Multiplex biomolecules-sensing: Simulation of an ultrasensitive sensor array for disease diagnosis via two-dimensional photonic crystals

This work presents promising topologies for a two-dimensional (2D) photonic crystal-based biosensor with multiple detection capabilities. Indeed, our investigation commenced with the simulation of an initial configuration containing a hexagonal lattice of silicon rods in the air, comprising three ring resonators positioned between two waveguides inclined at an angle of 60 degrees. As the diagnostic principle for any disease, the resonant frequency shift of the transmission spectrum of the bottom output port is considered when the analysis samples are inserted into the resonators. Four out of six diseases can be diagnosed by this structure with average sensitivity values. The initial structure undergoes adjustments, resulting in the formation of two distinct structures, each possessing improved sensitivity and the ability to detect three diseases. The first modified biosensor structure exhibited a sensitivity of 2200 nm/RIU in its capability to precisely detect symptoms of dengue fever, HIV, and diabetes. The second modified sensor structure succeeded in achieving a sensitivity of 5095.85 nm/RIU and showed remarkable ability in detecting three distinct forms of cancer: adrenal, blood, and cervical cancer. The simulation was carried out based on the 2D Finite-Difference Time-Domain (FDTD) approach, and the transmission spectra were extracted using MATLAB. Both sensor structures that have been proposed exhibit exceptional sensitivity to give multiple responses, rendering them highly effective and efficient in the field of diagnosis.