Comparative evaluation of Thiram detection by LSPR-based fiber optic probes with different nanostructures

In this work, we present an experimental investigation of highly sensitive optical fiber sensors utilizing localized surface plasmon resonance (LSPR), achieved by depositing gold nanoparticles (NPs) and nanostars (NSs) onto uncladded silica multi-mode fiber. NSs unique optical characteristics are explored in this configuration and spherical NPs are also examined for comparison. The sensitivity to surrounding medium refractive index was equal to about 440 nm/RIU for an LSPR generated by the NS, whereas in the case of NPs it was only 130 nm/RIU. As a case study, the sensors were also employed to detect Thiram, a widely used harmful agricultural pesticide, demonstrating a broad detection range from 10 nM to 100 μM and a significant wavelength shift up to 7 nm. This study underscores the simplicity, affordability, and superior performance of NS-based optical fiber sensors, positioning them as a highly promising solution for applications in environmental monitoring, biomedical diagnostics, and chemical detection.