Teams from Princeton University and the U.S. Naval Research Lab have developed a new sensor that detects methane in low concentrations. This new sensor relies on an interband cascade light-emitting device (ICLED), which emits light at mid-infrared (IR) wavelengths, to detect methane concentrations in the neighborhood of 0.1 parts per million.
The new sensor measures IR light transmitted through clean air against IR light transmitted through air containing methane. To enhance sensitivity, IR light from the ICLED was directed through a 1 meter, long hollow-core fiber featuring an air sample. With a coating of silver inside of the hollow core, the light reflected off the fiber’s surfaces and traveled along the fiber to reach the photodetector at the opposing end. According to the research, this enabled the light to interact with other molecules of methane in the air, thus allowing increased absorption of the light. During testing of the sensor, known concentrations of methane were fed into the hollow core fiber and the team measured the IR transmission of the samples alongside laser-based sensors. According to their findings, the ICLED sensor detected concentrations around 0.1 parts per million.
It was suggested that a network of the new sensors could be used to monitor emissions near sources of methane pollution, such as on oil and gas platforms or in large facilities, to quickly detect leaks. The team expects to enhance the design of the sensor, and extend field measurements to potentially detect other gases in the future.
Read the complete findings here via The Optical Society journal: https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-29-5-7221&id=447915