Abstract: The present invention relates to a process for detecting a virus that include the steps of: taking a biosample (e.g. saliva) suspected of containing a virus, mixing it with a solution comprising nanoparticles having easily detectable properties (e.g. a color) and also comprising contrasting microparticles (e.g. clear or white), each having attached chemical compounds (e.g. antibodies) that selectively bind to the virus to be detected (e.g. SARS-CoV-2). When suitably mixed together, virus present in the biosample may bind to the nanoparticles and to the microparticles, connecting the two. When the mixture is then passed through a microfluidic assembly with dimensions that trap the microparticles but pass unbound nanoparticles, the detection of the presence of nanoparticles bound to the microparticles at the microfluidic filter indicates the presence of the virus to be detected. The process may include a concentration step to accelerate binding the virus to the nano- and micro-particles.