Enhanced Surface Plasmon Resonance Sensing Using Bismuth Ferrite and MXene Functional Layers

This study uses a bismuth ferrite (BiFeO3) and MXene (Ti3C2Tx) to design a surface plasmon resonance (SPR) biosensor for the sensitivity enhancement at a 633 nm wavelength. Here, MXene serves as a biorecognition element (BRE) layer to ensure stable and reliable biomolecule adsorption. The MXene is a family of two-dimensional (2D) materials with metallic-like conductivity, a large surface area that can attach biomolecules, and improve biocompatibility. The addition of a conductive 2D MXene layer and a high-index BiFeO3 dielectric layer greatly improves light–matter interaction and evanescent field penetration at the sensing interface. Strong plasmonic coupling is indicated by the reflectance analysis, which shows a distinct and consistent shift in the resonance angle as analyte RI increases. This study examined the sensitivity at optimized Ag and BiFeO3 layer thickness. At an Ag of 39 nm and BiFeO3 of 3 nm thickness, the maximal sensitivity of 340.68°/RIU with a remarkable figure of merit (FoM) of 47.38/RIU is obtained. The overall detection accuracy (DA) and FoM are significantly improved by the large sensitivity enhancement, despite a slight increase in full width at half maximum (FWHM). Furthermore, the penetration depth (PD) of 198.50 nm (at RI:1.330) and 199.52 nm (at RI:1.335) is attained with the proposed structure. Due to its high sensitivity, reusability, and reproducibility, the SPR biosensor has the potential to be used in biochemical, environmental, and medical detection.