Silicon nitride based fluidically tuned photonic crystal for bio-sensing application

In this work, silicon nitride (Si₃N₄) based fluidically tuned photonic crystal for a biosensing application is presented. The optical structure is designed on Si₃N₄ on insulator. The Si₃N₄ on insulator substrate is found to be one of the most promising materials for the design of bio- sensor at short wavelength. At short wavelength Si₃N₄ material is found to be most promising material for optical integrated circuits. The structure of the sensor consists of Silicon nitride input and output waveguides separated by a fluidically tuned photonic crystal. Fluidically tuned photonic crystal acts as a sensing region. The sensitivity is based on refractive index of fluidically tuned photonic crystal. The proposed sensor is designed to operate in the visible wavelength range of 660nm. Fluidically tuned photonic crystal consists of rectangular photonic crystal array. The holes of photonic crystal are approximately 160nm in diameter and height is 200nm. Organic light emitting diode is used as an optical source. OLED is coupled to input waveguide. The PDMS microfluidic channel is moulded on the rectangular photonic crystal structure. The structure is modelled and analysis is carried out by using Lumerical mode solution and Lumerical Finite Difference Time Domain (FDTD) simulation tools. Such devices if fabricated can be employed for early detection of various diseases related to pathological parameters.