Combination of a centrifugal microfluidic device with a solution-loading cartridge for fully automatic molecular diagnostics

We present a centrifugal microfluidic device which is combined with a solution-loading cartridge for fully automatic molecular diagnostics of foodborne pathogens. The proposed device could perform all processes of molecular diagnostics including bead-based DNA extraction, isothermal DNA amplification and colorimetric amplicon detection. In particular, the 3D-printed solution-loading cartridge was incorporated into the device to enhance the sample handling capacity and eliminate laborious steps such as pipetting for sample loading and sealing the top of the device. The cartridge could store four kinds of essential solutions (a sample solution, a washing solution, an elution solution, and a loop-mediated isothermal amplification (LAMP) cocktail) for pathogen detection, and the designated solutions were automatically released into the microdevice in a consecutive order by rotation. Since one unit of a device contains 20 reaction chambers, 18 kinds of pathogens plus two controls can be simultaneously detected in one test. As a proof-of-concept, we targeted four kinds of foodborne pathogens (Escherichia coli O157:H7, Salmonella typhimurium, Vibrio parahaemolyticus and Listeria monocytogenes) and successfully verified them, demonstrating that the centrifugal microdevice could be combined with a 3D printed solution-loading cartridge to achieve fully automated lab-on-a-chip-based molecular diagnostics. The entire process was completed in 65 min, and the limit of detection of the assay was 100 bacterial cells. The employment of the solution-loading cartridge successfully replaced the laborious and error-prone manual loading processes, which realized true automation of molecular diagnostics. This device could have promise in the fields of lab-on-a-chip and point-of-care molecular diagnostics.