Investigation of the profile effect on the sensitivity enhancement of nanowire-mediated localized surface plasmon resonance biosensors

Localized surface plasmon resonance (SPR) biosensors with metallic nanowires regularly patterned on a gold film are considered for sensitivity enhancement. The theoretical investigation was conducted using rigorous coupled wave analysis in terms of various design metrics, such as the resonance angle shift, the SPR curve angular width, and the minimum reflectance at resonance. The results show that nanowires of a T-profile present more effective sensitivity enhancement than an inverse T-profile. The sensitivity enhancement mediated by the presence of nanowires has also been clarified qualitatively based on the dispersion relation between metal film involving nanowires and surrounding dielectric medium. The study is expected to provide extremely high sensitivity in SPR-based biosensing. (c) 2005 Elsevier B.V. All rights reserved.