High-resolution low-cost LCD 3D printing of microfluidics

The fabrication of microfluidic devices has progressed from cleanroom manufacturing to replica molding in polymers, and more recently to direct manufacturing by subtractive (e.g., laser machining) and additive (e.g., 3D printing) techniques, notably digital light processing (DLP) photopolymerization. However, many methods require technical expertise and while DLP 3D printers remain expensive at a cost [~]15-30K USD with [~]8M pixels that are 25-40 {micro}m in size. Here, we introduce (i) the use of low-cost ([~]150-600 USD) liquid crystal display (LCD) photopolymerization 3D printing with [~]8M-58M pixels that are 18-35 {micro}m in size for direct microfluidic device fabrication and (ii) a poly(ethylene glycol) diacrylate-based ink developed for LCD 3D printing (PLInk). We optimized PLInk for high resolution, fast 3D printing and biocompatibility while considering the illumination inhomogeneity and low power density of LCD 3D printers. We made lateral features as small as 75 {micro}m, 22-{micro}m-thick embedded membranes, and circular channels with a 110 {micro}m radius. We 3D printed microfluidic devices previously manufactured by other methods, including an embedded 3D micromixer, a membrane microvalve, and an autonomous capillaric circuit (CC) deployed for interferon-{gamma} detection with excellent performance (limit of detection: 12 pg mL-1, CV: 6.8%), and we demonstrated compatibility with cell culture. Finally, large area manufacturing was illustrated by printing 42 CCs with embedded microchannels in <45 min. LCD 3D printing together with tailored inks pave the way for democratizing access to high-resolution manufacturing of ready-to-use microfluidic devices by anyone, anywhere.