UV-C for Gas and Liquid Monitoring Applications

UV-C is readily absorbed by certain gas and liquid molecules and is becoming a critical element in a growing number of gas and liquid sensing, detection and monitoring applications. These include systems for monitoring ozone levels and equipment used to analyze the nitrate levels in water. Silanna’s innovative epitaxy process, driven by years of research, delivers efficient and reliable UV-C LEDs that meet the requirements of both of these applications.

UV-C LEDs for Ozone Monitoring

Because Ozone (O3) in the atmosphere absorbs most of the sun’s ultraviolet radiation it is important to protecting human health. However, in high concentrations ground level ozone, commonly referred as smog, can be harmful to humans, animals and plant life. As a result, from national parks to urban environments and from industrial sites to processing facilities, understanding the concentration of ozone is an important feature of indoor and outdoor air quality monitoring systems.

It is ozone’s ability to absorb ultraviolet light with peak absorption at wavelengths firmly in the UV-C spectrum that makes deep UV LEDs the perfect technology for ozone monitoring systems. By combining 255 nm UV-C LEDs such as the Silanna SN3 series with a photodiodes or other sensors that measure the intensity of the UV-C light able to pass through air samples, the concentration of ozone in the air can be detected.

Outline of a UV LED-based ozone monitor

This approach offers highly accurate, stable and repeatable ozone detection performance, even at very low gas levels. It also ensures that the other gases don’t have an influence on the readings.

Silanna’s SN3 series UV-C LEDs offer very efficient 255 nm UV-C light sources and help ozone monitoring systems to operate at ultra-low power. This makes them suitable for remote locations that need to rely on batteries or solar power as well as integration with IoT (Internet of Things) applications.

UV-C LEDs for Nitrate Sensors

Whether caused by the run-off from agricultural land and gardens or waste from industrial facilities, nitrates can cause significant problems for aquatic life in our rivers and lakes and can be harmful to humans if they make their way into sources of drinking water. As a result, monitoring nitrate levels in water is an important requirement for managing and minimizing the impact of excess nitrate levels.

In addition, because they are also used as preservatives in meats and cheeses, understanding the level of nitrates is also important to the food processing industry.

There are several ways that nitrates can be detected in liquids. These include measuring the colour intensity of dyes created by combining chemicals with nitrites and electrical potentiometric techniques that measure the voltage difference between electrodes in a nitrate solution.

More recently, manufacturers of nitrate monitoring equipment have been looking at techniques that measure the absorption of UV light in a liquid. Such techniques have various benefits such as the fact they offer high levels of accuracy and repeatability, require less frequent calibration, and do not demand additional chemical reactions with the solution under test.

Outline of a UV-based nitrate monitoring system

The Silanna SF1 series UV-C LEDs with wavelengths in the region of 235 nm are particularly well suited to nitrate monitoring systems. Because these LEDs are very efficient light sources, UV-C based monitoring systems have ultra-low power consumption, making them suitable for portable monitoring solutions. At the same time, they offer a significantly more cost-effective and environmentally friendly alternative to more conventional halogen lamp-based monitors.