Plasmonic Biosensor for DNA Hybridization Using Integrated Graphene-Porous Silicon Waveguide

This work uses the full-vectorial finite element method to study a novel 3-D integrated graphene-porous silicon (p-Si) plasmonic waveguide-based nanostructure for deoxyribonucleic acid (DNA) hybridization. In this study, a p-Si waveguide is designed using the Maxwell Garnett model and is sandwiched between two low-indexed silicon dioxide (slot) layers. Next, a single graphene layer is deposited in both slot regions to enhance the sensor’s absorption, tuneability, and sensitivity. The extraordinary optical transmission (EOT) through subwavelength nanoaperture reduces the ohmic losses and improves the optical transmission near the infrared region. Moreover, to optimize the sensor’s design, a parametric analysis involving variations in the geometric dimensions of the sensor is performed using COMSOL multiphysics software. With 10% porosity of p-Si, the highest sensitivity value of 318.5 nm/RIU, 3.395/RIU figure of merit, 17.36 quality factor, and 0.01/nm detection accuracy with the presence of rectangular nanoaperture is achieved. Due to nanoscale size, the proposed label-free multilayer or hybrid plasmonic slot waveguide (HPSWG) biosensor offers the potential for future lab-on-a-chip (LOC) biological applications.