Wired to the nano future

Scientists have accidentally created what could be the finest metallic wires yet made, a million times thinner than a human hair.

The discovery by teams at Birmingham and St Andrews universities may prove to be significant for the future miniaturisation of electronic devices.

It is not yet known if the ultrafine silver will retain its metallic properties at such small dimensions.

Group leader Peter Edwards, professor of chemistry and materials at Birmingham, said work had begun to explore the electrical and magnetic properties associated with the wires.

"The ability to manufacture bare, perfectly crystalline, ultra-small wires of metal opens up not only the prospect of interesting science but also potentially new areas of manufacturing and engineering technology on an unbelievably tiny scale," he said.

The discovery was made by graduate student Michael Edmondson and scientist Wuzong Zhov. He was developing a technique to impregnate zeolites - a common material honeycombed with porous filaments - with silver nitrate. The aim was to create a network of silver wires within the zeolite.

However, when he analysed the sample with an electron-beam microscope, pure, single crystal nanowires of silver grew out from the material within a matter of seconds.

It seems the highly focused electron beam reduces silver ions into a crystalline form in a similar way to that used to form latent images in photography.

The silver rapidly builds up layer by layer, fracturing the surface of the zeolite and emerging in fine filaments, a few thousand atoms across and perhaps a million times as long.

Professor Edwards said the goal was to assemble dense bundles of metallic nanowires that could carry enough current.

"We will aim to put at least 100 million silver wires through the eye of a needle," he said.

The findings are published in the journal Advanced Materials .