Microcapillary-Based Integrated LSPR Device for Refractive Index Detection and Biosensing

Abstract

A microcapillary-based localized surface plasmon resonance (LSPR) sensor with a wide dynamic refractive index (RI) detection range is reported in this paper. Au nanoparticles (NPs) are immobilized onto inner wall of microcapillary to achieve LSPR sensing. By establishing energy loss model of evanescent field, we research systematically optical characteristics of Au NPs in microcapillary evanescent field and sensing properties of LSPR sensor. Different from traditional LSPR sensor, special simulation and experimental results demonstrate that this sensor possesses a wide dynamic detection range and tunable-sensitivity due to extinction efficiency of Au NPs in evanescent field. In addition, hollow structure of microcapillary not only can be used as a sensing element but also as a fluid channel. It can reduce length of sensing region and realize extraction and detection of trace sample simultaneously, which is very helpful for achieving miniaturization and integration of sensing system. The proposed sensor can achieve a large dynamic RI detection range from 1.328-1.470 and offer favorable biosensing property with 3 nM detection limit for human IgG. It is cost-effective, miniaturized and integrated and potentially used for environmental monitoring and minimally invasive medical diagnostics.