Ultra-high-sensitive biosensor based on SrTiO3 and two-dimensional materials: ellipsometric concepts

We propose a new Kretschmann configuration-based SPR biosensor using the combination of SrTiO 3 (STO) and two-dimensional (2D) materials. Using STO and single-layer graphene (SLG) enhanced the sensitivity by about 187% compared to conventional SPR biosensors in the angle interrogation method. This enhancement is related to the 44 nm of silver/13 nm of STO/SLG structure with a sensitivity of 333.2 °/RIU and conventional Ag-based SPR biosensor has a sensitivity of 116 °/RIU. Although the highest achieved sensitivity is 409 °/RIU for the 40 nm of Ag/14 nm of STO but for biosensor applications, 2D materials are needed to act as a Biomolecule Recognition Element (BRE). Furthermore, numerical modeling of ellipsometry integrated with the SPR technique is used, and it showed extraordinary enhancement in the overall performance of the proposed biosensor. Firstly, using Ψ can help to enhance the quality factor (QF) of the 2D materials-based SPR biosensor by more than 50%. Furthermore, using differential phase from numerical modeling of ellipsometry, by providing the extraordinary sensitivity of about 32140 °/RIU, improve the sensitivity more than 270-fold compared to conventional Ag-based SPR biosensors. These results show that our proposed structure and method will be beneficial in biomedical applications.