Mechanical and Civil Engineering Seminar

Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life.  Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly.  We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon.  The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling.  Designs inspired by kirigami/origami enable the formation of mesostructures with a broad variety of 3D geometries, either with hollow or dense distributions.  Demonstrations include experimental and theoretical studies of more than 100 representative geometries, from single and multiple helices, toroids, boxes, pyramids and conical spirals to structures that resemble spherical baskets, cars, houses, cuboid cages, flowers, scaffolds, each with single- and/or multiple-level configurations.  We further introduce concepts in physical transfer, patterned photopolymerization and non-linear plasticity to enable integration of 3D mesostructures onto nearly any class of substrate, with additional capabilities in access to fully or partially free-standing forms, all via mechanisms quantitatively described by theoretical modeling.  Compatibility with the well-established technologies available in the semiconductor industries suggest a broad range of application opportunities.  Illustrations of these ideas include their use in building 3D structures as radio frequency devices for tunable electromagnetic properties, as open-architecture electronic scaffolds for formation of dorsal root ganglion (DRG) neural networks, as ultra-stretchable interconnects for soft electronics and as catalyst supports for propulsive systems in 3D micro-swimmers with geometrically controlled dynamics.