Numerical Analysis of Multifunctional Biosensor with Dual-Channel Photonic Crystal Fibers Based on Localized Surface Plasmon Resonance

A multifunctional biosensor composed of a dual-channel photonic crystal fiber (PCF) based on localized surface plasmon resonance (LSPR) is presented to measure dynamic changes in the magnetic field, temperature, and analyte refractive index at mid-infrared wavelengths. The finite-element method (FEM) is used to model and determine the sensing properties of the sensor. The flat dual-channel surface is coated with a gold film, and two nanowires are put on the fan-shaped openings to create directional resonance coupling to detect the analyte refractive index and temperature. By utilizing that the refractive index (RI) of the filled magnetic fluid (MF) is sensitive to the external magnetic field and temperature, a sensor with multi-physical detection functions is obtained. For refractive indexes ranging from 1.47 to 1.52, the maximum sensitivity is as high as 31,000 nm/RIU, with a resolution of 3.22 × 10−6 RIU. The maximum sensitivities for the magnetic field and temperature are 1970 pm/Oe and −5500 pm/°C, respectively.