David Kirkpatrick

October 22, 2010

Cool nanotech image — graphene transistors

Filed under: et.al., Science — Tags: , , , , — David Kirkpatrick @ 9:34 am

The article connected to the image is pretty good, too.

Triple transistor: Single graphene transistors like this one can be made to operate in three modes and perform functions that usually require multiple transistors in a circuit.
Credit: Alexander Balandin

Also from the link:

Researchers have already made blisteringly fast graphene transistors. Now they’ve used graphene to make a transistor that can be switched between three different modes of operation, which in conventional circuits must be performed by three separate transistors. These configurable transistors could lead to more compact chips for sending and receiving wireless signals.

Chips that use fewer transistors while maintaining all the same functions could be less expensive, use less energy, and free up room inside portable electronics like smart phones, where space is tight. The new graphene transistor is an analog device, of the type that’s used for wireless communications in Bluetooth headsets and radio-frequency identification (RFID) tags.

 

September 1, 2010

More memory news …

… to join this earlier post from today on memristor storage, this one on silicon nanocrystals and 3D storage.

From the second link, the release:

Silicon oxide circuits break barrier

Nanocrystal conductors could lead to massive, robust 3-D storage

Rice University scientists have created the first two-terminal memory chips that use only silicon, one of the most common substances on the planet, in a way that should be easily adaptable to nanoelectronic manufacturing techniques and promises to extend the limits of miniaturization subject to Moore’s Law.

Last year, researchers in the lab of Rice Professor James Tour showed how electrical current could repeatedly break and reconnect 10-nanometer strips of graphite, a form of carbon, to create a robust, reliable memory “bit.” At the time, they didn’t fully understand why it worked so well.

Now, they do. A new collaboration by the Rice labs of professors Tour, Douglas Natelson and Lin Zhong proved the circuit doesn’t need the carbon at all.

Jun Yao, a graduate student in Tour’s lab and primary author of the paper to appear in the online edition of Nano Letters, confirmed his breakthrough idea when he sandwiched a layer of silicon oxide, an insulator, between semiconducting sheets of polycrystalline silicon that served as the top and bottom electrodes.

Applying a charge to the electrodes created a conductive pathway by stripping oxygen atoms from the silicon oxide and forming a chain of nano-sized silicon crystals. Once formed, the chain can be repeatedly broken and reconnected by applying a pulse of varying voltage.

The nanocrystal wires are as small as 5 nanometers (billionths of a meter) wide, far smaller than circuitry in even the most advanced computers and electronic devices.

“The beauty of it is its simplicity,” said Tour, Rice’s T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. That, he said, will be key to the technology’s scalability. Silicon oxide switches or memory locations require only two terminals, not three (as in flash memory), because the physical process doesn’t require the device to hold a charge.

It also means layers of silicon-oxide memory can be stacked in tiny but capacious three-dimensional arrays. “I’ve been told by industry that if you’re not in the 3-D memory business in four years, you’re not going to be in the memory business. This is perfectly suited for that,” Tour said.

Silicon-oxide memories are compatible with conventional transistor manufacturing technology, said Tour, who recently attended a workshop by the National Science Foundation and IBM on breaking the barriers to Moore’s Law, which states the number of devices on a circuit doubles every 18 to 24 months.

“Manufacturers feel they can get pathways down to 10 nanometers. Flash memory is going to hit a brick wall at about 20 nanometers. But how do we get beyond that? Well, our technique is perfectly suited for sub-10-nanometer circuits,” he said.

Austin tech design company PrivaTran is already bench testing a silicon-oxide chip with 1,000 memory elements built in collaboration with the Tour lab. “We’re real excited about where the data is going here,” said PrivaTran CEO Glenn Mortland, who is using the technology in several projects supported by the Army Research Office, National Science Foundation, Air Force Office of Scientific Research, and the Navy Space and Naval Warfare Systems Command Small Business Innovation Research (SBIR) and Small Business Technology Transfer programs.

“Our original customer funding was geared toward more high-density memories,” Mortland said. “That’s where most of the paying customers see this going. I think, along the way, there will be side applications in various nonvolatile configurations.”

Yao had a hard time convincing his colleagues that silicon oxide alone could make a circuit. “Other group members didn’t believe him,” said Tour, who added that nobody recognized silicon oxide’s potential, even though it’s “the most-studied material in human history.”

“Most people, when they saw this effect, would say, ‘Oh, we had silicon-oxide breakdown,’ and they throw it out,” he said. “It was just sitting there waiting to be exploited.”

In other words, what used to be a bug turned out to be a feature.

Yao went to the mat for his idea. He first substituted a variety of materials for graphite and found none of them changed the circuit’s performance. Then he dropped the carbon and metal entirely and sandwiched silicon oxide between silicon terminals. It worked.

