Open-source 3D printed air-jet for generating monodispersed alginate microhydrogels

Open-source designs represent an attractive and new tool for research as it provides both affordable and accessible options to the lab environment. In particular, with the advent of new and cheap additive manufacturing technologies, the open-source design of lab hardware enables others to perform research that would be difficult otherwise. This manuscript describes an air-jet system designed to be open-source and simple to produce with 3D printing. The fully 3D printed air-jet was designed for the generation of hydrogel microbeads of a controllable size. Alginate microbeads were used as a working model, given that it has many promising research applications due to their injectability and highly reproducible properties. A fit definitive design of experiments was performed to determine critical factors affecting diameter, index of dispersity, and circularity of microbeads from this air-jet design. By regulating alginate concentration, air pressure, pump speed, and needle diameter could achieve control over microbeads size from 200-800 {micro}m with low variance. Furthermore, we also demonstrate the potential probiotic research applications of the open-source air-jet through the encapsulation of bacteria in alginate microbeads with controllable degradation. The results of this study exhibit an open-source platform for making microscale biomaterials with controllable properties that can be achieved through budget 3D printers.