Gold Ring and Graphite-Based Plasmonic Photonic Crystal Sensor for Biomedical Applications

Introduction: This research puts forward a cost-efficient high-efficiency plasmonic photonic crystal sensor for biomedical applications that functions in the near-infrared range. Methods: The sensor design is composed of multiple two-dimensional photonic crystal layers stacked in the order of SiO2 foundational layer, graphite layer, MgF2 waveguide, and finally a gold ring over the top. The graphite layer is deposited for optimum sensing and high absorption peaks and is state-of-the-art in this research work. Metal deposition of the gold layer is used for harnessing plasmonic properties that play a vital role in detecting small refractive index changes. Results: The sensor design is investigated for a range of coupling incident angles and it is found that the sensor is responsive to a broad range of angles i.e., 0o to 80o. The proposed sensor has given output peak values of more than 90% in the whole range of incident source angles. Conclusion: Finally, water and 25% concentration of glucose samples are used for investigating sensor performance and it is noted that the sensor’s sensitivity reaches as high as 1675 nm/RIU-1 with a Figure of Merit (FOM) of 20.94 RIU-1. The sensor’s numerical simulations have been performed using Finite Element Method (FEM) and Finite Difference Time Domain (FDTD).