“It was a really difficult time for me, because people didn’t believe it,” Yao said. Finally, as a proof of concept, he cut a carbon nanotube to localize the switching site, sliced out a very thin piece of silicon oxide by focused ion beam and identified a nanoscale silicon pathway under a transmission electron microscope.

“This is research,” Yao said. “If you do something and everyone nods their heads, then it’s probably not that big. But if you do something and everyone shakes their heads, then you prove it, it could be big.

“It doesn’t matter how many people don’t believe it. What matters is whether it’s true or not.”

Silicon-oxide circuits carry all the benefits of the previously reported graphite device. They feature high on-off ratios, excellent endurance and fast switching (below 100 nanoseconds).

They will also be resistant to radiation, which should make them suitable for military and NASA applications. “It’s clear there are lots of radiation-hardened uses for this technology,” Mortland said.

Silicon oxide also works in reprogrammable gate arrays being built by NuPGA, a company formed last year through collaborative patents with Rice University. NuPGA’s devices will assist in the design of computer circuitry based on vertical arrays of silicon oxide embedded in “vias,” the holes in integrated circuits that connect layers of circuitry. Such rewritable gate arrays could drastically cut the cost of designing complex electronic devices.

###

Zhengzong Sun, a graduate student in Tour’s lab, was co-author of the paper with Yao; Tour; Natelson, a Rice professor of physics and astronomy; and Zhong, assistant professor of electrical and computer engineering.

The David and Lucille Packard Foundation, the Texas Instruments Leadership University Fund, the National Science Foundation, PrivaTran and the Army Research Office SBIR supported the research.

Read the abstract here: http://pubs.acs.org/journal/nalefd

High-resolution images are available for download here:
https://stage.media.rice.edu/images/media/NewsRels/0830_F2.jpg
https://stage.media.rice.edu/images/media/NewsRels/0830_F2a.jpg
https://stage.media.rice.edu/images/media/NewsRels/0830_F2b.jpg
https://stage.media.rice.edu/images/media/NewsRels/0830_F2c.jpg
https://stage.media.rice.edu/images/media/NewsRels/0830_F2d.jpg

NOTE: The first image (F2) is a key to the other four.

CAPTION: A 1k silicon oxide memory has been assembled by Rice and a commercial partner as a proof-of-concept. Silicon nanowire forms when charge is pumped through the silicon oxide, creating a two-terminal resistive switch. (Images courtesy Jun Yao/Rice University)

(Note: I recommend hitting the link for the first image — 0830_F2.jpg. It’s too big to run in this blog full-size, but it’s a great illustration of the chip.)

July 15, 2010

Acid bath may lead to armchair quantum wires

More nanotech news.

The release:

Nanotubes pass acid test

Rice researchers’ method untangles long tubes, clears hurdle toward armchair quantum wire

HOUSTON – (July 14, 2010) – Rice University scientists have found the “ultimate” solvent for all kinds of carbon nanotubes (CNTs), a breakthrough that brings the creation of a highly conductive quantum nanowire ever closer.

Nanotubes have the frustrating habit of bundling, making them less useful than when they’re separated in a solution. Rice scientists led by Matteo Pasquali, a professor in chemical and biomolecular engineering and in chemistry, have been trying to untangle them for years as they look for scalable methods to make exceptionally strong, ultralight, highly conductive materials that could revolutionize power distribution, such as the armchair quantum wire.

The armchair quantum wire — a macroscopic cable of well-aligned metallic nanotubes — was envisioned by the late Richard Smalley, a Rice chemist who shared the Nobel Prize for his part in discovering the the family of molecules that includes the carbon nanotube. Rice is celebrating the 25th anniversary of that discovery this year.

Pasquali, primary author Nicholas Parra-Vasquez and their colleagues reported this month in the online journal ACS Nano that chlorosulfonic acid can dissolve half-millimeter-long nanotubes in solution, a critical step in spinning fibers from ultralong nanotubes.

Current methods to dissolve carbon nanotubes, which include surrounding the tubes with soap-like surfactants, doping them with alkali metals or attaching small chemical groups to the sidewalls, disperse nanotubes at relatively low concentrations. These techniques are not ideal for fiber spinning because they damage the properties of the nanotubes, either by attaching small molecules to their surfaces or by shortening them.

A few years ago, the Rice researchers discovered that chlorosulfonic acid, a “superacid,” adds positive charges to the surface of the nanotubes without damaging them. This causes the nanotubes to spontaneously separate from each other in their natural bundled form.

This method is ideal for making nanotube solutions for fiber spinning because it produces fluid dopes that closely resemble those used in industrial spinning of high-performance fibers. Until recently, the researchers thought this dissolution method would be effective only for short single-walled nanotubes.

