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Technical Background

UV Disinfection

For over a century, ultraviolet light has been known as a highly effective means to destroy microorganisms in water, air and on surfaces.

Ultraviolet, or UV, light is the portion of the electromagnetic spectrum that lies beyond purple in the visible spectrum.  The UV spectrum can itself be categorized into three areas; UVA, UVB and UVC.  It is the latter UVC, which is found between the 200nm and 280nm wavelength range that we use for germicidal applications. 

UV light in the germicidal range is absorbed by DNA and has a peak effectiveness at around 260nm.  The absorption of UV light causes a disruption in the DNA chain of the microorganism which inhibits replication, rendering it harmless.

There are many benefits of UV disinfection including:

  • It is well established technique which is EPA approved
  • It is envornmentally friendly with no harmful chemicals
  • There are no known disinfection byproducts
  • There is no danger of overdosing
  • There are no changes to odor or taste
  • There are no effects on the minerals in the water

The technique is becoming widespread in high flow systems such as municipal and industrial water disinfection systems, where the method of generating the UV is by means of a special mecury lamp, which emits a broad spectrum of light with distinct UV peaks at 253.7nm and 184.9nm.  The latter wavelength is often filtered out as it a generation source of ozone. 

Mercury lamps are tube type bulbs, similar to fluorescent lamps, without the phosphor coating.  While they provide a solution for large scale applications, they have physical and operational limitations for systems operating at a smaller scale.

UV LEDs operating in the germicidal wavelength range will open a new set of markets in disinfection where the incumbent technology is not suitable.

UV LEDs

Light Emitting Diodes are small solid state light sources which have become ubiquitous in the visible wavelengths and can be found in applications ranging from small indicators in just about every piece of electronic equipment to large area signage and displays like those in Times Square.

Just as visible LEDs revolutionized the lighting and display industries, UV LEDs will revolutionize the disinfection industry.  UV LEDs have many benefits over current UV lamp technology:

  • They are small, but can be mounted in arrays to cover large areas
  • LEDs are mechanically robust and can be run from a low voltage power source, making them ideal for portable systems
  • Light from the LED is directional, so more photons can be directed onto the area for disinfection
  • LEDs emit a single wavlength of light, so there is no wasted energy or harmful ozone generation
  • LEDs are switchable; they can be turned on and off instantly
  • They are energy efficient
  • LEDs do not contain mercury, making them environmentally friendly

UV LEDs enable new opportunities in the disinfection market from military and disaster recovery systems, through faucet mount units that can be used in kitchens and hospitals to mainstream residential water filtration devices.

AlN Substrates

Germicidal UV LEDs are not commercially viable today and suffer from low powers and very short lifetime.  Poor performance coupled together with their high selling price make them inappropriate for applications in the disinfection markets.

Crystal IS believes that only UV LEDs based on our high quality AlN substrates will be commercially viable in the germicidal wavelength range and that this technology is the only route to high power, high efficiency UV LEDs.