Experimental study of sensitivity enhancement in surface plasmon resonance biosensors by use of periodic metallic nanowires.

We have experimentally confirmed sensitivity enhancement of a nanowire-based surface plasmon resonance (SPR) sensor structure. Gold nanowires with periods of 200 and 500 nm were fabricated, respectively, by electron-beam and interference lithography on a gold/SF10 substrate. Sensitivity enhancement was measured to be 44% compared with a conventional thin-film-based SPR structure for nanowires of 200 nm period and 31% for 500 nm when evaluated using ethanol at a varied concentration. This result is consistent with numerical data. Surface roughness is responsible for sensitivity reduction by more than 10%. More significant sensitivity improvement can be achieved by inducing strong localized plasmon coupling with finer nanowires.