However, the measurements are yet another demonstration of the remarkable properties of graphene. “We knew graphene was the strongest material; this work confirms it,” says Konstantin Novoselov, a fellow at the University of Manchester, who was the first to isolate two-dimensional sheets of the material.
The material’s strength is particularly good news for those in the semiconductor industry who hope to make computers faster by developing microprocessors that use graphene transistors. “The main liability concerning the microprocessing industry is strain,” says Julia Greer, a materials scientist at Caltech. Not only must the materials used to make transistors have good electrical properties, but they must also be able to survive the stresses of manufacturing processes and the heat generated by repeated operations. The processes used to pattern metal electrical connections onto microprocessors, for example, exert stresses that can cause chips to fail. And, says Greer, the main obstacle to making faster microprocessors is that “the heat is too much for materials to take.” Based on measurements of its strength, graphene transistors could take the heat.
Graphene is the basic building block of several other three-dimensional nanostructures made up of carbon, including nanotubes and buckyballs, hollow soccer-ball-shaped molecules. “In theory, a nanotube is rolled-up graphene, so it should have the same strength,” says Hone. In reality, however, most nanotubes have tiny flaws–an atom missing here or there. “When you pull on a nanotube,” says Hone, it breaks at any site where there’s a defect.
The mechanical strength of graphene on the nanoscale could prove useful for applications other than in transistors for microprocessors. The material could, for example, serve as a durable, mechanically operated electrical switch for communications devices including cell phones and advanced radar, says Kysar.
Although most research on nanomaterials has focused on their electrical, optical, and chemical properties, “mechanical properties control more than it might appear,” says Greer. Existing databases of materials’ strength don’t account for differences in strength at the nanoscale. But now, at least, researchers testing the strength of nanomaterials will have a record to shoot for.