Large Scale, Low Temperature Microplasma UV Lighting Tiles for Water Purification and Sterilization

Eden Park Illumination, Inc. performed research for the development and commercialization of lamps comprising large arrays of microcavity plasmas capable of generating light in the UVB and C wavelength ranges in a slim and flat form factor. UV light is an efficient light source for a number of chemical processes and disinfection methods available commercially. It is known to be extremely effective for neutralizing pathogens (bacteria, viruses, cysts) and drugs such as hormone regulators that are of increasing concern in municipal water supplies. The primary drawback of conventional UV light sources is their limited form factor and the environmental concerns regarding the use of mercury. Microplasmas are non-equilibrium, low temperature plasma sources and they have high power loading (several 100 kW/cm3) which enables them to excite gases and form UV-generating excimer molecules efficiently. Additionally, they contain no toxic substances and the microcavity technology enables them to be nearly as efficient as their mercury-containing counterparts. This Phase I program has been focused on leveraging low temperature, microcavity plasma technology developed at the University of Illinois and Eden Park Illumination to realize low temperature UV lamps that are flat and designed to have a scalable, slim form factor (total thickness less than ~5 mm). Each microcavity (having a diameter of a few tens of microns to a few millimeters) was fabricated on a window substrate by various microfabrication technologies, and its electric field distribution was tailored by various electrode geometries to reduce power consumption and efficiently excite Xe gas. Light tiles capable of producing up to 50 mW/cm2 at 172 nm (UVC) from Xe gas were demonstrated with a UV conversion efficiency higher than 20 % in Phase I, and Phase II will develop and demonstrate large scale microcavity UV lamps having areas up to one square foot and their power supplies well matched to the lamp. Commercial Applications and Other Benefits: Several other emitters capable of generating photons in various UVB and UVC ranges will be designed and demonstrated for water purification and disinfection.