Design and optimization of grating based D-shaped PCF-SPR sensor through Taguchi method for RI-based blood cancer sensing

Abstract

A highly sensitive surface plasmon resonance (SPR) sensor is proposed and numerically investigated for blood cancer detection. The presented sensor is based on photonic crystal fiber (PCF) and employs a silver plasmonic grating. In the proposed structure, the D-shaped geometry has been utilized, which enhances the evanescent field interaction and improves the core and surface plasmon polariton (SPP) mode coupling. The refractive index (RI) of the analyte is varied from 1.362 to 1.390 to investigate the RI dependent sensing response of the proposed structure. The selected RI range is considered for RI based biomedical sensing relevant to blood cancer related applications. The simulations are performed on COMSOL Multiphysics software using Full-vector finite-element-method (FEM) to analyze the performance parameters. Local optimization of structural parameters is carried out to improve the sensing response, and the Taguchi method is further employed to study the impact of geometrical parameters on the sensing performance of the sensor. The proposed sensor achieves a wavelength sensitivity of $\mathrm{35,000}\text{nm/RIU}$ with a maximum amplitude sensitivity (AS) of $499.26{\text{RIU}}^{-1}$, and minimum resolution of $2.86\times 10^{-6}\text{RIU}$ indicating that the suggested sensor is highly sensitive and offers very good resolution. Furthermore, the evaluated resonance linewidths give FWHM values in the range of 128–182 nm, with a maximum figure of merit (FOM) of $192.31{\mathrm{RIU}}^{-1}$ at $n_a=1.380$ making it a promising sensor for blood cancer sensing and other biomedical sensing applications based on RI sensing.