Nano Bugle

A window into applied science supported by INL

Scientists Strive to Replace Silicon with Graphene on Nanocircuity

In a technique known as thermochemical nanolithography, the tip of an atomic force microscope uses heat to turn graphene oxide into reduced graphene oxide, a substance that can be used to produce nanocircuits and nanowires with controllable conductivity.

Credit: University of Illinois at Urbana-Champaign

 

 

 

 

 

Scientists have made a breakthrough toward creating nanocircuitry on graphene, widely regarded as the most promising candidate to replace silicon as the building block of transistors. They have devised a simple and quick one-step process based on thermochemical nanolithography (TCNL) for creating nanowires, tuning the electronic properties of reduced graphene oxide on the nanoscale and thereby allowing it to switch from being an insulating material to a conducting material.

The technique works with multiple forms of graphene and is poised to become an important finding for the development of graphene electronics. The research appears in the June 11, 2010, issue of the journal Science.

Scientists who work with nanocircuits are enthusiastic about graphene because electrons meet with less resistance when they travel along graphene compared to silicon and because today’s silicon transistors are nearly as small as allowed by the laws of physics. Graphene also has the edge due to its thickness – it’s a carbon sheet that is a single atom thick. While graphene nanoelectronics could be faster and consume less power than silicon, no one knew how to produce graphene nanostructures on such a reproducible or scalable method. That is until now.

“We’ve shown that by locally heating insulating graphene oxide, both the flakes and epitaxial varieties, with an atomic force microscope tip, we can write nanowires with dimensions down to 12 nanometers. And we can tune their electronic properties to be up to four orders of magnitude more conductive. We’ve seen no sign of tip wear or sample tearing,” said Elisa Riedo, associate professor in the School of Physics at the Georgia Institute of Technology.

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“This project is an excellent example of the new technologies that epitaxial graphene electronics enables,” said Walt de Heer, Regent’s Professor in Georgia Tech’s School of Physics and the original proponent of epitaxial graphene in electronics. His study led to the establishment of the Materials Research Science and Engineering Center two years ago. “The simple conversion from graphene oxide to graphene is an important and fast method to produce conducting wires. This method can be used not only for flexible electronics, but it is possible, sometime in the future, that the bio-compatible graphene wires can be used to measure electrical signals from single biological cells.”

 The research is a collaboration among the Georgia Tech, the U.S. Naval Research Laboratory and the University of Illinois at Urbana-Champaign. Other members of the research team include: Zhongqing Wei, Debin. Wang, Suenne Kim, Soo-Young Kim, Yike Hu, Michael K. Yakes, Arnaldo R.Laracuente, Zhenting Dai, Seth R. Marder, Claire Berger, and Walter A. de Heer.

Author Georgia Tech

You can read the full article here.

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June 17, 2010 Posted by | Nano News | Leave a comment

Converting sea water into fresh water with Nanotechnology

The most common desalination technology, known as reverse osmosis, involves applying pressure to seawater to force salt ions through a membrane. Although portable reverse-osmosis devices are available, most work slowly and have trouble filtering out water pollutants.

Jongyoon Han from Massachusetts Institute of Technology and his team had developed another technology: ion channel polarization (ICP) and reported their findings online in Nature Nanotechnology.

To test if ICP could remove salt and other charged contaminants in water, such as bacteria and certain pollutants, they added blood cells to seawater and tagged them with fluorescent dye.

Then, they forced saltwater to pass through the ion-repulsion area. On one side was a very salty, fluorescent mixture, and on the other side was clean water.

However there is still need to put the water through a charcoal filter to eliminate neutral materials, such as hydrocarbons, from industrial pollution.

It should be necessary to integrate around 1600 nano-units onto a 20-centimeter wafer to generate about 300 milliliters of water per minute.

Credit: Mark A. Shannon, Nature Nanotechnology, 5; (inset) Sung Jae Kim/MIT

June 15, 2010 Posted by | Nano News | Leave a comment

Coming Soon: A Foldable iPad?

During the last decade, we have seen how LCD technology has revolutionized our daily lives, with applications from cell phones to television displays.  It seems that the next move of the industry points to foldable screens. The technology tend might be even accelerated by the great market acceptance of the iPad.

In this race for the production of affordable and efficient foldable displays, a team of Duke University chemists presented in Advanced Materials a way to mass-produce bendable copper nanowires. Their technology is based on the production of copper nanowires in a water solution. By adding different chemicals to the solution, Duke researchers created tiny crystal “seeds,” which sprouted individual nanowires. The researchers hope the technology can be used to produce new materials with direct applications in mobile phones, portable computers as well as in the fast-growing solar industry, too.

You can read the full article here.

June 7, 2010 Posted by | Uncategorized | 1 Comment

Nanotechnology applied to oil spills

According to a recent post appeared on the Christian Science Monitor,  BP received around 31,600 suggestions from people around the world on how to cap the well and clean up the crisis caused by the BP oil spill. It seems that, of the 31,600 ideas, 8,000 have been submitted on paper. Among the solutions proposed there are very short-tempered or imaginative options like the destruction of the well with nuclear and conventional explosives or giant vacuum systems inspired in Kevin Costner movie Waterworld.

From Nanobugle, we propose nanotechnology base solutions similar to the recent work published in Advanced Materials by a team of the Key Laboratory for Advanced Materials Processing Technology (Department of Mechanical Engineering) at Tsinghua University and the Department of Advanced Materials and Nanotechnology at Peking University.

The Chinese group created a porous, sponge-like bulk material of self-assembled CNTs that might be used at an ocean spill to attract oil. The CNT-sponge expands to hold nearly 200 times its weight and 800 times the volume of the stuff, moves automatically towards higher concentrations of the oil and can be squeezed clean. Furthermore it can be reused repeatedly because, apparently. these sponges show no strength degradation after compression at a set strain of 60% for 1000 cycles.

June 4, 2010 Posted by | Uncategorized | 1 Comment

How butterflies’ wings could cut bank fraud

University of Cambridge scientists, Mathias Kolle, working with Professor Ullrich Steiner and Professor Jeremy Baumberg, have discovered a way of mimicking the stunningly bright and picturesque colors found on the wings of some tropical butterflies. Their findings about the complex, microscopic structures discovered could have important applications in the security printing industry, helping to make bank notes and credit cards harder to forge.

Inspired by the natural structures of the Indonesian Peacock or the Swallowtail butterfly (Papilio blumei) and using a combination of nanofabrication techniques- including self-assembly and atomic layer deposition – the aforementioned researchers made structurally identical copies of the butterfly scales, and these copies produced the same vivid colors as the butterflies’ wings.

Results were published in Nature Nanotechnology and the Engineering and Physical Sciences Research Council and the Cambridge Newton Trust funded the research. You can read the full article here.

June 2, 2010 Posted by | Uncategorized | Leave a comment