Coaxial Bioprinter Design & Validation

Abstract

Vasculatures are key components to life, enabling transport of critical life-sustaining fluids, like blood in humans, or water in trees. To make artificial structures that exhibit characteristics of life, it is important to mimic nature and enable vascularization for human-made materials. The technology to print vascular materials exists, but there are major challenges regarding how to integrate these materials, and their industrial scalability. This thesis investigates coaxial bioprinting as a scalable option and details the design, development, and validation of a coaxial extrusion-based bioprinter engineered for the fabrication of perfusable calcium alginate vascular structures. The outcome of the design process was a new coaxial nozzle capable of printing controlled and consistent vascularized alginate structures directly onto a print bed. This is a key step enabling scalable vasculature manufacturing as the use of printing baths and gels is completely avoided. The printers capabilities were then validated and found to meet the initial design specifications. Further, the accuracy of printing planar features was quantified followed by demonstrations of fully perfusable 3D prints. Results show that the vasculature’s inner channel size can be controllably tuned by varying the nozzle size combinations, enabled by the new nozzle design. In addition, the geometry of the extrusion can be controllably tuned while printing by varying the extrusion factor. Experiments showed that the printer can handle printing sharp angles with an error of up to 10 degrees, which enables complex vascularized shapes. Additionally, curves were shown to be printed accurately at radius of half of that of the diameter of the vasculature and larger. Bridging testing resulted in a optimal setting of extrusion factor to bridge 25mm gaps at a height of 5mm. The final design fulfils all predefined functional and performance requirements, confirming the feasibility of modular coaxial bioprinting for vascular fabrication. The resulting platform provides a truly cost-effective and scalable foundation for manufacturing man-made vascularized structures.