LEDs Could Replace Mercury Lamps in UV Sterilization Devices

Ultraviolet light can safely sterilize food, water and medical equipment by disrupting the DNA and other reproductive molecules in harmful bacteria. Though mercury lamps have traditionally supplied this UV light, there has been discussion of the harmful effects of mercury release from power generation. A potentially energy-efficient and non-toxic alternative is the light-emitting diode, or LED, which can emit light at almost any desired wavelength.

LEDs are more rugged and operate at lower voltages than glass-containing mercury bulbs. Thus, LEDs are more compatible with portable water disinfection units, which could also be solar-powered and used in situations where centralized facilities are not available, such as disaster relief. LEDs currently require a great deal of electricity to produce UV light, but researchers from around the world are focused on improving this efficiency.

LEDs are semiconductor devices that operate in much the same way as the tiny elements on a computer chip. The difference is that some of the electrons flowing into an LED are captured and release their energy as light. Because these are solid materials rather than gas-filled bulbs, LEDs are more compact and durable than alternative light sources. The first commercial LEDs were small red indicator lights, but engineers have developed new materials that emit in a rainbow of colors. Nitride-based LEDs are the most promising for pushing beyond the visible into the ultraviolet. Some of these UV LEDs are already being used in the curing of ink and the testing for counterfeit money, but for sterilization, shorter wavelength light is required. These short wavelength, or “Deep UV” LEDs, present a number of technical challenges and are predominantly implemented in highly specialized disinfection systems in industrial and medical applications, as well as other non-disinfection markets.

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