Performance Analysis of Au/ZrN Based Dual‐Core Low‐Loss Photonic Crystal Fibre Biosensor for Biomedical Applications

ABSTRACT The performance of a unique tunable low‐loss photonic crystal fibre (PCF)‐based refractive index (RI) sensor comprising Gold (Au) and Zirconium Nitride (ZrN) as the plasmonic layer is explored in this article. A comparative analysis of three sensor configurations—Au alone, ZrN alone, and a combination of Au and ZrN—is presented. The sensor achieves the highest spectral sensitivity (WS) of 18,010 nm/RIU at an RI of 1.40 using Au alone and 6150 nm/RIU at an RI of 1.39 using ZrN alone. When both materials are combined, an utmost WS of 38,915 nm/RIU is achieved at an RI of 1.39 for both polarisations, outperforming the other configurations with a confinement loss of only 0.551 dB/cm at an RI of 1.40. This low loss facilitates easy fabrication, allowing for a maximum sensor length of 159 cm, a resolution of 2.57 × 10 −6 RIU, and a limit of detection (LOD) of 6.603 × 10 −11 RIU 2 /nm. The bimetallic layer setup enables the opportunity for enhanced optical coupling between the two different types of plasmonic material used, elevating the detection capability of the sensor. The sensing performance displayed can outperform the currently available sensors that use ZrN solely and are very well‐compatible with those using Gold alone. However, using gold layer alone gave out better amplitude sensitivity (AS) results which makes it suitable for application when the cost of equipment is in question and the use of ZrN layer alone can also be a smarter choice considering the cost of material, durability and availability of Zirconium in nature when compared to Gold. The tunable sensor can be employed in biomedical applications such as monitoring the glucose level in the bloodstream of patients and detecting blood components such as RBC, WBC, haemoglobin, plasma, and water from blood samples with high precision and accuracy, being able to differentiate between potential interfering molecules.