Fano-resonance-based plasmonic refractive index sensor with high sensitivity for detection of urea

Abstract

In the recent context of the post-pandemic world, label-free detection has become a crucial technique in various human physiological testing analyses. In this paper, a plasmonic nanosensor is proposed based on a tapered waveguide cavity resonator, which provides label-free detection with high sensitivity for bio-sensing applications. The transmittance curve is studied using the finite difference time domain method. The transmittance curve exhibits dual Fano resonances with the highest sensitivity of 2544.3 nm/RIU. The resultant simulated transmittance values are further validated by comparing them to the theoretical Fano line shape function. Further, the fabrication complexities have been investigated with respect to changes in geometrical parameters such as the change in width of the tapered waveguide and the height of the cavity resonators. Other performance parameters are also calculated such as FOM, Q factor, and detection limit, which come out at values of 40.54RIU−1, 41.7, and 0.024, respectively. Moreover, a biosensing application has been investigated by testing the detection of urea in a human urine sample.