Dual-substrate SERS sensor based on optical fiber for ultra-sensitive detection of organic pollutants

In this study, what we believe to be a novel approach is presented whereby D-shaped polarization-maintaining photonic crystal fiber (PM-PCF) surface-enhanced Raman scattering (SERS) sensors are incorporated with a Raman spectrometer to achieve high sensitivity for the detection of organic pollutants (2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and nitrobenzene (NB)). The PM-PCF SERS probe was fabricated by applying a gold nanolayer of 40 nm thickness to the surface of the D-shaped fiber end. The organic pollutant-induced SERS signals are measured, and the sensing performance of the proposed sensors is examined through experimental analysis. The optimized structure exhibited a five-fold enhancement in SERS signals for 2,3,7,8-TCDD and a four-fold enhancement for NB compared to the conventional reflection configuration. Different 2,3,7,8 TCDD and NB concentrations in solution were detected, with limits of detection (LOD) of 1.35 x 10 −11 M and 7.96 x10 −12 M, respectively. This sensor, which features a highly sensitive SERS-active gold surface, is expected to be useful for online analysis and environmental monitoring. In the second part of this study, zirconium nanoparticles (ZrO 2 NPs) were used to further enhance Raman signals in conjunction with a D-shaped PM-PCF sensor coated with a gold nanolayer. The ZrO 2 NPs intensify the electromagnetic (EM) field near the sensor's surface due to their unique optical and surface characteristics. The integration of the ZrO 2 NPs shows considerable potential for improving the performance of the D-shaped PM-PCF sensor in detecting trace amounts of organic pollutants with high precision. The dual-substrate SERS probe enhancement factor (EF) and LOD for 2,3,7,8-TCDD were 3.4 × 10 6 and 8.2 × 10 −12 M, respectively.