Abstract
Microfluidic resistive pulse sensing (MRPS) was used to determine the size -distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on detecting nearly 30,000 single virions. However, the ultrastructure of SARS-CoV-2 is thoroughly described, but ensemble properties of SARS-CoV-2, e.g., its particle size distribution, are sparsely reported. According to the MRPS results, the size distribution of SARS-CoV-2 follows a log-normal function with a mean value of 85.1 nm, which corresponds to an approximate diameter of the viral envelope. This result also confirms the low number (< 50) of spike proteins on the surface of the virions.