David Kirkpatrick

November 10, 2009

Carbon nanotubes are the wiring of the future

Filed under: et.al. — Tags: , , , , — David Kirkpatrick @ 3:16 pm

Previously I’ve blogged about carbon nanotubes replacing copper wiring, and here’s news of a new manufacturing technique that gets that idea closer to the mainstream. This shift in wiring is most likely a “when” instead of an “if.”

From the second link:

A new method for assembling carbon nanotubes has been used to create fibers hundreds of meters long. Individual carbon nanotubes are strong, lightweight, and electrically conductive, and could be valuable as, among other things, electrical transmission wires. But aligning masses of the nanotubes into well-ordered materials such as fibers has proven challenging at a scale suitable for manufacturing. By processing carbon nanotubes in a solution called a superacid, researchers at Rice University have made long fibers that might be used as lightweight, efficient wires for the electrical grid or as the basis of structural materials and conductive textiles.

Others have made carbon-nanotube fibers by pulling the tubes from solid hair-like arrays or by spinning them like wool as they emerge from a chemical reactor. The problem with starting from a solid, says Rice chemical engineering professor Matteo Pasquali, is that “the alignment is not spectacular, and these methods are difficult to scale up.” The better aligned and ordered the individual nanotubes in a larger structure, the better the collective structure’s electrical and mechanical properties. Using the Rice methods, well-aligned nanotube fibers can be made on a large scale, shot out from a nozzle similar to a showerhead.

The late Nobel laureate Richard Smalley started the Rice project in 2001. Smalley knew solution-processing would be a good way to assemble nanotube fibers and films because of nanotubes’ shape. Carbon nanotubes are much longer than they are wide, so when they’re in a flowing solution, they line up like logs floating down a river. But carbon nanotubes aren’t soluble in conventional solvents. The Rice group laid the foundations for liquid processing of the nanotubes five years ago, when they discovered that sulfuric acid brings the nanotubes into solution by coating their surfaces with positively charged ions.


Nanotube fiber: This fiber, which is about 40 micrometers in diameter, is made up of carbon nanotubes.
Credit: Rice University

March 29, 2008

Will carbon nanotubes replace copper wiring?

Filed under: Technology — Tags: , , , — David Kirkpatrick @ 5:09 pm

I received email yesterday on a nanotech development. Nanocomp Technologies has been given an Air Force contract to develop electrically conductive wire and other materials from carbon nanotubes.

The major aspect of this contract is an effort to replace copper wiring and its attendant limitations — weighty, physically breaks down, etc. If Nanocomp Technologies is successful the entire aerospace industry will be one of the first beneficiaries of this development.

The release:

Nanocomp Technologies Awarded Small Business Innovation Research (SBIR)
Contract from United States Air Force

Project to Assess Carbon Nanotube Wiring for Improved Electrical Power
Generation and Alternatives to Traditional Copper Applications

CONCORD, N.H.–(BUSINESS WIRE)–Nanocomp Technologies, Inc.
(www.nanocomptech.com), a developer of energy-saving performance
materials and component products, today announced it has been awarded a
Phase One contract by the United States Air Force under the Department
of Defense’s Small Business Innovation Research (SBIR) program. The
intent of this SBIR project is to develop a new generation of very
lightweight, electrically conductive wires, cables and materials made
from carbon nanotubes (CNTs). Under Phase One, Nanocomp Technologies
will expand upon its current processing and manufacturing methods for
producing CNT sheets and spun conductors, composed of long-length CNTs,
to surpass established electrical performance standards required by
aerospace to replace traditional copper wiring.

Copper wiring is used in electronic harnesses because of its proven
history and excellent electrical conductivity. However, in modern
aerospace systems, wiring deficiencies are becoming more apparent as
functional demands increase. For example, today’s large satellites
weighing 15 tons or more derive one-third of their weight from copper
wiring harnesses. Similarly in commercial aircraft, a Boeing 747 uses as
much as 135 miles of copper wire and weighs more than 4000 lbs. Copper
wires also oxidize and corrode, are susceptible to vibration fatigue and
create premature electronics failures due to overheating conditions.

Nanocomp Technologies’ carbon nanotubes are already distinguished by
their long length-up to one millimeter. As a result, the company’s
products are significantly more conductive in end applications as
compared to short, powder-like nanotubes appearing in today’s market.
In early 2008, Nanocomp began producing large CNT sheets that not only
demonstrate value for a number of aerospace and electronics
applications, but also will integrate directly into existing
manufacturing processes in those industries.

“We are thrilled to have received this important program award from
the USAF,” said Peter Antoinette, president and CEO of Nanocomp
Technologies. “It is generally overlooked that modern satellites and
aircraft rely upon an invention from the 1800s – copper-based electrical
wires and cables. Our work can result in a true 21st century change in
the game, creating electrically optimized carbon nanotube wires and
cables, comparable to copper in terms of electrical conductivity but up
to 80 percent lighter and more robust. The result will be increased
mission capability for the Air Force and dramatic fuel savings for the
entire aerospace industry. The project demonstrates the U.S.
government’s commitment to enabling innovations in materials
science, and speaks to their confidence in our cutting edge efforts to
develop performance products that save energy.”

