Figure 8.

Various light-based and extrusion-based printing techniques can be used for 3D printing. In combination with stimuli-responsive hydrogels as (bio)inks, the printed construct can undergo further dynamic changes, which can be spatiotemporally controlled by various on-demand triggers (e.g., hydration, biological, temperature, light, or electrostatic). The fabrication of biomaterials by means of 3D printing techniques combined with stimuli-responsive inks is referred to as 4D (bio)printing.