U-shaped plastic optical fiber sensor for phosphate detection in water

Evanescent wave optical fibre sensors have attracted a lot of attention for the detection of chemical species due to their sensitivity, selectivity, and repeatability. In addition, plastic optical fibre sensors are inexpensive, simple to fabricate, and not only act as sensors, but the same fibre can also be used to transport sensor signals. The fibre sensor’s sensitivity can be increased by removing the fibre cladding partially or fully. Also, different geometries have been reported to enhance the sensitivity of fibre sensors even more. In this paper, we report a U-shaped optical fibre sensor that utilises evanescent wave absorption as its primary mechanism for determining phosphate concentration in water. The U-shaped geometry offers enhanced sensitivity as compared to straight geometry. The developed U-shaped plastic optical fibre probe demonstrates impressive linear performance, which is evident in its remarkable regression coefficient of 98.48% and sensitivity of 0.0991 O.D./ppm. Due to their distinct features, plastic optical fibre sensors pave the way for improved water quality monitoring and analysis, which presents a vital contribution to both the industrial and environmental domains.