Gold nanoring as a sensitive plasmonic biosensor for on-chip DNA detection

We report an on-chip nanosensor based on the localized surface plasmon resonance (LSPR) property of gold nanorings. The fabricated nanorings using nanosphere lithography showed highly tunable optical properties and were optimized to boost LSPR-based biosensing. The LSPR extinction spectra of the nanosensor agreed well with the theoretical calculations using a finite-difference time-domain model. Such an on-chip nanoring-based biosensor showed a refractive index sensitivity of 350 nm/refractive index unit with a figure of merit of 3.1 and was utilized to detect DNA in a real-time and label-free manner.