Robust and scalable production of emulsion-templated microparticles in 3D-printed milli-fluidic device

Emulsions are ideal templates for preparation of functional microparticles in food, cosmetics, and pharmaceutics. However, the lack of a simple and robust platform that allows mass production of oil-in-water (O/W) emulsions has been considered as a practical hurdle for broader applicability of these emulsion-based technologies. Herein, we report a novel 3D-printed milli-fluidic device (3D-PMD) for robust and scalable production of water-in-oil (W/O) as well as O/W emulsions. By using an additive manufacturing method with one-step prototyping capability, 3D-PMD integrates an array of 40 drop-makers with a 3D void geometry and a flow distributor in a compact fashion, which has been difficult to achieve using conventional methods. Experimental results as well as the computational fluid dynamics simulation confirm the validity in the design of the drop-maker and the flow distributor, as well as the hydrophilic surface modification process for the robust and controllable production of poly(ethylene glycol) microgels and polycaprolactone microparticles, prepared from W/O and O/W emulsions, respectively. We anticipate that the simplicity, low-cost ($150/per device), facile manufacturability, and versatile emulsion production capability of our 3D-PMD method offers a unique route to produce W/O and O/W emulsions in a robust and in a scalable manner, providing new and exciting opportunities in various applications involving functional microparticles such as cosmetic products, optical displays, controlled reactions, and drug delivery systems to name a few.