Surface Plasmon Resonance Biosensor Based on STO and Graphene Sheets for Detecting Two Commonly Used Buffers: TRIS–Borate-EDTA and Dulbecco Phosphate Buffered Saline

Abstract

In this study, we present a new biosensor based on surface plasmon resonance (SPR) for the detection of two commonly used buffers: Dulbecco Phosphate Buffered Saline (PBS) and TRIS-Borate-EDTA Buffer (TBE). The proposed SPR sensor utilizes a combination of SrTiO₃ (STO) and two-dimensional (2D) materials. In the angle interrogation method, using STO can almost double the sensitivity compared to using traditional SPR biosensors. Moreover, using a single sheet of graphene (SSG) can further improve the sensitivity. For PBS and TBE buffers, the highest sensitivities reached are 327.023 and 320.581°/RIU with the structures SSG/35 nm Ag/ 14 nm STO and SSG/50 nm Ag/12 nm STO, respectively. We also investigate a set of 2D nanomaterials and found that the maximum sensitivity can be attained with WSe₂ due to its lower real part of the refractive index. The results reveal that the proposed SPR biosensor is an efficient tool for biomedical applications.