Enhanced the sensitivity of one-dimensional photonic crystals infiltrated with cancer cells

In this work, we use a one-dimensional photonic crystal as a biosensor composed of alternating GaAs and air layers. Within the cavity where they are infiltrated, the Normal, Jurkat, HeLa, PC-12, MDA-MB-231, and MCF-7 cells are bounded by layers of nanocomposite and graphene to increase biosensor sensitivity. The transmission spectrum was calculated using the transfer matrix method. We observed that, when the structural periodicity is broken, defect modes that characterize each cell are created. These defect modes move at a wavelength as the dielectric constant increases. Additionally, the separation between defect modes and bandwidth determines sensitivity, Q factor, and FOM, in which average values of 406.84 nm/RIU, 1765.53, and 535.44 were obtained, respectively, for normal light incidence. Regarding Transverse-Electric (TE) and Transverse-Magnetic (TM) polarization, the defect modes shift toward shorter wavelengths as the angle of incidence increases. For TE polarization, transmittance decreased and the distance between the modes increased. At a 50 degrees angle, sensitivity, Q factor, and FOM increased up to 497.55 nm/RIU, 3182.02, and 1401.25, respectively. Conversely, at a 50 degrees angle in TM polarization, sensitivity remained constant at a value of 407 nm/RIU, along with increased transmittance and decreased performance. Finally, sensitivity and performance were optimized by modifying the cavity thickness value at an incidence angle of 30 degrees for TE polarization, and at an incidence angle of 10 degrees for TM polarization. In both cases, the increased cavity thickness shifted the defect modes toward longer wavelengths while increasing sensitivity up to 495.75 nm/RIU for TE and 451.33 nm/RIU for TM.