Facile fabrication of hierarchical Al nanocap arrays for refractive index sensing

Abstract Nanostructure-based localized surface plasmon resonance (LSPR) sensing have great potential for refractive index (RI) detection in the area of life science, chemical and food safety. Recently, the studies of aluminum (Al)-based nanostructures for sensing have attracted a large attention because aluminum is a cost-effective material and have excellent plasmonic characteristics from UV to near-infrared ranges. However, the fabrication of Al nanostructures used for sensing mainly focus on lithography techniques which are complex, expensive. Here, a facile method for the fabrication of hierarchical Al nanocap arrays used as LSPR sensing device was investigated. By only controlling the deposited Al thickness onto barrier layer surface of anodic aluminum oxide (AAO) template, the hierarchical Al nanocap arrays with tunable plasmonic wavelength ranging from 331 nm to 428 nm were obtained. The RI sensitivity of 80 nm hierarchical Al nanocap array is 358 nm/RIU and shows a good consistency with the FDTD simulation result. The concentration detection limit of adenine aqueous and ethanol solution are 1 × 10 − 6 M and 1 × 10 − 5 M , respectively. The results provide a new approach for developing an inexpensive, efficient, and mass-produced Al nanostructure sensor.