Quantitative Assessment of Hydrogel Printability in Extrusion Bioprinting

Extrusion-based 3D bioprinting enables the fabrication of complex tissue structures, yet achieving both high structural fidelity and cell viability remains challenging due to complex bioink rheology and parameter interplay. This review presents a quantitative framework linking hydrogel properties to printing outcomes. Key rheological features-shear-thinning, yield stress, reversible gel-sol transition, self-healing, and creep resistance-are examined for their roles in extrusion and shape retention. We also evaluate printing accuracy using metrics such as filament uniformity and multilayer stability. Advanced models, including Herschel-Bulkley and extrusion pressure models, correlate material parameters with flow dynamics and predict critical factors like wall shear stress. Finally, we propose an integrated assessment system combining material properties, process parameters, and structural fidelity to guide bioink design and printing optimization, advancing the field of hydrogel bioprinting.