A Surface Plasmon Resonance Bio-Sensor Based on Dual Core D-Shaped Photonic Crystal Fibre Embedded With Silver Nanowires for Multisensing

In this paper, for sensing and monitoring the biochemical analyte dissolved in liquid, antigen-antibody interaction or protein-DNA/RNA binding process, we design a surface plasmon resonance refractive index based biosensor by using a dual core D-shaped six-fold photonic crystal fibre which is embedded with silver nanowires for multi-detection. We numerically analyze both the dispersion relations and the loss spectra for various analytes by finite element method. This optical fibre bio-sensor monitors the changes of the refractive index for different analytes by measuring the spectral shifts of the fibre loss peaks at their resonance wavelengths. With the wavelength interrogation method, we find that the proposed biosensor with two sensing channels exhibits a maximum refractive index sensitivity of 3400 nm/RIU and a resolution of 2.94\times 10^{-5} RIU for a large sensing range from 1.35 to 1.50, which covers most known analytes of proteins, viruses or DNA/RNA. By utilizing 200 nm silver nanowires in the sensing channels, the sensitivity can be enhanced up to 4000 nm/RIU. Due to its special two-channel design for multi-sensing, it is possible to distinguish/study the binding possibility/capability of unknown analyte with two different target proteins simultaneously. Further, by introducing another critical channel, the confinement loss for either channel I or channel II can be greatly enhanced for high accurate result and more reliable sensing. Moreover, we numerically prove that the diameter of nano silver wires has great influences on the sensing peaks and sensitivity of the proposed biosensor.