Design and fabrication of a low-cost microfluidic cartridge with integrated pressure-driven check valve for molecular diagnostics platforms

Abstract

This paper describes the design, fabrication, and preliminary testing of a low-cost, easy to manufacture microfluidics cartridge capable of fluid storage and manipulation through a custom pressure-driven check valve. Cartridge components are fabricated using a desktop CNC and laser cutter, the check valve is fabricated using PDMS in a custom acrylic mold, and the components are assembled using a thermal diffusion welder. Following assembly, preliminary testing of the cartridge, including fluid manipulation and use for molecular diagnostics, was performed. To pull a sample into the lysing chamber, a vacuum over 1.4PSI was required. No opening of the valve to the reaction chamber was observed. Moving fluid across the custom valve from the lysing chamber to the reaction chamber then required a vacuum over 4.5PSI. Finally, a proof-of-concept demonstration of one potential application was performed using a custom benchtop LAMP system for molecular diagnostic testing. The low-cost nature of the design, ease of manufacturing, fluid storage and manipulation demonstrated make this design ideal for research and high-volume testing in low resource environments. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=72 SRC="FIGDIR/small/522222v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@13ebeb5org.highwire.dtl.DTLVardef@5a8ffaorg.highwire.dtl.DTLVardef@1a27cd5org.highwire.dtl.DTLVardef@b1bc2e_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstractCustom cartridge is fabricated using a combination of a) benchtop laser cutter and b) benchtop micromilling machine. c) Components are then assembled with a 0.22{micro}m micron filter and custom plug-style check valve. d) The cartridge assembly is then bonded using a thermal diffusion bonder. e) By pulling a vacuum through the first air trap, a sample can be pulled into the pre-filled lysing chamber. f) Pulling a vacuum through the second air trap, the lysed sample can then be pulled into the pre-filled reaction chamber. g) For a proof of concept, the filled cartridge was then tested in a custom benchtop Loop Mediated Isothermal System. Following a heating cycle, reaction fluoresce can be monitored. h) An S-Curve observed through the custom LAMP system, thus demonstrating feasibility of the cartridge for use with molecular diagnostic platforms.