Development of an opto-fluidic 3D bio-printer for high resolution and multimaterial printing of hydrogel ; Développement d’une bio-imprimante 3D opto-fluidique pour l’impression haute résolution et multimatériaux d’hydrogel

Here, we introduce a pioneering concept in 3D printing applied to biological applications. The 3D-FlowPrint platform has been devised to execute high-resolution prints using multiple materials. The 3D-FlowPrint platform employs a microfluidic system to channel fluids to a submerged printhead, where the injected solution undergoes photopolymerization. By decoupling material deposition from polymerization, this platform attains both high resolution and the versatility to work with diverse materials.The heart of this platform resides in the design of its printhead. This printhead enables fluid injection and retrieval without environmental contamination, while facilitating laser transmission through an integrated optical fiber. To achieve these goals, we have combined 3D printing with optically compatible material assembling. It enabled reproducible hydrogel prints to develop and characterize the platform.The printheads operate immersed, enabling printing in cultured environments. These heads include an injection channel and an aspiration channel, along with surface reliefs ensuring complete collection of the injected solution to minimize contamination. Utilizing finite element-based numerical simulations, phase diagrams have been established to evaluate the work conditions. These simulations guided the optimization of surface reliefs to enhance the performance of the printheads. Additionally, the ability to transition from one fluid to another in multi-material printing was analyzed.The introduction of an optical fiber between the microfluidic channels allowed the photopolymerization of the injected solution. The platform gained versatility with dual printing speeds enabled by the insertion of two optical fibers in the 3D printed printheads. Photopolymerization thresholds of PEGDA and GelMA were investigated, and the impact of in-flow photopolymerization was verified. These analyses culminated in the printing of 2D, 2.5D, 3D, and multi-material structures with reproducible precision down to 7 micrometers.Serving as ...