Sensitivity and figure of merit of core-shifted metal nanoring as biochemical sensor.

Identifying biological and chemical species is vital in many fields such as science, medicine, environmental monitoring, and food processing. Compared to many other methods, metal nanoparticle-based detection employing the shift of plasmonic resonance offers advantages like high sensitivity and simple instrumentation. The sensitivity and selectivity of biochemical species detection utilizing metal nanoparticles stem from strong light confinement and localization when metal nanoparticles are illuminated with UV or visible light. In this work, we investigate further enhancement in the detection sensitivity by using non-concentric metal nanoring. Core-shell structures like metal nanoring allow easy resonance wavelength tunability compared to solid nanoparticles. Non-concentric silver nanoring, modeled as a ring with a shifted core, shows the excitation of Fano-type resonances indicated by asymmetric extinction peak. The resonance wavelength is highly sensitive to tiny variations in the local refractive index. The radius of nanoparticles and the shift of the nanoring core were optimized numerically using the MNPBEM toolbox to obtain the highest detection sensitivity and figure of merit. The shift of the inner core of the ring increases the sensitivity and figure of merit. [ABSTRACT FROM AUTHOR]