Figure 8.

Up: schematic representation of “printability” and “shape fidelity” or “shape retention” concepts. Middle: summary of some desirable rheological properties of BI and BMI based on three 3DBP techniques (extrusion-based, laser-based and droplet-based). High viscosities are acceptable for extrusion-based techniques, although it is necessary to bear in mind that excessive viscosity could hinder cellular viability. Droplet bioprinting or laser-based techniques require low viscosity, though minimal values are needed to prevent cellular sedimentation. Down: qualitative and semi-quantitative tests used to evaluate printability and shape retention: (A) filament collapse test; (B) filament fusion test. Photographs for filament collapse and filament fusion tests were adapted with permission from [70], Elsevier, 2021.