Design of 2D photonic crystal biosensor to detect blood components

Photonic crystals are periodic structures made of insulators. They are the best option to design biosensors. In this paper, a photonic crystal biosensor containing insulation rods in the air was designed and simulated. This biosensor was used as a photonic crystal circular nano-ring between the internal and external waveguides. At the end of the internal waveguide, a defect exists to create an increase in the coupling distance. This causes the quality factor and resonant wavelength displacement to increase. The purpose of designing this sensor is to check blood ingredients. After connecting to a measuring rod, this sensor shows different refractive indices. Another important characteristic of the proposed structure is that most radiuses of dielectric rods are identical. This causes the sensor construction to be easy. The plane-wave expansion method is utilized to calculate the band structure. The results show that a photonic band gap with a wavelength from 1.26 to 1.92 \(\mathrm{\mu m}\) is created at this distance where no wavelength can spread. In this work, the Q-factor, detection limit, figure of merit, and sensitivity of the proposed photonic crystal were recorded as 5166, 0.021RIU⁻¹, 9.84 nm/RIU, and 2.94 nm/RIU.