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Although broadly admired for its aesthetic qualities, the art of origami is now being recognized also as a framework for mechanical metamaterial design. Working with the Miura-ori tessellation, we find that each unit cell of this crease pattern is mechanically bistable, and by switching between states, the compressive modulus of the overall structure can be rationally and reversibly tuned. By virtue of their interactions, these mechanically stable lattice defects also lead to emergent crystallographic structures such as vacancies, dislocations, and grain boundaries. Each of these structures comes from an arrangement of reversible folds, highlighting a connection between mechanical metamaterials and programmable matter. Given origami's scale-free geometric character, this framework for metamaterial design can be directly transferred to milli-, micro-, and nanometer-size systems. [ABSTRACT FROM AUTHOR]

The article discusses the design of responsive buckled surfaces by halftone gel lithography. The authors note the various applications of self-actuating materials that are capable of transforming between three-dimensional (3D) shapes, such as biomedicine, robotics, and tunable micro-optics. Topics include a method that uses copolymers that allow crosslinking for photopatterning polymer films capable of yielding temperature-responsive gel sheets that can transform between a flat state and a prescribed 3D shape and a method for the fabrication of surfaces with constant Gaussian curvature or zero mean curvature via halftone gel lithography using only two photomasks.