Materials scientists have been singing graphene’s praises since it was first isolated in 2005. The one-atom-thick sheets of carbon conduct electrons better than silicon and have been made into fast, low-power transistors. Now, for the first time, researchers have measured the intrinsic strength of graphene, and they’ve confirmed it to be the strongest material ever tested. The finding provides good evidence that graphene transistors could take the heat in future ultrafast microprocessors.
Jeffrey Kysar and James Hone, mechanical-engineering professors at Columbia University, tested graphene’s strength at the atomic level by measuring the force that it took to break it. They carved one-micrometer-wide holes into a silicon wafer, placed a perfect sample of graphene over each hole, and then indented the graphene with a sharp probe made of diamond. Such measurements had never been taken before because they must be performed on perfect samples of graphene, with no tears or missing atoms, say Kysar and Hone.
Hone compares his test to stretching a piece of plastic wrap over the top of a coffee cup, and measuring the force that it takes to puncture it with a pencil. If he could get a large enough piece of the material to lay over the top of a coffee cup, he says, graphene would be strong enough to support the weight of a car balanced atop the pencil.
It’s unlikely that graphene’s incredible strength will be put to use in such a task. At the macroscopic level of coffee cups and cars, “any material will be full of cracks and flaws,” says Kysar. It’s at the level of such cracks and flaws that airplane wings and bridge supports fail. “Only a tiny sample can be perfect and superstrong,” says Hone.