A 3D Microfluidic-Based Hydrogel Microcapsule Fabrication System

To meet the demand for hydrogel microcapsule fabrication, this study aimed to develop a high-throughput system based on a 3D microfluidic chip for producing core-shell microcapsules. The system uses 3D micro-/nano- printing technology, which offers fast prototyping, low cost, and high precision. This method enables precise control over the structure of the microcapsules. The system includes a droplet microfluidic chip with 3D microstructures, which are fabricated using a dual-layer sheath flow strategy to generate the microcapsules. Experimental results show that the flow-focusing region on the inner bottom surface of the 3D micro-/nano-printed mold has a flatness of 4.65 μm, and the dimensional errors in the three-phase channels are always less than 2 μm. Similarly, the PDMS plate holding the microchannels shows a flatness of 4.81 μm. The channel dimensional errors in the PDMS plate are also within 2 μm. These results indicate that both the mold and the PDMS plate possess high flatness and accuracy, meeting the technical requirements for making microcapsules. Microcapsules with different inner diameters were prepared by changing the flow rate of the core solution (40, 60, 80, 100, 120 μL/h), while the outer diameter remained nearly constant. The microcapsules produced by the system have a very low coefficient of variation (CV<3%) for both outer and inner diameters, showing that the capsules are very uniform in size. Finally, cell culture tests were done to evaluate the biocompatibility and functionality of the microcapsules. A549 cells showed clear growth and clustering after two days of culture inside the microcapsules, confirming that the microcapsules from this system support cell growth well. These results suggest that the system has great potential for large-scale applications in biomedical fields.