Design and Analysis of Twin-Core Side-Polished SPR PCF Sensor for Preliminary Malaria Detection

This paper proposes a double-side polished twin-core photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor for early-stage detection of malaria. The analysis and the assessment of the proposed sensor are done by finite element method using the COMSOL Multiphysics software. The dual-side polished structure reduces the distance between the metal layer and core mode, thereby enhancing the sensor performance due to the strong coupling between them. The air holes arrangement resembles the shape of an “hourglass” which helps to confine light energy within the twin cores. A layer of gold, a preferred plasmonic material, is coated on the symmetrically polished surface of the PCF to induce SPR. Due to distinction in the refractive indices, the resonance wavelength is different for infected and normal red blood cells (RBCs). The analysis is done for infected RBCs (ring phase, trophozoite phase, and schizont phase). The structural parameters are optimized precisely and a maximum wavelength sensitivity of 26,428.57 nm/RIU was achieved for the ring phase, 16,052.6 nm/RIU for the trophozoite phase, and 12,586.2 nm/RIU for the schizont phase. The numerical analysis also shows that the sensor possess high figure-of-merit (FOM) values of 334.54 RIU⁻¹, 321.05 RIU⁻¹, and 381.40 RIU⁻¹ for the ring, trophozoite, and schizont phases, respectively. These results confirm the potential of the proposed sensor and also justify its betterment than the existing methods. Due to its promising sensing performance and appropriate FOM value, the proposed sensor is suitable for the early-stage malaria detection.