Journal of Applied Sciences and Nanotechnology

Abstract

Nanoplasmonic sensing, based on the plasmonic resonance absorption of thin, irregularly-shaped Au nanostructures film, with a starting thickness of about 15 nm (±3 nm) sputtered on a quartz substrate, is used to monitor the CeO₂ NPs (with an average diameter of 50 nm) film refractive index variations using different film thicknesses (90 nm, 146 nm, 172 nm, and 196 nm). Increasing the film thickness of solution-processed CeO₂ NPs film, with layer-by-layer deposition on top of Au nanostructures, shows a significant redshift in the plasmonic resonance absorption of the plasmonic metal, from 580 nm to 611 nm. Such an increase is related to the change in the building microstructure of the semiconductor’s film which is reflected in changing its refractive index. Plasmonic surface refractive index sensitivity of 437.5 nm/RIU with FOM of 4.2 has been recorded. Such a sensing technique offers a large potential for developing cost-effective plasmonic nanosensing devices for clinical applications. This sensor structure is versatile and can be utilized to sense and monitor a large variety of materials and chemicals.