A novel gallium phosphide-aluminium antimonide material based SPR sensor with enhanced evanescent field confinement for early detection of cancer biomarkers

In this study, a surface plasmon resonance (SPR) biosensor was designed to support early and accurate detection of breast and cervical cancer biomarkers. The sensor consists of a precisely designed multilayer structure that includes a BK7 prism, silver (Ag), gallium phosphide (GaP), and aluminum antimonide (AlSb) layers. The structure maximizes field confinement and plasmonic coupling, which are essential for sensing small changes in biological samples. This study investigates the thickness of the Ag layer by investigating various factors such as sensitivity, quality factor (QF), detection accuracy (DA), and Figure of Merit (FoM). Its performance was evaluated using angular interrogation and transfer matrix methods at 633 nm. The sensor performance was evaluated using cancer-associated analytes, such as MCF-7, MDA-MB-231, and HeLa cells, in which small changes in the refractive index (RI) were detected with high precision. The highest obtained sensitivity in this study is 339.83°/RIU, a QF of 120.80 RIU⁻¹ , a FoM of 116.70 RIU⁻¹ , and DA of 1.69 for the breast cancer (type-1) detection. This study demonstrates the high potential of the sensor for real-time, non-invasive clinical diagnostics, which is a major advancement in early cancer detection.