Ferrowax microvalve-utilized centrifugal microfluidic system for a fully automated serial dilution

Abstract

We herein describe an ingenious centrifugal microfluidic system to\naccomplish a fully automated serial dilution. The liquid flow on the\ndisc was automatically regulated by utilizing ferrowax microvalves\nsystematically integrated into the channels within the specially\ndesigned metering structure. By opening the differently positioned\nmicrovalves through irradiation of IR laser to allow metering, the same\namount of diluent was serially eluted to the dilution chamber from the\nsame diluent chamber. After dilution, the diluted samples were\nautomatically delivered to the respective final product chambers by\nappropriately opening or closing the microvalves in the connecting\nchannels, followed by rotating the disc. Based on this unique design\nprinciple, six consecutive two-fold and ten-fold dilutions were\nsuccessfully achieved, yielding excellent accuracy in a wide dynamic\nrange up to six orders of magnitude. Very importantly, the overall\nserial dilution process, including the diluent addition, mixing, and\nproduct transfer steps, was completed very rapidly within five minutes,\ndue to the minimized procedures enabled by the automated actuation of\nthe ferrowax microvalves at the rationally designed positions. The\ncentrifugal microfluidic system would serve as a powerful elemental tool\nto realize the fully automated diagnostic microsystem involving the\nserial dilution process.