Metal-insulator-metal plasmonic sensor utilizing grating-defect waveguide and cavities for temperature sensing and biological applications

Abstract

This paper proposes a novel plasmonic temperature and refractive index (RI) sensor that utilizes a Metal-Insulator-Metal (MIM) waveguide with two neighboring hexagonal cavities working based on Surface Plasmon Resonance (SPR). The study demonstrates that the structural parameters, including coupling distance and the number of gratings, have a substantial influence on both Full Width at Half Maximum (FWHM) and the transmission spectrum. The findings of this study demonstrated a maximum temperature sensitivity of 0.91 nm.°C−1 for carbon disulfide and a corresponding maximum temperature figure of Merit (FoM) of 0.0180 °C−1 for chloroform. The RI-sensitivity (RIS) of this sensor is found to be 1147.22 nm per RI unit (RIU) as well as its FoM is 37.1 RIU−1. Furthermore, the sensor exhibits the ability to quantify blood glucose concentration with a maximum sensitivity of 0.136 nm.g−1.L and measure blood plasma concentration with a maximum sensitivity of 0.211 nm.g−1.L. This sensor differentiates the RI between healthy and cancer cells and can be utilized to identify both healthy red blood cells and those infected with malaria. Adding gratings to the waveguide and within the hexagonal cavities has a significant impact on the transmission intensity. The proposed plasmonic sensor can be used in optoelectronics, cancer cell sensors and photonic circuits.