Designing and Prototyping a 3D Printer for Multi-Extrusion of Thermo- and Photocurable Hydrogels: Enabling Affordable and Wider Access to Bioprinting

Abstract

3D bioprinting is an area expanding rapidly, allowing for the design of intricate structures using multiple materials, including living cells. This has enormous potential for applications in drug testing, regenerative medicine, and more recently with the surge of the alternative protein field, cell-based food products. Therefore, strategies to effectively implement 3D bioprinting approaches are highly desirable. However, the high cost of equipment is a significant limitation for implementing these approaches. In this work, we aim at designing and developing a low-cost 3D extrusion bioprinter that allows for a wider access to this technique while presenting an extensive range of features compatible with multiple biomaterials. Initially, a fused deposition modelling (FDM) desktop 3D printer (Ender 3-V2) was modified and the mainboard and electronics were reconfigured to host two printing nozzles in the printhead. The designed extrusion system presented a maximum output force of 320 N and featured a temperature control unit (in the range of 2-50^oC) and UV-LEDs. Furthermore, this prototype was compatible and fully controlled with open-access software. The printability of the prototype was subsequently evaluated, consisting on a Pr of 0.995, being comparable with commercial solutions. The printer accuracy and precision were also assessed by developing representative calibration models based on ISO guidelines at various temperatures, deposition rates, dispensing tips and printing parameters; presenting high precision and low dimensional errors. Finally, to demonstrate its compatibility with the bioprinting process, we also successfully bioprinted scaffolds containing L929 mouse fibroblasts, maintaining a 97% cell viability seven days after post-printing. This work presents a prototype that integrates a greater number of features and functionalities than other low-cost bioprinters, offering one of the best price-quality ratios. As a result, this technology has the potential to positively impact the field by improving accessibility for users and facilitating its further expansion.