Evaluating Flow‐Focused Microfluidic Device Fabrication Techniques for Silk Fibroin Microgel Production

ABSTRACT Silk microgels are promising biomaterials due to their tunable morphological and mechanical properties, and ability to form 3D scaffolds with micro‐pores, offering significant advantages over traditional nanoporous bulk hydrogels. This study compares three microfluidic fabrication techniques (maskless photolithography, laser engraving, and 3D printing) for generating silk fibroin microgels photo‐crosslinked via visible light to form covalent dityrosine bonds between native tyrosines in silk. Microfluidic devices with channel depths of 50, 100, or 400 µm are successfully fabricated using the three techniques, each offering distinct advantages and limitations in terms of precision, cost, and availability. The size of microgels (50–400 µm) is controlled by adjusting the channel depth and flow rate ratio, while the microgel shape is regulated by modifying the crosslinking location. Silk degumming time is adjusted to control silk molecular weight with lower molecular weight silk resulting in higher porosity and softer microgels while maintaining consistent microgel size. Silk microgels supported cell adhesion, spreading, and proliferation, demonstrating their potential for use in cell expansion and tissue engineering applications. This work highlights the versatility of microfluidic fabrication strategies for tailoring the properties of silk microgels, offering a natural polymer biomaterial platform for biomedical and tissue engineering applications.