UV LEDs industry
development activity in many household applications has significantly increased. The resulting UV components from the DARPA CMUVT program will not only significantly improve size, weight, power and capability of chemical/biological-agent detectors, but will also allow the current development of consumer type systems to be realized in high volume markets.
Believed to be the largest market opportunity for UV LEDs, development has begun on LED-based point-of- use (POU) in-line water systems under NSF SBIR support. POU systems are designed to clean water on- demand in a small scale where it is to be (kitchen faucet, refrigerator dispenser, etc) rather than in a large centralized location. With fast turn on/off speeds, small footprint, low voltage operation and the ability to operate in cold environments, LEDs offer many advantages in this application space over traditional mercury lamps. However, mercury vapor fluorescent lamp technology is well established and for markets where size, turn on/off speeds and power requirements are not issues, it is unlikely that LEDs will replace this technology until later in their product life cycle. Instead, DUV LEDs will open new market opportunities that cannot be addressed with mercury lamps.
Previously HydroPhoton demonstrated UV LEDs in a portable on-demand water purifier which reduced the level of E-coli. by 99.99 percent in water flowing at a rate of 150 ml per minute. (“Brighter LEDs improve water purification rates”, Compound Semiconductor, Nov 14, 2005)Thanks to the support of the National Science Foundation (NSF), this work has been continued recently with high power DUV LEDs used to disinfect higher water flows. Traditional UV disinfection systems use far shorter 253.7 nm light, as this is the wavelength attainable using mercury lamps. However, it is widely known in the field that 265 nm is the peak wavelength of absorption of DNA, and practical analysis has shown that 275 nm is the most effective wavelength for eradicating pathogens such as E-coli. in water (see Figure 4). This wavelength shift is due to the absorption of water, which increases as the wavelength becomes shorter.
DUV LED water disinfection systems employing 275 nm sources have been produced. The systems, which feature our 275 nm DUV LED lamps, have been tested for E-coli. and MS2 disinfection at flow rates of 0.5 to 2 liters per minute. The water purification chamber, 3-inches in diameter and 6-inches long, was tested with 34 mW of DUV LED optical power (<4.5 W of electrical power ). E-coli. was now reduced by 99.99 percent in water flowing at a rate of more than 1 liter per minute. These results are encouraging, and further gains in this direction in DUV LED performance and water disinfection chamber designs will soon open up new market opportunities in point of use applications that can benefit from LED advantages.
© 2011 Angel Business Communications. Permission required.
January / February 2011
www.compoundsemiconductor.net 41
Applications for Deep UV LEDs
Protein Analysis Medical Diagnostics Drug Discovery End Point Detection Blood Gas Analysis Petro-Chemical Analysis Gas Detection Bio-Threat Detection Phototherapy UV Curing Water Disinfection Air Disinfection Surface Disinfection
SET’s UVClean LED-based water
purification chamber
Templates for Blue and UV LEDs GaN, AlN, AlGaN, InN, InGaN
World leaders in development of Hydride Vapour Phase Epitaxy (HVPE) processes and techniques for the production of novel compound semiconductors
•Templates •Wafer size: 50mm-150mm •Research grade InGaN wafers •Custom design epitaxy •Contract development
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Email:
plasma@oxinst.com Technologies and Devices International Tel: +1 301 572 7834
www.oxford-instruments.com/tdi3
Wide range of materials (GaN, AlN, AlGaN, InN and InGaN) on different sizes and types of substrates (sapphire or SiC)
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