Design of a fabrication friendly & highly sensitive surface plasmon resonance-based photonic crystal fiber biosensor

Abstract We proffer in this research a distinctive, facile to fabricate, and highly sensitive photonic crystal fiber (PCF) biosensor based on the phenomenon of surface plasmon resonance (SPR). Our prototype has a strategic pattern of circular air holes inside the fiber, which leads to a superior sensing performance. The evaluation of all the sensor characteristics has been discharged by employing the finite element method (FEM) of COMSOL Multiphysics. The gold (Au) layer just around the fiber acts as the plasmonic material, and the TiO2 increases the adhesivity of the gold layer and the fiber. After the optimization of all the fiber parameters, we derived a maximum amplitude sensitivity (AS) and wavelength sensitivity (WS) of 5060 RIU−1 and 41500 nm/RIU, respectively, with a maximum sensor resolution 2.41 × 10−6 for wavelength and 1.98 × 10−6 for amplitude. Moreover, the maximum figure of merit (FOM) procured was 1068.7, and the maximum birefringence was found to be 1.568 × 10−3. The overall analyte sensing range is from refractive indices 1.32 to 1.43, and the sensor has a fabrication tolerance limit of ±10%. Additionally, our sensor's temperature and strain sensitivities are estimated to be 0.75 nm/°C and 3 pm/µe, respectively along with a resolution (temperature) of 1.33 × 10−1 °C. With its enhanced performance in terms of sensitivity, we believe that this SPR based PCF biosensor can potentially contribute to the detection of the unknown analytes and in applications of medical diagnostics.