In collaboration with an SME partner (please add here the hyperlink https://mirsense.com/), we have co-developed an advanced sensor for real-time ammonia detection in water using photoacoustic spectroscopy (PAS). This technique relies on modulated laser light, which is absorbed by ammonia molecules, leading to non-radiative relaxation and localized heating. The resulting periodic pressure variations generate acoustic waves, which are detected by a microphone within a photoacoustic cell. To enhance precision and efficiency, we applied advanced theoretical modeling, including the nonequilibrium Green’s function approach, to optimize the quantum cascade laser, which emits light at 9 microns.
The result is a highly sensitive and rapid-response system, capable of detecting sub-ppm ammonia concentrations in under 60 seconds, making it a powerful tool for continuous water quality monitoring. The sensor is ideally suited for near-real-time ammonia detection in settings such as water treatment plants and natural water bodies, where even small increases in ammonia levels can have serious environmental and health consequences.