The SBIR program is funded by 12 federal agencies from their Research
and Development budgets. It is designed to simultaneously stimulate
technological innovation among private sector small businesses such as
Nanocomp Technologies and increase the commercialization of new
technology through federal R&D.

About Nanocomp Technologies, Inc.

Nanocomp Technologies, Inc. was formed in 2004 to leverage its
proprietary and fundamental advancements in the production of long
carbon nanotubes as well as a unique ability to fabricate them into
physically strong, lightweight and electro-thermally conductive yarns
and nonwoven sheets. The company’s objective is to develop products
with revolutionary performance benefits that would create a new
generation of advanced structural materials and electro-thermal devices.
It has 16 patents pending. The company is headquartered in Concord, N.H.
For additional information, please visit http://www.nanocomptech.com/.

Nanocomp and the Nanocomp logo are trademarks of Nanocomp Technologies,
Inc. All other marks are trademarks or registered trademarks of their
respective holders.

*************************

March 7, 2010

Carbon nanotubes open new area of energy research

Nanotechnology is revolutionizing how we see and deal with electricity, everything from storage to wiring. Now a team at MIT has discovered carbon nanotubes produce electricity in an entirely new way, opening a brand new area in energy research.

From the final link:

A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.

The phenomenon, described as thermopower waves, “opens up a new area of energy research, which is rare,” says Michael Strano, MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in  on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.

Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.

The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter () in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades.

November 27, 2009

Semiconducting nanowires are coming

With all the news about nanotechnology and wiring that’s been coming out over the last year or so, this release is no surprise.

The release:

November 26, 2009

Nanowires key to future transistors, electronics

WEST LAFAYETTE, Ind. –

Nanowire formation
Download photo
caption below

A new generation of ultrasmall transistors and more powerful computer chips using tiny structures called semiconducting nanowires are closer to reality after a key discovery by researchers at IBM, Purdue University and the University of California at Los Angeles.The researchers have learned how to create nanowires with layers of different materials that are sharply defined at the atomic level, which is a critical requirement for making efficient transistors out of the structures.

 

“Having sharply defined layers of materials enables you to improve and control the flow of electrons and to switch this flow on and off,” said Eric Stach, an associate professor of materials engineering at Purdue.

Electronic devices are often made of “heterostructures,” meaning they contain sharply defined layers of different semiconducting materials, such as silicon and germanium. Until now, however, researchers have been unable to produce nanowires with sharply defined silicon and germanium layers. Instead, this transition from one layer to the next has been too gradual for the devices to perform optimally as transistors.

The new findings point to a method for creating nanowire transistors.

The findings are detailed in a research paper appearing Friday (Nov. 27) in the journal Science. The paper was written by Purdue postdoctoral researcher Cheng-Yen Wen, Stach, IBM materials scientists Frances Ross, Jerry Tersoff and Mark Reuter at the Thomas J. Watson Research Center in Yorktown Heights, N.Y, and Suneel Kodambaka, an assistant professor at UCLA’s Department of Materials Science and Engineering.

Whereas conventional transistors are made on flat, horizontal pieces of silicon, the silicon nanowires are “grown” vertically. Because of this vertical structure, they have a smaller footprint, which could make it possible to fit more transistors on an integrated circuit, or chip, Stach said.

“But first we need to learn how to manufacture nanowires to exacting standards before industry can start using them to produce transistors,” he said.

Nanowires might enable engineers to solve a problem threatening to derail the electronics industry. New technologies will be needed for industry to maintain Moore’s law, an unofficial rule stating that the number of transistors on a computer chip doubles about every 18 months, resulting in rapid progress in computers and telecommunications. Doubling the number of devices that can fit on a computer chip translates into a similar increase in performance. However, it is becoming increasingly difficult to continue shrinking electronic devices made of conventional silicon-based semiconductors.

“In something like five to, at most, 10 years, silicon transistor dimensions will have been scaled to their limit,” Stach said.

Transistors made of nanowires represent one potential way to continue the tradition of Moore’s law.

The researchers used an instrument called a transmission electron microscope to observe the nanowire formation. Tiny particles of a gold-aluminum alloy were first heated and melted inside a vacuum chamber, and then silicon gas was introduced into the chamber. As the melted gold-aluminum bead absorbed the silicon, it became “supersaturated” with silicon, causing the silicon to precipitate and form wires. Each growing wire was topped with a liquid bead of gold-aluminum so that the structure resembled a mushroom.

Then, the researchers reduced the temperature inside the chamber enough to cause the gold-aluminum cap to solidify, allowing germanium to be deposited onto the silicon precisely and making it possible to create a heterostructure of silicon and germanium.

The cycle could be repeated, switching the gases from germanium to silicon as desired to make specific types of heterostructures, Stach said.

