Rational Fabrication of Ag Nanocone Arrays Embedded with Ag NPs and Their Sensing Applications

Colloidal lithography is used to design and construct a high-performance plasmonic sensor based on Ag nanocone arrays embedded with Ag NPs. The surface plasmon polariton (SPP) of the Ag nanocone array and the localized surface plasmon resonance (LSPR) of Ag NPs inside the nanocones can both couple incident photons. Sharp reflectance troughs are considerably enhanced by coupling the SPPs and LSPR, which is made possible by carefully tuning the nanocone sizes. To maximize the line shape and sensitivity, other geometric factors, such as the thickness of the silver layer and the size of the Ag NPs, are modified. Finite-difference time-domain computations confirm these hypotheses and experimental findings. We use well-researched solvents with various refractive indices as a model system to demonstrate good sensing performance as a proof of concept. The crystal used in this investigation has the ideal refractive index sensitivity, having 500 nm lattice constant, 350 nm nanocone height, and 350 nm base diameter (aspect ratio = 1). The Ag nanocone array embedded with Ag NPs is a good contender for a sensing platform due to its compact structure and efficient read-out apparatus.