Advanced SPR biosensor with optimized gold-TiO2 D-shaped photonic crystal fiber for precise multi-cancer detection.

In this paper, we present the design, investigation, and optimization of a surface plasmon resonance (SPR) biosensor using a D-shaped photonic crystal fiber (PCF) with layers of gold and titanium oxide (TiO₂). The TiO₂ layer is applied on top of the gold layer to enhance sensitivity. This biosensor aims to simplify the manufacturing process while achieving optimal performance through effective coupling. We improved the design by thoroughly analyzing and optimizing various structural parameters to enhance performance. Our biosensor demonstrated exceptional diagnostic accuracy when tested on multiple samples, including cancer cells (Basal, MDA-MB-231, Jurkat, PC-12, and HeLa). The biosensor achieved a maximum wavelength sensitivity (WS) of 42,000 nm/RIU, a maximum amplitude sensitivity (AS) of - 1862.72 RIU, and a maximum figure of merit (FOM) of 1393.128 RIU⁻¹ across the wavelength range from visible to near-infrared and within a refractive index (RI) range of 1.3-1.4. The results indicate that this optimized biosensor exhibits reliable and accurate detection capabilities, capable of measuring minute changes in RI with high precision.