We are developing a rapid screening test that can detect the presence and concentration of SARS-CoV-2 in a patient’s saliva. This test is designed to meet the World Health Organization ASSURED criteria for on-site diagnostics (Affordable, Sensitive and Specific, User-friendly, Rapid/Robust, Equipment-free, and Deployable). The assay uses two types of microbeads to label the analyte: buoyant microbubbles and magnetic microspheres. Each bead is functionalized with antibodies that specifically target and bind to the SARS-CoV-2 nucleocapsid protein present in a patient’s saliva, forming buoyant-analyte-magnetic (BAM) complexes. These BAM complexes can be seen by the naked eye when illuminated with a flashlight. A simple setup, consisting of a magnet, camera, and flashlight video records the movement of these BAM complexes through solution. MATLAB video analysis allows us to count individual BAM complexes and track their motion. Through particle tracking, our team was able to detect concentrations of nucleocapsid protein at 1 fg/mL in 10 µL of phosphate buffered saline. In the future, our team plans to apply this assay to human saliva. Overall, these results highlight the potential applications within on-site diagnostics fields, including mobile integrated healthcare settings.