Development and experimental study of a fiber-optic SERS-based system for remote <i>in-situ</i> detection of aquatic pollutants

Abstract To address the challenges of delayed pollution detection and passive responses in traditional water environmental management due to manual inspections, this study presents a fiber-optic surface-enhanced Raman spectroscopy (SERS) system for in-situ water pollution monitoring. The system uses a silver film flat-end fiber-optic SERS probe as the sensing unit, with multimode fiber-optic as the medium for remote transmission of SERS signals, enabling long-distance detection of water pollutants. A verification system was designed using a Renishaw micro confocal Raman spectrometer, and its performance was tested with malachite green (MG), a model organic pollutant. Results indicate that the system can detect MG at concentrations as low as 10 − 9 M in laboratory samples. For real river water samples, a 20 m fiber-optic length enables stable detection of 10 − 8 M MG, meeting national standards (DB13/T 1358–2011). SERS signals remain stable within a 35 m fiber-optic range.