A pocket-sized device automates multiplexed point-of-care RNA testing for rapid screening of infectious pathogens

Abstract Rapid screening of infectious pathogens at the point-of-care (POC) is ideally low-cost, portable, easy to use, and capable of multiplex detection with high sensitivity. However, satisfying all these features in a single device without compromise remains a challenging task. Here, we introduce an ultraportable, automated RNA amplification testing device that allows rapid screening of infectious pathogens from clinical samples. In this device, 3D-printed structural parts incorporated with off-the-shelf mechanic/electronic components are utilized to create an inexpensive and automated droplet manipulation platform. On this platform, a simple configuration that couples a linear displacement of the chip with a tunable magnet array allows parallel and versatile droplet operations, including mixing, splitting, transporting, and merging. By exploiting a multi-channel droplet array chip to preload necessary reagents in "water-in-oil" format, bacteria lysis, RNA extraction and amplification are seamlessly integrated and implemented by the combination of droplet operations. Furthermore, visual readout and geometrically-multiplexed quantitative detection are provided by an integrated wireless video camera-enabled wide-field fluorescence imaging. We demonstrated that this droplet-based device could have a shorter RNA extraction time (12 min) and lower detection limits for pathogenic RNA (approaching to 102 copies per reaction). We also verified its clinical applicability for the rapid screening of four sexually transmitted pathogens from urine specimens. Results show that the sample-to-answer assay could be completed in approximately 42 min, with 100% concordance with the laboratory-based molecular testing. The exhibiting features may render this microdevice an easily accessible POC molecular diagnostic platform for infectious disease, especially in resource-limited settings.