BY WEIGHT, it is 100 times stronger than steel, yet it can stretch by as much as a quarter of its length. Graphene is the thinnest solid ever known, indeed the thinnest possible: it is a sheet of linked carbon atoms just one atom thick. It is a great conductor of electricity and nearly transparent to visible light, but is impermeable to gases and liquids. It has so many surprising properties that it has been dubbed a "wonder material" and has earned its discoverers a Nobel prize. Graphene-related patents have shot up from 3,018 in 2011 to 8,416 in 2014, the year the European Union launched a ten-year, billion-euro project to unravel the wonder material's mysteries. Why does graphene stir such interest?

The fuss began in 2003 when Andre Geim and his student Konstantin Novoselov, physicists at the Manchester University, first peeled layers of the stuff from graphite using sticky tape. Atom-thick sheets were thought so unlikely to be stable that the pair's report was rejected, twice, by the journal Nature. Once the Manchester pair was proved right, a flurry of studies began to measure the properties of the stuff. Graphene was found to be incredibly strong, and electric current zipped across it with virtually no loss, up to 200-times faster than in silicon—not far off the speed of light. The material's strength was soon touted in graphene-enhanced sports kit such as tennis racquets and skis. Graphene is not good at controlling or switching electric current, so making faster computers with it remains tricky. But applications such as touchscreens exploit its conductive nature. The material has found its way into better, lighter batteries and, in a few months' time, the first graphene light bulb will go on sale.

Plenty of research is going into joining other atoms to the graphene lattice, to make it do what electrical engineers would like. The material could help with water purification and desalination efforts; thin graphene sheets with holes just large enough for water molecules could sequester pollutants, while thin tubes lined with it could draw up water and leave salt behind. Its pliable nature makes it suitable for wearable electronics with flexible displays—or even transparent ones. Pairs of electrons moving through graphene can be made to split up, making for "entangled states" that physicists would like to put to use in so-called quantum computers. There are biological applications, too; a team at the Michigan Technological University is experimenting with a graphene-bound polymer that regenerates nerve cells in patients with spinal-cord injuries. Even birth control could be improved by graphene's strength and impermeability to liquids; in 2013, the Gates Foundation put $100,000 into an effort to develop a graphene-enhanced condom.

Ideas for using graphene are proliferating almost at the speed at which electrons move within it. Detractors insist that interest in the material is a bubble bound to burst, and that claiming graphene as an ingredient in a product is more about marketing than innovation. But naysayers would do well to remember the history of silicon, which was purified a full century before it found much use; now it is the centrepiece of the global electronics industry. An understanding of what graphene is capable of, and how to make lots of it, has bloomed in far less time. If even a fraction of the applications envisaged for it take off, graphene will have earned its nickname as a wonder material.