title: Combinatorial design of textured mechanical metamaterials.
abstract: The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks-voxels-that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.
authors.affiliation: Huygens-Kamerlingh Onnes Laboratory, Universiteit Leiden, PO box 9504, 2300 RA Leiden, The Netherlands.|FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Corentin
authors.initials: C
authors.lastname: Coulais
authors.affiliation: School of Mechanical Engineering and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Eial
authors.initials: E
authors.lastname: Teomy
authors.affiliation: Huygens-Kamerlingh Onnes Laboratory, Universiteit Leiden, PO box 9504, 2300 RA Leiden, The Netherlands.
authors.forename: Koen
authors.initials: K
authors.lastname: de Reus
authors.affiliation: School of Mechanical Engineering and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Yair
authors.initials: Y
authors.lastname: Shokef
authors.affiliation: Huygens-Kamerlingh Onnes Laboratory, Universiteit Leiden, PO box 9504, 2300 RA Leiden, The Netherlands.|FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: van Hecke
mesh_terms: D006696:Holography; D019563:Mechanics; D066330:Printing, Three-Dimensional; D019736:Prostheses and Implants; D012371:Robotics / Q000295:instrumentation; D013499:Surface Properties