Theoretical Investigation of an Ultrasensitive Label-Free SPR biosensor Based on AgGaS ₂ /Ag/BP/AlSb Multi-layered structure for Trace-Level Albumin Sensing

In this article, we propose an advanced Label-free surface plasmon resonance (SPR) biosensor for ultrasensitive trace-level albumin monitoring in urinary diagnostics. This study uses the Kretschmann configuration-based multi-layered structure with silver gallium sulfide (AgGaS 2 ), silver (Ag), black phosphorus (BP) and aluminium antimonide (AlSb). To analyse the sensor’s performance, the transfer matrix method is used along with the angular interrogation procedure at a wavelength of 633 nm. Initially, the optimization of Ag thickness and prism are explored by observing a better minimum reflectance and sensitivity performances. Subsequently, the key role of adding the proposed structure in the SPR sensor is shown by comparing the performance of other structures that categorized with the available layers. Furthermore, the performance analysis is executed with different layers’ thicknesses and found that the maximum attained parameters are a sensitivity of 704.7 °/RIU, quality factor of 101.03 RIU −1 , detection accuracy of 0.10. Also, the electric field intensity of the proposed sensor is observed with a significant penetration depth of 456.468 nm. This outperformed proposed sensor has a heavy weightage as compared with existing work in the field of biological and biomedical applications.