Microfluidic-based biosensor for SARS-CoV-2 antibodies

This chapter addresses the basis for designing, prototyping, and developing a biosensing platform to support the control of the current global pandemic caused by the COVID-19 disease using an acoustic-based biosensor able to detect and quantify the IgM-and-IgG-specific antibodies against the spike protein (S) receptor-binding domain (RBD) from the SARS-CoV-2 virus, analyzing patient serum samples. The antibody detection technique is a well-known indicator if the patient has been in contact with the virus and is considered the only valid test in asymptomatic patients. This chapter includes a description of required actuators, fluidics, and electronics to perform an automatic immunoassay. The established measurement format for the present biodetection platform was a direct immunoassay, using IgM/IgG antibodies in a serological sample, which comes in contact with the spike RBD domain immobilized on a Quartz Crystal Microbalance (QCM) surface. The biodetection platform can detect and quantify IgM+IgG antibodies in a concentration of 2.53 μg L−1 and 17.88 μg L−1, respectively. Moreover, the calculated sensitivity (I50) was 27.69 μg L−1. The aforementioned analytical parameters are comparable with reports in which a QCM acoustic transducer was employed as an immunosensor for biosensing applications.