Figure 31.

(a) An emerging mechanism for active metamaterials is magnetism: a novel DIW approach is used to tune the magnetic pole orientation of different regions during printing that leads to intricate deformations that can be well predicted; (b) metamaterials that use an asymmetricfolding joint can achieve drastically different configurations under opposite magnetic fields; (c) a DIW-printed metamaterial that floats on water harnesses magnetic and capillary forces to achieve interesting deformations; (d) an SLA-printed hollow lattice is filled with a magnetic ink that can be used to adjust the lattice stiffness under a magnetic field; (e) a 3D-printed scaffold allows for the injection of a magnetic ink followed by the dissolution of the scaffold. Applying a magnetic field changes the acoustic absorption properties [149].