High-resolution low-cost LCD 3D printing for microfluidics and organ-on-a-chip devices.

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 DLP 3D printers remain expensive at a cost ∼15-30 K USD with ∼8 M pixels that are 25-40 µm in size. Here, we introduce (i) the use of low-cost (∼150-600 USD) liquid crystal display (LCD) photopolymerization 3D printing with ∼8-58 M pixels that are 18-35 µm 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 µm, 22 µm-thick embedded membranes, and circular channels with a 110 µm 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-γ detection with excellent performance (limit of detection: 12 pg mL-1, CV: 6.8%). We made PLInk-based organ-on-a-chip devices in 384-well plate format and produced 3420 individual devices within an 8 h print run. We used the devices to co-culture two spheroids separated by a vascular barrier over 5 days and observed endothelial sprouting, cellular reorganization, and migration. LCD 3D printing together with tailored inks pave the way for democratizing access to high-resolution manufacturing of ready-to-use microfluidic and organ-on-a-chip devices by anyone, anywhere.

High-Resolution Additive Manufacturing of a Biodegradable Elastomer with A Low-Cost LCD 3D Printer.

Artificial organs and organs-on-a-chip (OoC) are of great clinical and scientific interest and have recently been made by additive manufacturing, but depend on, and benefit from, biocompatible, biodegradable, and soft materials. Poly(octamethylene maleate (anhydride) citrate (POMaC) meets these criteria and has gained popularity, and as in principle, it can be photocured and is amenable to vat-photopolymerization (VP) 3D printing, but only low-resolution structures have been produced so far. Here, a VP-POMaC ink is introduced and 3D printing of 80 µm positive features and complex 3D structures is demonstrated using low-cost (≈US$300) liquid-crystal display (LCD) printers. The ink includes POMaC, a diluent and porogen additive to reduce viscosity within the range of VP, and a crosslinker to speed up reaction kinetics. The mechanical properties of the cured ink are tuned to match the elastic moduli of different tissues simply by varying the porogen concentration. The biocompatibility is assessed by cell culture which yielded 80% viability and the potential for tissue engineering illustrated with a 3D-printed gyroid seeded with cells. VP-POMaC and low-cost LCD printers make the additive manufacturing of high resolution, elastomeric, and biodegradable constructs widely accessible, paving the way for a myriad of applications in tissue engineering and 3D cell culture as demonstrated here, and possibly in OoC, implants, wearables, and soft robotics.