Sensitivity Enhancement of SPR Sensor with the Black Phosphorus and Graphene with Bi-layer of Gold for Chemical Sensing

Abstract

Surface plasmon resonance (SPR) based sensor has a great role in sensing applications in terms of real-time monitoring, label-free detection and repeatable measurements. Chemical produced in fruits during food adulteration is injurious to the health; hence, SPR sensors play a very important role in detecting these chemicals. In the present study, two-dimensional (2D) materials-based, such as graphene and black phosphorus (BP), optimized structure of the SPR-based chemical sensor with the increased sensitivity and better figure of merit (FOM) has been proposed. The finite element method (FEM) with the help of COMSOL Multiphysics software has been used for theoretical analysis. BK7 prism is coated with a bilayer of gold as plasmon active material, followed by black phosphorus (BP) and graphene, which works to enhance the evanescent field and also increase the performance of the sensor. The maximum sensitivity of the proposed optimized structure has been found 218 Degree/RIU for the 5×10-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$5\\times 10^{-3}$$\\end{document} index variation at the wavelength of 633 nm. The results obtained from the proposed structure show that the sensor can enhance the sensitivity for aqueous solution of the chemicals having the refractive index from 1.33 RIU to 1.36 RIU.