Enhanced refractive index sensor based on annular porous silicon 1D photonic crystal for pathogen bacteria detection

This work presents a novel approach for pathogen identification using a one-dimensional annular photonic crystal (APC). The APC structure consists of alternating silicon layers with varying porosities arranged in a periodic pattern. A defect layer has been incorporated for the detection and monitoring of <i>E. Coli</i> bacteria. The optical characteristics of the APC are analyzed by solving Maxwell’s equations and employing the modified transfer matrix method in Cartesian coordinates. The proposed APC design, which features a configuration of (layer a/layer b)<sup>N</sup>/defect layer/(layer a/layer b)<sup>N</sup>, demonstrates promising potential for pathogen detection when using water and <i>E. Coli</i> samples in the defect layer alongside porous silicon in a multilayer stack. All design parameters are meticulously optimized to achieve peak sensor performance. Various performance metrics, including resonant peak position, quality factor, figure of merit, and sensitivity, are calculated. Numerical simulations and theoretical analyses provide insight into the interaction between pathogenic microorganisms and the APC. This research contributes to the development of sensitive and effective optical sensing technologies for pathogen detection across various applications. Our design achieves a sensitivity of 231.4 nm/RIU and a quality factor of 667.5.