Hydrogel Scaffold Printing Assisted by Substrate Cooling and an Electric Field

Lateral spreading and deformation during layer stacking limit the geometric fidelity of extrusion-printed hydrogel scaffolds. To address these constraints, this study presents an extrusion-printing strategy that combines electrical assistance and substrate cooling for poly(vinyl alcohol)/gelatin methacryloyl/alginate hydrogels. Electrical assistance improved filament uniformity in the simulations and independent controls, while separate cooling controls showed better preservation of lattice openings. The process produced filaments approximately 152 μm wide, and connected patterns retained distinct corners, curved boundaries and junctions. Three independently printed grids yielded a square-pore printability index of 0.9256 ± 0.0034. Three ten-layer specimens also retained open pores and reached a mean height of approximately 1.40 mm. After printing, ultraviolet irradiation and three freeze-thaw cycles stabilized the constructs. Compression tests on cast hydrogel specimens showed increasing resistance to deformation with additional freeze-thaw cycles. Curved patterns, structures of different heights and a meniscus-shaped construct further demonstrated the range of printable geometries. Together, these results support the strategy for fine filament deposition and open multilayer construction in this hydrogel blend.