Sensitivity increment of one dimensional photonic crystal biosensor

Designing a high sensitivity device has been a research focus and a requirement in biosensor application. We found out that one of the way to increase the sensitivity of an optical biosensor device is to increase the interaction area between the target analyte and the sensing region of the biosensor device where the light propagates. Using a high quality-factor (Q) one dimensional photonic crystal (1D PhC) biosensor structure based on silicon-on-insulator (SOI) material, we showed here the increase in the device's sensitivity as we gradually increase the analyte interaction area with the device's sensing region, side by side until all area around the sensing region are utilized in the sensing. 3D FDTD simulation tool was used. Final sensitivity is increased by up to 500% — as compared to only utilizing the top part of the 1D PhC. Mode profile analysis of the waveguide shows and suggests that the evanescent field of the guided light and the slotted periodic holes can be exploited for sensing in all direction surrounding the PhC. Analysis of this technique is supported by the optical path length (OPL) of the Fermat's principle theory. This research's output is important in designing a high sensitivity PhC biosensor and also other related optical biosensor device.