Having a heterostructure makes it possible to create a germanium “gate” in each transistor, which enables devices to switch on and off.

The work is based at IBM’s Thomas J. Watson Research Center and Purdue’s Birck Nanotechnology Center in the university’s Discovery Park and is funded by the National Science Foundation through the NSF’s Electronic and Photonic Materials Program in the Division of Materials Research.

PHOTO CAPTION:
Researchers are closer to using tiny devices called semiconducting nanowires to create a new generation of ultrasmall transistors and more powerful computer chips. The researchers have grown the nanowires with sharply defined layers of silicon and germanium, offering better transistor performance. As depicted in this illustration, tiny particles of a gold-aluminum alloy were alternately heated and cooled inside a vacuum chamber, and then silicon and germanium gases were alternately introduced. As the gold-aluminum bead absorbed the gases, it became “supersaturated” with silicon and germanium, causing them to precipitate and form wires. (Purdue University, Birck Nanotechnology Center/Seyet LLC)

November 3, 2009

Breakthrough in large-scale nanotube processing

Via KurzweilAI.net — These manufacturing breakthroughs aren’t as exciting and sexy as a groundbreaking medical application or replacing copper wiring with carbon nanotubes or graphene, but they are key to turning nanotechnology into a viable industry.

Breakthrough In Industrial-scale Nanotube Processing
ScienceDaily, Nov. 3, 2009

Rice University scientists have unveiled a method for high-throughput industrial-scale processing of carbon-nanotube fibers, using chlorosulfonic acid as a solvent.

The process that could lead to revolutionary advances in materials science, power distribution and nanoelectronics.

 

Read Original Article>>

May 11, 2010

Graphene as a heat sink

Filed under: Science, Technology — Tags: , , , , — David Kirkpatrick @ 12:43 am

Nanotech news from UC Riverside.

The release:

Hot new material can keep electronics cool

Few atomic layers of graphene reveal unique thermal properties

IMAGE: Alexander Balandin is a professor of electrical engineering in the Bourns College of Engineering at the University of California, Riverside.

Click here for more information.

Professor Alexander Balandin and a team of UC Riverside researchers, including Chun Ning Lau, an associate professor of physics, have taken another step toward new technology that could keep laptops and other electronic devices from overheating.

Balandin, a professor of electrical engineering in the Bourns College of Engineering, experimentally showed in 2008 that graphene, a recently discovered single-atom-thick carbon crystal, is a strong heat conductor. The problem for practical applications was that it is difficult to produce large, high quality single atomic layers of the material.

Now, in a paper published in Nature Materials, Balandin and co-workers found that multiple layers of graphene, which are easier to make, retain the strong heat conducting properties.

That’s also a significant discovery in fundamental physics. Balandin’s group, in addition to measurements, explained theoretically how the materials’ ability to conduct heat evolves when one goes from conventional three-dimensional bulk materials to two-dimensional atomically-thin films, such as graphene.

The results published in Nature Materials may have important practical applications in removal of dissipated hear from electronic devices.

Heat is an unavoidable by-product when operating electronic devices. Electronic circuits contain many sources of heat, including millions of transistors and interconnecting wiring. In the past, bigger and bigger fans have been used to keep computer chips cool, which improved performance and extended their life span. However, as computers have become faster and gadgets have gotten smaller and more portable the big-fan solution no longer works.

New approaches to managing heat in electronics include incorporating materials with superior thermal properties, such as graphene, into silicon computer chips. In addition, proposed three-dimension electronics, which use vertical integration of computer chips, would depend on heat removal even more, Balandin said.

Silicon, the most common electronic material, has good electronic properties but not so good thermal properties, particularly when structured at the nanometer scale, Balandin said. As Balandin’s research shows, graphene has excellent thermal properties in addition to unique electronic characteristics.

“Graphene is one of the hottest materials right now,” said Balandin, who is also chair of the Material Sciences and Engineering program. “Everyone is talking about it.”

Graphene is not a replacement for silicon, but, instead could be used in conjunction with silicon, Balandin said. At this point, there is no reliable way to synthesize large quantities of graphene. However, progress is being made and it could be possible in a year or two, Balandin said.

Initially, graphene would likely be used in some niche applications such as thermal interface materials for chip packaging or transparent electrodes in photovoltaic solar cells, Balandin said. But, in five years, he said, it could be used with silicon in computer chips, for example as interconnect wiring or heat spreaders. It may also find applications in ultra-fast transistors for radio frequency communications. Low-noise graphene transistors have already been demonstrated in Balandin’s lab.

Balandin published the Nature Materials paper with two of his graduate students Suchismita Ghosh, who is now at Intel Corporation, and Samia Subrina, Lau. one of her graduate students, Wenzhong Bao, and Denis L. Nika and Evghenii P. Pokatilov, visting researchers in Balandin’s lab who are based at the State University of Moldova.

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The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California’s diverse culture, UCR’s enrollment of over 19,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.