A change of surface plasmon resonance (SPR) characteristics due to fluids type variation as a basic study of biosensor

Abstract

SPR sensor is one of the detection devices based on surface plasmon resonance (SPR) phenomenon which can be used to identify biomolecular objects with high sensitivity and selectivity. This SPR phenomenon occurs at a certain angle, when incident light waves have superposition with evanescent waves and then reinforce each other on a metal-coated prism. In this study, the influence of fluid variation was analyzed using the SPR device as a basic study of SPR for biosensor application. The SPR device consists of semiconductor laser, prism, gold-plated chip sensor, stepping motor, photodiodes, and fluids variation as the detection objects. Fluids in this experiment are water, methanol, and ethanol. SPR angles were obtained of 61.418°, 63.070°, and 65.640°, for the objects of water, methanol, and ethanol, respectively. Meanwhile, the results of real-time detection produce different values of Response Unit (RU) due to different fluids. RU charts in real time reported the response unit of air, ethanol, methanol, and water of about 2,200, 1,100, 600, and 300, respectively. The results of three real-time measurements also show a stable RU value for each fluid. The SPR measurement records the change of the SPR curves due to different fluids because there are the refractive index differences of the fluids. The details of the SPR curve changes due to fluid objects are presented in this paper.