Optimization of copper and tin disulfide based surface plasmon resonance for the detection of brain tumor tissues

In this study, a surface plasmon resonance (SPR) sensor, including SF5 prism, copper (Cu), Tin Disulfide (SnS2), Molybdenum Ditelluride (MoTe2), and sensing medium (SM) layers, was designed for the detection of brain lesions. With the remarkable sensitivity of 142.15°/RIU found at 33 nm of Cu, 8 nm of SnS2, a monolayer of MoTe2, and refractive index (RI) of SM 1.33–1.50. To obtain the sensitivity of the proposed sensor, different brain lesions, including cerebrospinal fluid (CSF), gray matter, oligodendroglioma, low-grade glioma, lymphoma, and metastasis, were used as SM, while the thickness of the Cu layer was varied from 25 to 60 nm. A sharp SPR dip with a minimum reflectance (Rmin) of 3.9 × 10⁻⁷ a.u. was obtained at a thickness of 33 nm, which also yielded the highest sensitivity (S = 136.47°/RIU) and figure of merit (FoM = 15.01/RIU). The low full width at half maximum (FWHM) at this thickness and the SPR angle shift (Δθres) further confirmed the improved detection capability of the sensor. According to these results, the proposed SPR sensor is very useful for detecting brain abnormalities in real time and without labels.