A Rapid and High-Throughput Assay for Light Scattering of SARS-CoV-2 Virion-Sized Particulates via Microfluidic Spray Device Reveals the Protection Performance of Face Masks against Virus Infection.

To prevent interhuman transmission of viruses, new mask types─claiming improved filtration─require careful performance characterization. Here, a microfluidic spray device that can effectively simulate droplets emitted during coughing or sneezing was developed to spray droplets containing gold nanoparticles (AuNPs) that mimic SARS-CoV-2 to overcome the shortcomings associated with using biosamples. The light scattered by the AuNPs passing through the mask is successfully analyzed by using an automated scattering light mapping system within a duration of 2 min, thereby enabling high-throughput analysis of the filtering efficiency of various types of commercial masks. The differences in efficiency in terms of same mask type from different manufacturers, double masking, and prolonged usage, which are challenging to analyze with conventional testing systems, can also be assessed. AuNP-mediated mask performance evaluation enables the rapid determination of mask efficiency according to particle size and can contribute to the rapid response to counter new emerging infectious biohazards.