Fluorescent lights may soon be a thing of the past: a team of researchers from the University of Illinois are developing panels of microcavity plasma lamps that could be used for residential and commercial lighting as well as for certain biomedical applications. "Built of aluminum foil, sapphire and small amounts of gas, the panels are less than 1 millimeter thick, and can hang on a wall like picture frames," said Gary Eden, a professor of electrical and computer engineering at the university and the corresponding author of the paper describing the technology.Similarly to conventional fluorescent lights, these microcavity plasma lamps are glow-discharges in which atoms of a gas excited by electrons radiate light. However, unlike the former, they produce the plasma in microscopic pockets and don't require reflector, ballast or heavy metal housing. In addition, the plasma panels are six times thinner than panels typically composed of light-emitting diodes.
Already brighter, lighter and more cost-efficient than traditional incandescent lights, Eden and his colleagues hope that they will approach or even surpass the efficiency of fluorescent lights with some further tweaking.
In general, a plasma panel consists of two sheets of aluminum foil compressed together and narrowly separated by a thin dielectric layer of clear aluminum oxide (i.e. sapphire) through which a small cavity, located at the center of each lamp, penetrates. "Each lamp is approximately the diameter of a human hair," said Sung-Jin Park, lead author of the paper. "We can pack an array of more than 250,000 lamps into a single panel."
The flat panels' radiating areas can produce uniform emissions of any color depending upon the type of gas and phosphor used, the authors attest. Their experiments showed that the plasma lamp's efficiency, known as luminous efficacy, could reach values exceeding 30 lumens per watt when the array design and microcavity phosphor were optimized. This is in sharp contrast to a typical incadescent light's efficacy, which ranges from 10 to 17 lumens per watt.
Employing a similar technology, the authors demonstrated the potential use of flexible plasma arrays sealed in polymeric packaging in several promising new areas, including as lightweight arrays to be mounted on curved surfaces such as the insides of windshields or as photo-therapeutic bandages to treat diseases driven into remission by particular wavelengths of light.
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