Metal–Organic Framework Based Fiber Optic Ammonia Sensor

Accurate and precise detection of ammonia in water is important, considering its harmful effects on human health and aquatic ecosystems. In this letter, we report a copper-based metal–organic framework (MOF) coated U-bent fiber optic sensor (U-FOS) for ammonia detection with the help of a green light-emitting diode–photodetector pair. This portable dip-n-detect sensor shows optical intensity changes for ammonium chloride concentrations in the range of 0.1–10 ppm, five times below the safe limit of 0.5 ppm in water. Thus, these MOF-coated U-FOSs hold immense potential for real-time assessment of ammonia for field applications.