The working principles of plasmonic noble metal sensors

In this thesis, the working principles of plasmonic noble metal-based sensors particularly those employing gold (Au) and silver (Ag) nanoparticles have been comprehensively investigated. Plasmonic noble metals possess the ability to detect minor changes in the local refractive index due to collective oscillations of surface electrons, making them critical components in the development of high-sensitivity detection systems. In this context, two key optical interaction mechanisms commonly utilized in sensor designs, namely Surface Plasmon Resonance (SPR) and Localized Surface Plasmon Resonance (LSPR), have been discussed in detail, with a particular focus on the structure, fabrication, and optical response of LSPR based sensors. Gold and silver nanoparticles were deposited on glass substrates using the Pulsed Laser Deposition (PLD) method. The morphological and optical properties of the produced surfaces were characterized using various techniques including SEM, EDS, UV-Vis-NIR spectroscopy, and FTIR analysis. The prepared sensor surfaces were exposed to biotin solutions of varying concentrations, and their spectral responses to refractive index changes were recorded and analyzed. The results demonstrated that LSPR peak shifts were directly related to molecular binding on the nanoparticle surfaces, and these shifts were used as a measure of sensor sensitivity.