Portable wide-field femtoliter-chamber imaging system for point-of-care digital bioanalysis

Recently, digital bioanalysis using femtoliter (fL)-chamber arrays has significantly improved the sensitivity, accuracy, and throughput of conventional nucleic acid and antigen tests, with great potential for the diagnosis of infectious diseases and underlying disorders. However, the large size of conventional platforms with costly assay consumables for digital bioanalysis complicates its use in point-of-care testing (POCT). To solve these problems, in this study, we developed a wide-field fL-chamber imaging system (COWFISH2), a portable wide-field femtoliter-chamber imaging system (footprint: 14 × 22 cm), by redesigning various electronic controls and optical systems of COWFISH, accompanied by the development of low-cost and durable consumables for digital bioanalysis. As a proof of concept, the point-of-care digital bioanalysis was successfully performed in a hospital setting, using amplification-free multiplex digital RNA detection of SARS-CoV-2, influenza A virus, and influenza B virus. Collectively, COWFISH2 will facilitate versatile and convenient digital bioanalysis in POCT, contributing to the improvement of public health, including the prevention of infectious diseases.