Low Refractive Index Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor

This paper presents a comparative study of highly sensitive plasmonic micro biosensors, focusing on gold-coated and silver-coated designs using dual-gist photonic crystal fibers (PCF). The study involves graphical and numerical analysis via COMSOL Multiphysics 6.1 simulation. To improve performance, the silver sensor is treated with a thin graphene layer to prevent oxidation, while gold is chosen for its chemical inertness and recyclability. The gold-coated sensor demonstrates maximum sensitivity of 1,15,999 nm/RIU and amplitude of 2450 RIU-l, with resolution values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8.66 \ \mathrm{x} \ 10-7$</tex> RIU. The silver-coated sensor shows 49,000 nm/RIU and 1876 RIU-l sensitivity, with a resolution of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.86 \ \mathrm{x} \ 10-6$</tex> and an FOM of 555. The sensors exhibit impressive metrics for refractive index sensing (1.29-1.39 RIU range), making them highly suitable for organic chemical sensing, biological detection, pharmacological assessments, and other analytical applications. Surface Plasmon Resonance (SPR) allows for studying molecular interactions, such as ligand-receptor binding and RNA-DNA interactions, by measuring changes in SPR angles. Despite advantages, conventional SPR sensors face limitations with traditional designs like Fiber Bragg Grating (FBG), prism-based, and fiber optic methods.