▎ 摘　　要

Recent advancements in nanotechnology have made it feasible to excite, control and tune Fano resonance in plasmonic nanosystems, especially through structural and material engineering. Because of various applications in areas such as refractive-index sensing, surface enhanced Raman scattering, and biosensing among others, considerable attention has been devoted to increase the sensitivity of Fano resonance based sensors. In this article, the formation of Fano resonances in graphene-assisted concentric nanoshell and nanomatryoshka is investigated using Mie theory, and the results have been validated using FEM-based COMSOL Multiphysics. It is shown that Fano resonances strongly depend on the chemical potential of graphene and the refractive index of the embedding environment. This makes these nanoparticle systems ultrasensitive sensors for sensing food adulteration. Refractory nitrides (e.g., ZrN and TiN) based plasmonic nanoshell and nanomatryoshka sensor designs optimized for maximum sensitivity are proposed with sensitivity up to 799.02 nm/RIU, representing a 120% increase in the sensitivity from the previous highest reported values. The present work paves way for developing highly sensitive Fano resonance based sensors with applications in diverse fields.