Au nanoparticles-based Localized Surface Plasmon Resonance Refractometer

A localized surface plasmon resonance (LSPR) refractometer based on Au nanoparticles (NPs) was demonstrated in this paper. By immobilizing Au NPs onto the inner wall of micro-capillary, a LSPR-based refractometer was obtained. This sensor was highly sensitive to refractive index (RI) and offers a wide dynamic detection range, and it was sensitivitie-tunable caused by the extinction efficiency of the Au NPs in the evanescent field of micro-capillary inner surface. Then the micro-capillary can be used as both a sensing element and a flow cell, so that micro-measurement can be achieved. The response of LSPR to RI was verified experimentally and the results demonstrated that the absorbance of Au NPs increases between 1.328-1.451, and decreases between 1.451-1.470 with the increasing RI. The sensitivities were 109.6%/RIU in the RI of 1.328-1.394RIU, 395.7%/RIU in the RI of 1.394-1.397RIU and 1035.7%/RIU in the RI range of 1.451-1.470RIU. This refractometer was cost-effective, small-size and highly sensitive to be used for refractometer and can be extended for other physical or chemical parameter measurement for further investigations.