A CRISPR-assisted passive microfluidic chip for rapid, visual detection of multiple respiratory viruses

In recent years, viral co-infections, particularly with respiratory viruses, have resulted in more complex symptoms, a greater disease burden, and increased challenges in clinical decision-making. These complexities underscore the urgent need for improved diagnostic tools in the managing acute respiratory infections. To address the limitations of conventional qPCR and current POCT methodologies, we developed a passively driven microfluidic chip capable of rapidly screening multiple respiratory viruses. This platform is particularly suited for the point-of-care diagnosis of viral co-infections. Our device integrates nucleic acid amplification and CRISPR-based detection within a single, passively operated system. By utilizing a rapid, 10-minute sample preparation protocol and a 35-minute on-chip assay, this platform enables the multiplex detection of influenza A/B, human parainfluenza virus, and SARS-CoV-2. The total assay time from sample to answer is approximately 45 min, with equipment requirements minimized to a heating block. The assay demonstrated a detection sensitivity of about 10 copies/µL for viral RNA in dilution series experiments. The sensitivity of the assay was 98.44% (95% CI: 91.6%-99.96%), and the specificity was 100% (95% CI: 79.4%-100%). The system combines CRISPR-Cas12a-mediated sensing with reverse transcription recombinase polymerase amplification (RPA) for highly specific nucleic acid detection. The chip design utilizes capillary action and gravity-driven flow for autonomous fluid control, while lyophilized reagent preloading ensures storage stability and minimizes user intervention.