“…Improvement in sensitivity by substituting the simple PSi Fabry–Pérot interferometer with sophisticated multilayered-optical structures has already been vastly established, and research work in recent years has focused on optimization of these complex structures for improving their sensitivity. ,− Such structures include Bragg mirrors, , rugate filters, ,,− microcavities, ,,,,,− Thue–Morse structures, waveguides, , Vernier effect-based structures, Bloch surface wave structures, ring resonators, , and diffraction gratings . Weiss and co-workers extensively studied biosensors based on DNA-PNA hybridization with different PSi-based optical structures.…”