Figure 14.

4D bioprinting. (A) Schematic of a shear-induced alignment of cellulose fibrils during extrusion bioprinting and subsequent effects on anisotropic stiffness and swelling. (B, C) Photographs showing (B) bioprinted and (C) transformed structure of a flower demonstrating the morphology inspired by a native orchid, the Dendrobium helix. Reproduced with permission from ref.^[203]. (D) Schematics of a magnetically guided printing process and material composition. Ferromagnetic nanoparticles embedded in the composite ink were reoriented by an applied magnetic field generated by a permanent magnet or an electromagnet placed around the dispensing nozzle. (E) A reconfigurable soft electronic device based on an annular ring structure exhibiting different electronic functions depending on the direction of the applied magnetic field. (F) Hexapedal structure stopping and holding a fast-moving object (glass ball with diameter of 18 mm and weight of 8 g) upon application of a magnetic field generated by a permanent magnet. (G) A hexapedal structure wrapping an oblong pharmaceutical pill and carrying the pill using rolling-based locomotion under a rotating magnetic field generated by a permanent magnet. (H) Horizontal leap of a 3D auxetic structure upon sudden reversal of the applied magnetic field direction while attenuating the field strength by rotating a permanent magnet by 90°. Reproduced with permission from ref.^[204].