Ultra-rapid and low-cost fabrication of centrifugal microfluidic platforms with active mechanical valves

Abstract

Onsite fabrication of centrifugal microfluidic cartridges is one way to provide laboratory and diagnostics platforms for extreme point-of-care (EPOC) settings. This paper presents a rapid fabrication process of centrifugal microfluidic cartridges (discs) using only a cutter plotter that is as low-cost, portable and rapid as conventional printers. Moreover, we devised an active valving mechanism to enable the development of complex sequential fluidic processes. The valves are engraved during disc manufacture itself by the cutter plotter. These embedded valves prevent the need for additional fabrication equipment and materials for the inserts that are usually required for other active valves. The valves are actuated by an external mechanical force, and are called active mechanical valves (M-valve). The M-valve is robust over a wide range of spinning speeds (e.g. up to 7000 rpm or 2470 rcf) and can be actuated manually, or automatically by a robotic arm. To demonstrate our approach, we developed two fluidic systems for immunoassay and chromatography. The first microfluidic platform was developed to automate a fluidic protocol usually required for immunoassays from whole blood. In this microfluidic disc, non-biological liquids were used to demonstrate the application of M-valves for robust control over retention and release of reagents. The chromatography microfluidic cartridge is a miniaturized experimental system for testing the capability of a modified resin (Sepharose 6B-PEG5000) for the isolation of monoPEGylated ribonuclease (RNase). The fabrication of microfluidic discs and M-valves by a simple cutter plotter is the fastest and least expensive method for the onsite development and onsite manufacturing of diagnostic kits for research and actual use even in EPOC settings.