Highly sensitive cancer detection using an open D-channel PCF-based SPR biosensor

Surface plasmon resonance (SPR) is a technique utilized for the label-free detection of cancer cells. In this analysis, we introduce a photonic crystal fiber (PCF) designed with an open D-channel, featuring a layer of gold (Au) and titanium dioxide (TiO₂) as the plasmonic material. This effectively reduces the gap between the fiber core and the gold layer, resulting in improved performance. Additionally, incorporating TiO₂ between the gold and the silica substrate enhances their adhesion and contributes to a more robust structure. We conducted a comprehensive numerical analysis of the suggested biosensor utilizing the finite element method (FEM) integrated with perfectly matched layers (PML) within the COMSOL Multiphysics simulation tool. The design of this sensor is specifically intended for the detection of molecules with a refractive index (RI) varying from 1.25 to 1.43, achieving an impressive peak spectral sensitivity of 47,000 nm/RIU. For this purpose, we investigated RI values from 1.36 to 1.401 concerning six different cancer cell types. The highest spectral sensitivity is 5214.285 nm/RIU, while the amplitude sensitivity is -1481.1 RIU^{- 1}, which has been recorded for MCF-7 and HeLa cells. This proposed sensor shows improved amplitude sensitivity, signal-to-noise ratio (SNR), full width at half maximum (FWHM), figure of merit (FOM), and detection limit (DL) compared to existing biosensors, highlighting its potential for biosensing applications. Additionally, it is significant that according to the results, HeLa cells have a maximum resolution of 1.19 × 10^{- 5} RIU and a FOM of 350 RIU^{- 1}.