If you think you're good at precision welding, think again. Beverley Inkson can connect nanowires together with microscopic bits of melted tin. Her tricks could be used to repair electronics and build tiny sensors.

"Scientists have developed many ways to make individual nano-objects, but not many ways to securely join them together," said Inkson. "Most everyday joining techniques cannot be applied at the nanoscale, where nano-objects, a thousand times smaller than a human hair are easily destroyed by heat."

Her team at Sheffield University can connect those fragile objects without damaging them. They explained how to do it in a report to Nano Letters this month.

Other researchers have fused sturdy, 650-nanometer, platinum wires together, but their techniques would melt smaller objects. Inkson can join gold or alloy wires that are only 55 nanometers wide, roughly the same width as the lines in your desktop's processor.

By laying a nanowire across the objects that she wants to weld, and then passing just the right pulse of electricity through it, Inkson can connect the minuscule objects. She uses a tool called a nanomanipulator to pick the wires up, move them around, and electrify them.

"The solder wire melts and flows onto the joint," says Inkson. "The welding can be watched in real-time inside an electron microscope, allowing the choice of exactly where, and how much, nanosolder is applied."

Top: Scanning Electron Microscope image of weleded gold nanowires that spell out the word NANO. Bottom: The cone-shaped tips of a nanomanipulator move a sacrificial nanowire into place and electrically heat it to join two other wires together. Courtesy of Beverley Inkson

Citation: Yong Peng, Tony Cullis and Beverley Inkson, Bottom-up Nanoconstruction by the Welding of Individual Metallic Nanoobjects Using Nanoscale Solder, Nano Lett., Article ASAP

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