although mass production for supply to OEMs is only in discussion stages, the apparent front-runner application is safety, such as lighted safety tape, life rafts/flotation devices, and sports/camping equipment.
The company declined to elaborate on the mechanism of the light source, leaving unanswered questions about radiation levels and therefore safety. The inventor of Litroenergy, Michael P. Kohnen, II, also the president and CEO of MPK Co, emphasises that the material is non-toxic, and will not create toxic waste.
"The new material is non-toxic," writes Stark on a treehugger.com forum. "There is nothing radioactive about this material! NO TRITIUM in this material! This is Clean Energy Free Lighting." In contrast to this, Kohnen's patent application describes the radiation source as tritium, a soft source of beta emission, encapsulated in glass microspheres with phosphors. The emission is strong enough to cause the phosphor inside the microspheres to glow, but does not penetrate glass.
The invention beat out hundreds of other entries to capture the $20,000 grand prize in NASA TechBrief's Create the Future Design contest.