Surface plasmon resonance sensor with 2D materials for enhanced refractive index detection of chemical pollutants in seawater

Abstract

This paper introduces a highly sensitive, graphene-based, multilayer surface plasmon resonance (SPR) refractive index sensor is designed for the detection of chemical pollutants in seawater. The sensor structure consists of multiple layers, specifically BK7 glass, Chromium (Cr), Copper (Cu), MXene, and Graphene. SPR sensors have gained significant attention in the field of real-time chemical sensing due to their label-free detection capabilities, high sensitivity, and excellent reproducibility. In this sensor design, the refractive index (RI) of the sensing region is altered by the interaction of chemical pollutants present in the seawater. These variations in RI directly affect the excitation of surface plasmon polaritons (SPPs) at the multilayer sensor interface. This interaction forms the basis for detecting chemical pollutants, as changes in RI modulate the sensor's optical response, which can be accurately measured. The performance of the proposed sensor is thoroughly evaluated using numerical simulations based on the Transfer Matrix Method (TMM). The simulations are carried out over a refractive index range of 1.329–1.433, covering the typical RI variations caused by chemical pollutants in seawater. The sensor demonstrated exceptional performance, achieving a maximum sensitivity of 186 deg/RIU at an operational wavelength of 633 nm. Additionally, the sensor is exhibited a high detection accuracy (DA) of 1.5 deg⁻¹ and a figure of merit (FOM) of 205 RIU⁻¹, highlighting its ability to precisely distinguish small changes in refractive index. These results emphasize the potential of this graphene-based SPR sensor configuration for high-performance detection of chemical pollutants, making it an excellent candidate for environmental monitoring applications. Its robust design, combined with its high sensitivity and accuracy, positions it as a promising solution for addressing challenges in seawater pollution detection and monitoring.