Symmetrically etched plastic optical fiber sensor for the detection of ethylene glycol contamination in water

Human activities are increasingly contaminating surface and groundwater reserves. Among various pollutants, ethylene glycol (EG) contamination in water is particularly dangerous. At low concentrations it can enter the body undetected and causes serious health problems such as kidney failure and gastrointestinal disorders. This study demonstrates the use of symmetrically etched single-mode plastic optical fiber (POF) sensor model operating at 1550 nm for detecting EG presence in water using COMSOL Multiphysics. The working of the sensor is based on evanescent field interactions with surrounding medium to detect refractive index (RI) changes, while transmission variations through etched POF serving as the sensing metric. Simulations were conducted for aqueous EG solutions ranging from 0 to 0.15 weight fraction, corresponding to RI values ranging between 1.316 and 1.330. The sensor design was optimized by examining the impact of etched cladding diameter and etched length on sensitivity. These parameters were varied from 60 to 7.05 and 1 to 30 μm, respectively. This in turn lead to sensitivity values in the range of 0.39 × 10−3 to 99.50 × 10−3 Trans. (A.U)/RIU. Highlighting the importance of evanescent field-surrounding interaction for etched POF sensors, these findings revealed that sensitivity has direct relation with the length of etched region and inverse relation with cladding diameter. The maximum sensitivity of 99.50 × 10−3 Trans. (A.U)/RIU was achieved with a 30 μm etched length and 7.05 μm cladding diameter. The proposed POF-based sensor demonstrates strong potential for applications in biomedical engineering, biochemical monitoring, and beverage industry offering a compact and sensitive solution for EG contamination detection in water.