Low-Cost Microfluidic Fluorescence-Based Assay for Screening Viral Diseases at the Point of Care

Point of care diagnostics were especially relevant during the COVID-19 pandemic when it was apparent that early detection of the highly infectious SARS-CoV-2 respiratory virus was necessary to contain outbreaks. For a disease such as COVID-19 which does not manifest symptoms until several days after a person has been infectious and spreading the virus, it is critical to detect the virus as early as possible for quarantining. This is particularly important in rural and underdeveloped areas where traditional laboratories and skilled healthcare workers may not be available. To address this issue, we designed a low-cost microfluidic device using plastic film and adhesive tape, to use in conjunction with an electronic fluorescence detecting device. The chip was demonstrated with patient saliva samples; 5 positive for COVID-19 and 8 negative for the virus. The electronic device successfully detected strong fluorescence distinction between positive and negative samples with a p-value of $5.52 \times 10^{-6}$ at room temperature. The study infers that these microfluidic chips can be used for high-throughput screening of patient samples by running the assay in the chip and analyzing them for endpoint fluorescence in the electronic device. Clinical Relevance- Patient saliva samples can be screened for viral disease at the point of care with statistically significant distinction between positive and negative samples. The samples can be processed externally on a hot plate and the reaction can be halted for later analysis with distinguishable results.