Open-source CAD-CAM simulator of the extrusion-based bioprinting process

Extrusion-based Bioprinting (EBB) represents one of the most used Bioprinting technologies among researchers, thanks to its ease of use, wide variety of available materials, and affordable cost. Even though the technique has successfully been applied in bioprinting constructs for Tissue Engineering applications, there is still no consensus on which parameters have more influence of the accuracy of bioprinted scaffolds. Moreover, the literature lacks a rapid and robust method to consistently set the printing parameters before the actual printing phase, thus minimizing the trial-and-error process. In this context, we present a mathematical model for understanding the printability of a defined structure by depositing a given biomaterial ink through a specific EBB apparatus. The model takes into account different steps of the printing process, including extrusion, line formation and scaffold stabilization over time. The model was experimentally validated and implemented in an open-source software to guide the user in setting the correct printing parameters (i.e., printing speed, layer height and flow) based on scaffold dimensions, material properties (including rheological and mechanical ones) and printer set-up. To encourage the model use, we also propose a set of experiments to extract the relevant material properties for our model, and the software is available both as a stand-alone program (available at https://github.com/CentroEPiaggio/Rheology-GUI), as well as a webpage (available at https://www.prin-vision.it/printability-assessment).