Figure 22. Applications of magnetic soft materials for programmable and reconfigurable surfaces.

Hard-magnetic micropillar arrays (a) transporting liquid droplets and (b) spreading liquids using magnetically controlled deformation of the pillars. (c) Hard-magnetic cilia transporting fluids through traveling metachronal waves under rotating magnetic fields. (d) Peristaltic pump based on microassembled hard-magnetic composites for transporting particles or liquids under rotating magnetic fields. (e) Hard-magnetic micropillar array with encrypted patterns that can be revealed under an applied magnetic field. (f) Hard-magnetic microplate array with each side of the plate colored differently to realize magnetically controlled active camouflage. (g) Hard-magnetic soft composite based on materials with low Curie point (e.g., CrO₂) and laser-assisted heating for spatially selective remagnetization (left). A magnetic soft composite surface encoded with a complex magnetization pattern through contact transfer of the magnetization profile from a magnetic master under global heating of the composite while in contact with the master surface (right). Panel (a) is reproduced with permission from ref 193 (Copyright 2018 Wiley); panel (b) from ref 198 (Copyright 2020 American Chemical Society); panel (c) from refs 158 and 330 (Copyrights 2020 American Association for the Advancement of Science and 2011 Cambridge University Press); panel (d) from ref 194 (Copyright 2021 American Association for the Advancement of Science); panel (e) from ref 198 (Copyright 2020 American Chemical Society); panel (f) from ref 199 (Copyright 2019 Wiley); and panel (g) from ref 215 (Copyright 2020 American Association for the Advancement of Science).