Figure 1.

Flow chart demonstrates the process of biomaterial ink evaluation through the definitions of precursor, weak hydrogel, true hydrogel, and biomaterial ink. (precursor → weak hydrogel → biomaterial ink → true hydrogel). Precursor, polymer solution or pre-hydrogel solution without crosslinking. Weak hydrogel, weakly crosslinked hydrogel (extrudable). Biomaterial ink, printable precursor (weak hydrogel) or precursor candidate for 3D bioprinting that has been screened for printability through various evaluation steps: precursor preparation, precrosslinking, prescreening for printability (filament formation and stackability), rheological analysis (degree of shear-thinning, yield stress, and recovery behavior), 3D printing (multilayer printing), and postcrosslinking (stabilization). True hydrogel, crosslinked hydrogels with mechanically stable to maintain the structural integrity after printing.³⁶