A self-reference multi-channel optical fiber microcavity biosensor for SARS-CoV-2 detection

The false-positive problem in biosensing significantly compromises detection accuracy. Herein, we present a multi-channel optical fiber microcavity biosensor designed to suppress false-positive responses, which is demonstrated through the quantitative detection and analysis of SARS-CoV-2. The fabrication of sensor accomplished by encapsulating optical fiber Fabry-Perot (FP) interferometer, followed by antibody functionalization. This approach enables the quantitative and specific detection of SARS-CoV-2 through real-time monitoring the interference spectrum wavelength shift. The sensor was designed with three detection channels (experimental, parallel, and control) for the simultaneous detection of SARS-CoV-2. The parallel channel was used to validate the detection accuracy of experimental channel, while the control channel was employed to identify and eliminate false positives caused by non-specific adsorption, which enabled the self-referencing function of the sensor. The experimental results demonstrated that the sensor exhibited a linear sensitivity of 0.493 nm/(μg/mL) for the SARS-CoV-2 recombinant protein antigen, with a detection limit of 32.4 ng/mL and good specificity. Both the parallel and control channels confirmed the sensor's reliability: the former verified detection accuracy by showing comparable results, and the latter enabled the elimination of false positives by providing a correction baseline for non-specific binding.