Enhanced Detectability of SARS-CoV-2 Using Sandwich Immunoassay Sensor Based on Tilted Fiber Bragg Grating With Strong Cladding Mode Resonances

This research introduces a method for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizing tilted fiber Bragg grating (TFBG) with strong cladding mode resonances (~30 dB). The biofunctionalization treatment involves a series of surface biofunctionalizations, including the incorporation of an enhancer layer with avidin-biotin complex (ABC) to enhance the output response of the biosensor. The parameters studied include cutoff intensity change and wavelength shift of the lower envelope of the transmission spectra. For cutoff intensity change, the sensitivity of the biosensor improves by ~39.96%, and the limit of detection (LOD) decreases by ~56.94%. For wavelength shift, the sensitivity increases by ~48.96%, while the LOD is reduced by ~64.26%. Specificity tests, including those with non-SARS-CoV-2 samples, have been carried out to showcase the strong performance of the biosensor. In addition, control tests have been conducted to validate the biosensor’s reliability.