High-Resolution Heterogeneous Hydrogel Printing Using a Home Projector.

Soft hydrogels are being increasingly recognized for their versatility and unique properties, making them attractive for a range of applications in tissue engineering, biomedical devices, and beyond. Among fabrication methods, 3D printing stands out for its precise control over material distribution, enabling the creation of complex structures. Traditional printing methods, however, struggle to produce heterogeneous hydrogels with diverse properties. Here, a novel approach is introduced utilizing polyvinyl alcohol bearing styrylpyridinium groups (PVA-SbQ) for high-resolution heterogeneous hydrogel printing. By leveraging the photoreactive nature of PVA-SbQ, precise control over crosslinking time at different positions within a PVA-SbQ hydrogel is demonstrated using a simple home projector. This enables the creation of intricate patterns with tailored properties within a heterogeneous hydrogel, showcasing synergistic combinations of soft and tough domains, as well as high and low swelling regions. The method not only advances the field of hydrogel printing but also holds promise for applications in pattern encryption, 4D printing, cell organization, and cell alignment. By overcoming the limitations of traditional printing techniques, the approach opens new avenues for the fabrication of complex and heterogeneous hydrogel structures with diverse applications in biomedical engineering and beyond.