18, 19 Additionally, microvalves allow for tuning of flow resistance 20 and microchannel topography 21 (among other operations) at a spatiotemporal scale that is inaccessible to manual manipulation. 1– 8 Using microvalves, temporal sequences of fluids can be programmed to produce combinatorial mixtures and gradients, 9– 13 droplet combinations, 14 nucleic acid manipulations, 15– 17 and cell culture conditions. Microvalves and micropumps are fundamental components of many microfluidic systems. Overall, we demonstrate the 3D-printing of compact microvalves and micropumps using a process that precludes the need for specialized, time-consuming labor. valves to demonstrate the reliability and scalability of the valves. Moreover, we printed a 64-valve array constructed with 500 μm-diam. The micropump only requires positive pressure for its operation and profits from the fast return to the valves’ open states. We also 3D-printed a micropump by combining three Quake-style valves in series. Although the flexibility of PEG-DA-258 is inferior to that of other microvalve fabrication materials such as PDMS, the valve benefits from the bowl design and the membrane’s high restoring force since it does not need a negative pressure to re-open.
We used poly(ethylene diacrylate) (MW = 258) (PEG-DA-258) as the resin because it yields transparent cytocompatible prints. We used a stereolithographic (SL) 3D printer to print a thin (25 or 10 μm-thick) membrane (1200 or 500 μm-diam.) that is pneumatically pressed (~3–6 psi) over a bowl-shaped seat to close the valve. The open-at-rest valve design is derived from Quake’s PDMS valve design. Here we demonstrate a 3D-printable microvalve that is transparent, built with a biocompatible resin, and has a simple architecture that can be easily scaled up into large arrays.
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