Design and Analysis of Highly Sensitive Plasmonic Sensor Based on 2-D Inorganic Ti-MXene and SrTiO₃ Interlayer

Abstract

Using appropriate interlayers, the sensitivity and performance of conventional surface plasmon resonance (SPR) sensors can be improved in the Kretschmann configuration. In this article, nano-layered SrTiO3 is proposed as an interlayer, which besides protecting silver from oxidation, due to the high refractive index and zero loss in the visible region, increases field intensity and sensitivity. The use of the Ti3C2 Tx MXene layer also leads to better adsorption of biomolecules due to high binding energies and large area. Using structural engineering, we optimized the physical parameters of the device. The theoretical results show that the proposed sensor has a sensitivity of 301.2°/RIU which is 164% higher than the Ag-only sensor, a detection accuracy (DA) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.119^{\circ -{1}}$ </tex-math></inline-formula> , a quality factor of 35.84 RIU <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> , a detection range of 1.33–1.3377 and near-zero minimum reflectance for 43 nm Ag, 12 nm SrTiO3, and a monolayer of MXene. Therefore, the proposed sensor is promising to be used in diagnostic applications and portable biosensors. Although, we can reach the highest sensitivity and quality factor of 438.4°/RIU and 103.9 RIU <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> for 48 nm Ag and 13 nm SrTiO3 without any MXene layer for non-bio (other) applications. However, using 2-D materials such as MXene increases the adsorption efficiency of the biosensor. Furthermore, by using the reflectance intensity difference method, we reach the sensitivity of 8000%/RIU.