Figure 21. Applications of magnetic soft materials for magnetically reconfigurable active origami and metamaterials.

(a) Rigid panels with patterned nanomagnet arrays connected by microfabricated hinges morphing into a microscopic crane upon the application of an external magnetic field. (b) Miura-ori fold made of a hard-magnetic soft composite encoded with alternating oblique patterns of magnetic polarities. Auxetic structures with negative Poisson’s ratios based on 3D-printed (c) hard-magnetic (torque-driven) and (d) soft-magnetic (force-driven) composites exhibiting shrinkage in both length and width under applied magnetic fields. (e) Torque-driven auxetic behavior of a manually assembled structure based on embedded magnets connected by flexible members. (f) Tensegrity structure based on injection-molded soft-magnetic soft composites exhibiting force-driven auxetic behavior under an applied magnetic field. (g) 2D lattice structure based on manually assembled hard-magnetic composites connected by asymmetrically bendable joints exhibiting different torque-driven auxetic behavior depending on the applied field direction for magnetically tunable acoustic properties. (h) 3D-printed 2D lattice structure based on hard-magnetic elastomer and shape memory polymer exhibiting temperature-dependent torque-driven auxetic behavior. Panel (a) is reproduced with permission from refs 80 and 20 (Copyright 2019 Springer Nature); panels (b) and (c) from ref 156 (Copyright 2018 Springer Nature); panel (d) from ref 173 (Copyright 2019 Wiley); panel (e) from ref 212 (Copyright 2019 American Association for the Advancement of Science); panel (f) from ref 162 (Copyright 2020 American Association for the Advancement of Science); panel (g) from ref 324 (Copyright 2021 Wiley); and panel (h) from ref 110 (Copyright 2021 American Chemical Society).