Gold Nanoparticle-Enhanced D-shaped Optical Fiber Sensor for Mercury Ion Detection

Mercury ions (Hg2+)are highly toxic heavy metal ions, posing serious health risks to humans when present above safe concentrations1–3. Therefore, the development of a rapid and effective Hg2+ detection method is of significant importance. In this study, based on surface plasmon resonance (SPR) technology integrated with COMSOL simulation analysis, a highly sensitive and selective Hg2+ sensing system is constructed. Initially, the gold nanoparticles and the surface of the fiber optic gold film are modified by sodium sulfide (Na2S). In the presence of Hg2+, the modified sulfur ions specifically bind to Hg2+, forming a composite structure Au/S-Hg2+-S/AuNPS. Due to the strong electromagnetic coupling between gold nanoparticles and the gold film, a significant SPR wavelength shift occurs. Experimental results demonstrate the high sensitivity of the sensor to Hg2+. The fiber optic SPR transducer exhibits enhanced selectivity towards Hg2+ ions and high recovery rates in real environmental samples. This sensing system provides an alternative method for rapid and accurate determination of mercury content.