Effect of size and position of silver metallic ring on the performance of optical nano biosensor based on coupled rod-ring nanostructure

In this paper, a coupled silver rod-ring nanostructure is proposed for tuning the LSPR wavelength of the plasmonic nanostructure, and the effect of various factors including the length and thickness of the silver ring, as well as the position of the ring on the optical response of the nanostructure is investigated. The results confirm the significant effect of the rod-ring coupling and the wide tunability of the nanostructure LSPR wavelength by changing the position of the ring. Studying the impacts of ring length and ring thickness on the optical response of the nanostructure also shows the importance of choosing the factors. The use of this nanostructure as a biosensor for oral cancer detection indicates that the sensitivity of this nanostructure is a function of the length and thickness of the silver ring as well as the location of the silver ring. However, the sensitivity of the nano biosensor depends on the ring length more than the ring thickness.