Performance Improvement of an Au and TiO2 Coated D-shaped Photonic Crystal Fiber (PCF) Based SPR Sensor for Cancer Detection

Abstract

Surface plasmon resonance (SPR) has been an emerging tool for the recognition of cancer in a label-free manner. However, conventional SPR setups are based on prism coupling, which makes them bulky, hindering their capability to be integrated into compact and portable devices. To overcome these issues, the proposed approach introduces a photonic crystal fiber (PCF) structure with a micro-channel D-shaped, integrated with a gold (Au) coating as the plasmonic substance and titanium dioxide (TiO₂ ) as a dielectric substance. It minimizes the distance of the plasmonic film from the fiber core, thus elevating the sensor performance. In addition, the introduction of TiO₂ over the plasmonic film alters the plasmon-analyte interaction, thus increasing the sensitivity. The numerical simulation for the designed sensor is done in COMSOL Multiphysics software through the finite element method (FEM). After optimization, the sensor is numerically evaluated for the identification of six various carcinoma cell types for refractive indices between 1.360 an 1.401. The ultimate achieved amplitude and spectral sensitivities are 717.29 RIU^-1 and 7142.86 nm/RIU, respectively, recorded for MCF-7 and MDA-MB-231 cells. Additionally, the optimized sensor can distinguish a diverse array of biomolecules across the RI span of 1.330 to 1.420, attaining a peak spectral sensitivity of 20,000 nm/RIU for y-polarized light. Moving further, the sensor also delineated excellent figure of merit, resolution, and amplitude sensitivity values of 366 RIU^-1, 5×10^-6 RIU, and 1178 RIU^-1, respectively, within the mentioned RI domain. The measured outcomes show that the designed sensor could be a potential option for the precise identification of various cancer cells.