A team of engineers at Stanford has demonstrated a promising new nanowire welding technique that harnesses plasmonics to fuse the wires with a simple blast of light.
At the heart of the technique is the physics of plasmonics, the interaction of light and metal in which the light flows across the surface of the metal in waves, like water on the beach.
“When two nanowires lay crisscrossed, we know that light will generate plasmon waves at the place where the two nanowires meet, creating a hot spot. The beauty is that the hot spots exist only when the nanowires touch, not after they have fused. The welding stops itself. It’s self-limiting,” explained Mark Brongersma, an associate professor of materials science engineering at Stanford and an expert in plasmonics.
“The rest of the wires and, just as importantly, the underlying material are unaffected,” noted Michael McGehee, a materials engineer and also senior author of the paper. “This ability to heat with precision greatly increases the control, speed and energy efficiency of nanoscale welding.”
To demonstrate the possibilities, they applied their mesh on Saran wrap. They sprayed a solution containing silver nanowires in suspension on the plastic and dried it. After illumination, what was left was an ultrathin layer of welded nanowires.
“Then we balled it up like a piece of paper. When we unfurled the wrap, it maintained its electrical properties,” said co-author Yi Cui, an associate professor materials science and engineering. “And when you hold it up, it’s virtually transparent.”
This could lead to inexpensive window coatings that generate solar power while reducing glare for those inside, the researchers said.
In a similar vein of research, Justin Hall-Tipping of "Nanoholdings" explains some of the aims of nanotechnology here: