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Billionth-of-a-meter-thick gold layers created in ten minutes


June 21, 2010

Diagram of the gold monolayering process

Diagram of the gold monolayering process

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We’ve reported on some rather questionable products of gold plating technology before, including a gilded iPhone, Wii gaming system and barbecue. There are legitimate reasons to coat things in gold, however, such as in the production of nanoelectronics and semiconductors. The coatings used in these applications are infinitely thinner than what you would typically use on an iPhone, so it is of the utmost importance that they be as smooth and uniform as possible. Recently, researchers at Troy, New York’s Rensselaer Polytechnic Institute announced that they have devised a quick and simple method of producing just such coatings.

Sang-Kee Eah, an assistant professor in the Department of Physics, Applied Physics and Astronomy collaborated with graduate student Matthew N. Martin on the project. They infused liquid toluene, an industrial solvent, with gold nanoparticles. The particles formed a flat, closely-packed layer on the liquid’s surface. By putting droplets of the gold-infused toluene on various surfaces, then waiting for the liquid to evaporate and leave behind the nanoparticles, they were able to create a monolayer of gold mere billionths of a meter thick in just ten minutes. These monolayers worked on a variety of surfaces, including a three-inch silicone wafer.

Not only is the Rensselaer method faster than others, some of which can take up to several hours, but it also doesn’t require any post-synthesis cleaning.

“The extension of this droplet 2-D self-assembly method to other kinds of nanoparticles, such as magnetic and semiconducting particles, is challenging but holds much potential,” said Eah. “Monolayer films of magnetic nanoparticles, for instance, are important for magnetic data storage applications. Our new method may be able to help inform new and exciting applications.”

Results of the study, titled “Charged gold nanoparticles in non-polar solvents: 10-min synthesis and 2-D self-assembly,” were published recently in the journal Langmuir.

Below is a video of the new fabrication process.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth
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