Structure Effect on Sensitivity of Gold Nanoslits Studied by Spectral Integration Method

Abstract

Gold nanoslit arrays have multiple resonances due to localized plasmons, Bloch wave surface plasmon polaritons, and Wood’s anomaly. Different structures result in different resonances and affect the detection sensitivity of the nanoslits. We systematically compared different structure parameters such as period, slit widths, and gold film thickness by using a spectral integration method. The experimental results show the detection sensitivity had an optimal value for a 500-nm period and 130-nm-thick nanoslits. Moreover, the sensitivity increases with the decrease of the slit widths. It was improved about three times when the size was reduced from 230 to 56 nm. The optimized structure can achieve a detection limit of 5 × 10−6 refractive index unit when the stability is 0.2%. Combining multispectral images and the spectral integration method, we demonstrate real-time and multiple detections of antigen–antibody interactions.