Hollow, sandwich-like nanostructure that is joined by periodic, rigid webbing to increase bending stiffness and prevent fracture.

Mechanical metamaterials are increasingly used for structural applications. In particular, sandwich structures consisting of two planar face sheets connected by a webbing or foam core, can provide an optimal design for applications that require low weight and high-stiffness. Despite their utility, currently available sandwich plates are prone to fracture or permanent deformation when mechanically loaded and have not been scaled to the nanometer scale.

To overcome this issue, a new “nanocardboard” sandwich-like structure, has been invented. The nanocardboard is composed of two nanometer thick plates that are separated by a microscale gap and joined by rigid, periodic webbing. The meta-material is fabricated in a single step of atomic layer deposition of alumina on a silicon mold that contains the webbing.

The optimal webbing can be a honeycomb lattice, basket-weave pattern or cylinders packed in hexagonal packing. The final, optimized basketweave webbing structure is ultrathin, ultralight, has a high bending stiffness, and resists fracture and deformation when mechanically loaded. Furthermore, the material exhibits excellent thermal-insulating properties, making it well suited for high heat applications and electrical insulation.

• Improved resilience to fracture and deformation during loading or shearing of the material
• Single-step fabrication
• Ultrathin and ultralight (~1 g m-2)
• Excellent thermal and electrical insulator

• Nano- and micro-electromechanical systems
• Nanoscale thermal insulation
• Biological membranes
• Nanorobotics and microflyer wings
• Scanning probe cantilevers
• Interstellar lightsails