Design of a CMOS-compatible photonic crystal biosensor for SARS-CoV-2 detection [Invited]

This study presents the design and optimization of a one-dimensional photonic crystal (1D PhC) biosensor tailored for the detection of SARS-CoV-2 RNA, spike RBD glycoprotein, and monoclonal IgG. By leveraging Bloch surface waves (BSW) and defect mode engineering, the proposed sensor achieves exceptional optical confinement and sharp resonance features. A systematic parameter sweep including incident angle, defect layer thickness, and total number of periods demonstrated their profound influence on sensitivity, quality factor (QF), and figure of merit (FOM). Optimal performance was achieved at an incident angle of 88°, a defect thickness of 10 F , and N =8 periods, yielding a maximum sensitivity of 2280 nm/RIU with FOM values exceeding 1.1×10 4 RIU −1 . These metrics outperform many reported photonic biosensors and confirm the device’s capability for high resolution, label-free detection of refractive index (RI) changes in COVID-19 biomarkers. The proposed architecture, based on CMOS-compatible Si/MgF 2 materials, offers a scalable and cost effective platform for next-generation point-of-care diagnostics. Beyond SARS-CoV-2, the results establish a versatile framework for tailoring 1D PhC biosensors toward a wide range of viral and biomedical targets.