Influence of EDTA Coverage Density on Optical Fiber Sensor for Heavy Metal Ion Detection

ABSTRACT Chelating agents have been extensively used for detecting heavy metal ions in optical fiber sensors. Although various studies have utilized different chelators to enhance the limit of detection, the uniformity of their coverage on the sensor surface is often underexplored. In this study, we used ethylenediaminetetraacetic acid (EDTA), a well‐known zinc chelator, to functionalize the surface of a single‐mode 28 optical fiber (SMF‐28). We then investigated the effect of EDTA coverage density on zinc ion detection. Experimental results revealed non‐uniform EDTA attachment along the fiber surface, leading to varying amounts of zinc binding in different regions. This uneven distribution significantly impacts the efficiency and sensitivity of optical fiber sensors in zinc ion detection. Our findings highlight the need to consider chelator coverage when designing and calibrating optical sensors for robust heavy metal ion detection.