3D embedded printing of microfluidic devices using a functional silicone composite support bath

Over the last two decades, microfluidic devices have rapidly emerged as revolutionary platforms for research and medicine. Various kinds of materials and fabrication strategies have been used to manufacture microfluidic devices; however, most of these strategies face challenges including complexity, time consumption, and cost in recreating delicate and intricate structural organizations. Herein, a silicone composite (Si-Co) was developed and employed as a functional support bath in which a sacrificial ink was 3D printed using embedded printing, enabling freeform fabrication of complex-shaped microfluidic devices. Si-Co was a soft material that had high optical transparency and tunable mechanical properties and yield stress with self-recovering ability. Sacrificial ink filaments formed inside the Si-Co support bath were found to be stable and circular with a wide range of resolution reaching up to 50 µm in channel size. The strategy was exemplified by fabricating microfluidic devices for generation of stable microgels of various sizes. To confirm biocompatibility of Si-Co, induced-pluripotent stem cell-derived endothelial cells were lined up inside microfluidic channels to obtain vascular mimics. Additionally, proof-of-concept spheroid fabrication devices were generated. Overall, the presented strategy allows for facile, rapid, cost-effective, and high-resolution printing and presents potential for the development of microfluidic devices for various applications, such as but not limited to organ-on-a-chip devices, 3D bioprinting and drug testing.