Power your UV-C Sterilization Designs

Don Baldwin, Technical Support Manager – Power, Sager Power Systems, Sager Electronics


Since the start of the Covid-19 pandemic, the drive for technological advances in sterilization and disinfection has increased dramatically

Click image to enlarge

Figure 1. UV-C light-disinfecting robot

The Ultraviolet (UV) disinfection equipment market is projected to grow from $1.3 billion in 2019 to $5.7 billion by 2027.  Applications for this market are found in a variety of areas such as water treatment, wastewater treatment, air treatment, food & beverage disinfection, and surface disinfection. 

We've witnessed the evolution of consumer-based products like personal UV sanitizing wands, disinfection lamps, and light sanitizing pods for mobile phones, remote controls, and tablets.  New industrial, medical and interactive kiosk products with integrated Ultraviolet C (UV-C) disinfection solutions built into the product are now in development.

Water treatment applications are the major market shareholder for UV-C sterilization equipment and are projected to maintain that position through 2027.  With the increase in industrialization throughout the world, air and water pollution has caused a decrease in the purity of the freshwater supply.  UV-C sterilization equipment helps to provide clean and safe drinking water to the increased population worldwide and treat irrigation water to eliminate plant pathogens such as bacteria, fungi, viruses, and nematodes to reduce the rate of food-borne illnesses.

UV disinfection equipment uses Ultraviolet C (UV-C), which is a short-wavelength (100-280nm) of light to inactivate or "kill" the virus or bacteria by destroying the outer protein coating and disrupting their DNA, leaving them unable to perform vital cellular functions. 

The UV-C light or UV lamp is produced by several different means and at varying wavelengths which allow for different uses. There is FAR-UVC which operates at a wavelength of 222nm and is reported to be safe for use while people are in the room. Mercury-vapor lamps use energy from the 254nm wavelength because scientists have found it to be most effective. UV-C LEDs, which are relatively new to this market, operate in the 260-280nm wavelength and are being investigated for many new disinfecting and treatment applications. Other products such as xenon lamps produce a broad spectrum of UV light that provides a combination of wavelengths found in the UV-A, UV-B, and UV-C ranges.

UV-C light is generally considered harmful to human skin and eyes.  It is naturally produced by the sun along with UV-A and UV-B, with little of the UV-B penetrating the earth's atmosphere and none of the UV-C getting through.  For this reason, most applications that use UV-C light are in enclosed systems like water and wastewater treatment, HVAC systems, and full room sterilizations where no humans are present.  The exception to this is FAR-UVC which is still being studied, but some scientists believe it to be safe with an energy threshold limit of 23mJ/cm2.  FAR-UVC does not penetrate the outer layer of the skin or eyes, so it does not cause any tissue damage and can be used for constant disinfection in areas where humans are present.

The effectiveness of the UV-C light to disinfect a surface or area is primarily dependent on distance and time. This is explained by one of Sager Electronics' leading power supply manufacturers, MEAN WELL, in their white paper UV-C Sterilization LED Light and LED Drivers. "A single UV-C LED that is about 2.5W can output 99.9% irradiance over a 5cm surface. Irradiance is the amount of flux energy or brightness over a surface. In other words, it can sterilize 99.9% of germs over the 5cm surface from a distance of 6cm. However, when the surface is a bit larger such as 10cm, the sterilization rate drops to 25%. To increase the sterilization rate, longer time is required."This is the case for all forms of UV-C light.  The effectiveness of the UV-C light diminishes as the virus or bacteria gets further away from the light or the area being disinfected increases and thus must be exposed for a more extended period of time to produce the desired result.

Click image to enlarge

Figure 2. UV-C light indoor air purifier

Another factor that needs to be considered is that the viruses or bacterium cannot be inactivated if it is not directly exposed to the UV-C light.  The inactivation of viruses on surfaces may not be effective due to blocking UV radiation by soil, such as dust, under a phone case, or other contaminants such as bodily fluids.

To use UV-C light for sterilization, the means of generating the light, the application for the light, the distance and time needed for sterilization, and the line of sight all need to be considered.  However, creating a device able to manage all these items takes more than just a light source. Many other components factor into the design, such as a power source (AC/DC power supplies, DC/DC converters, batteries), sensors, connectors, switches, thermal management (fans, heatsinks, thermal interface material, etc.).  This is where a distributor and custom solution provider like Sager Electronics, with their engineering design and purchasing teams, can provide the latest technology available to help complete the UV-C sterilization equipment design.

The two main components in UV-C sterilization equipment are the UV lamp and some form of control unit.  The control unit manages the overall electrical output of the UV lamp by controlling the intensity of the lamp and the amount of time the lamp is on or off at a minimum.  More intelligent controllers come with lamp change timers to notify the user when the lamp needs to be replaced, UV alarms, ozone detection, and trouble indicators.  Both the control unit and the UV lamp require some form of power to operate, and in some cases, the voltage needed to operate each component is different.  Different operating voltages can be achieved in several ways depending on the main power source for the equipment.  If the equipment operates off of an AC/DC source, such as plugging into the wall outlet, then a multiple output supply can be used, or a single output supply can be used in conjunction with DC/DC converters to provide the various outputs necessary.  If the sterilization equipment operates off a battery source, then DC/DC converters would again be the best option to provide the additional output voltages required.

Intelligent controllers can also be used to control more intelligent power supplies such as LED drivers with dimming capabilities or AC/DC power supplies and DC/DC converters with PMBus capabilities to control the amount of power being provided to the UV lamp to control the intensity as well as turning the output on and off to provide blasts of UV-C light rather than continuous operation.

Sager Electronics has a world-class offering of power supplies along with a national team of power specialists and custom solutions and value-add capabilities that can assist a design engineer in the design and manufacturing of their UV-C sterilization equipment.

Sager Electronics