In the new paper, the Rice team reported that the acid dissolution method also works with any type of carbon nanotube, irrespective of length and type, as long as the nanotubes are relatively free of defects.

Parra-Vasquez described the process as “very easy.”

“Just adding the nanotubes to chlorosulfonic acid results in dissolution, without even mixing,” he said.

While earlier research had focused on single-walled carbon nanotubes, the team discovered chlorosulfonic acid is also adept at dissolving multiwalled nanotubes (MWNTs). “There are many processes that make multiwalled nanotubes at a cheaper cost, and there’s a lot of research with them,” said Parra-Vasquez, who earned his Rice doctorate last year. “We hope this will open up new areas of research.”

They also observed for the first time that long SWNTs dispersed by superacid form liquid crystals. “We already knew that with shorter nanotubes, the liquid-crystalline phase is very different from traditional liquid crystals, so liquid crystals formed from ultralong nanotubes should be interesting to study,” he said.

Parra-Vasquez, now a postdoctoral researcher at Centre de Physique Moleculaire Optique et Hertzienne, Universite’ de Bordeaux, Talence, France, came to Rice in 2002 for graduate studies with Pasquali and Smalley.

Study co-author Micah Green, assistant professor of chemical engineering at Texas Tech and a former postdoctoral fellow in Pasquali’s research group, said working with long nanotubes is key to attaining exceptional properties in fibers because both the mechanical and electrical properties depend on the length of the constituent nanotubes. Pasquali said that using long nanotubes in the fibers should improve their properties on the order of one to two magnitudes, and that similar enhanced properties are also expected in thin films of carbon nanotubes being investigated for flexible electronics applications.

An immediate goal for researchers, Parra-Vasquez said, will be to find “large quantities of ultralong single-walled nanotubes with low defects — and then making that fiber we have been dreaming of making since I arrived at Rice, a dream that Rick Smalley had and that we have all shared since.”

###

Co-authors of the paper are graduate students Natnael Behabtu, Colin Young, Anubha Goyal and Cary Pint; Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry, and Robert Hauge, a distinguished faculty fellow in chemistry, all at Rice; and Judith Schmidt, Ellina Kesselman, Yachin Cohen and Yeshayahu Talmon of the Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, Israel.

The Air Force Office of Scientific Research, the Air Force Research Laboratory, the National Science Foundation Division of Materials Research, the Robert A. Welch Foundation, the United States-Israel Binational Science Foundation and the Evans-Attwell Welch Postdoctoral Fellowship funded the research.

Read the abstract at: http://pubs.acs.org/doi/abs/10.1021/nn100864v

For more about Rice’s 25th anniversary Year of Nano celebrations, visit: http://buckyball.smalley.rice.edu/year_of_nano/

June 8, 2010

Manufacturing graphene …

Filed under: Science, Technology — Tags: , , , , — David Kirkpatrick @ 3:41 pm

… just got a little bit easier. This is good news out of Rice University. I written this many times, but there’s simply too much smoke in the graphene hype for there not to be a serious fire somewhere. I’m guessing some combination of display technology for handheld electronics is one of the best areas to monitor for market-ready graphene applications.

From the link:

Single-atom-thick sheets of carbon called graphene have some amazing properties: graphene is strong, highly electrically conductive, flexible, and transparent. This makes it a promising material to make flexible touch screens and superstrong structural materials. But creating these thin carbon sheets, and then building things out of them, is difficult to do outside the lab.

Now an advance in making and processing graphene in solution may make it practical to work with the material at manufacturing scale. Researchers at Rice University have made graphene solutions 10 times more concentrated than any before. They’ve used these solutions to make transparent, conductive sheets similar to the electrodes on displays, and they’re currently developing methods for spinning the graphene solutions to generate fibers and structural materials for airplanes and other vehicles that promise to be less expensive than today’s carbon fiber.

Making material: Sheets of graphene lay atop a mat of single-walled carbon nanotubes.
Credit: N. Behabtu/Rice University

May 27, 2010

Nanotech and optics

Very cool findings about light-activated nanoshells.

The release:

Optical Legos: Building nanoshell structures

Self-assembly method yields materials with unique optical properties

IMAGE: Heptamers containing seven nanoshells have unique optical properties.

Click here for more information.

HOUSTON — (May 27, 2010) — Scientists from four U.S. universities have created a way to use Rice University’s light-activated nanoshells as building blocks for 2-D and 3-D structures that could find use in chemical sensors, nanolasers and bizarre light-absorbing metamaterials. Much as a child might use Lego blocks to build 3-D models of complex buildings or vehicles, the scientists are using the new chemical self-assembly method to build complex structures that can trap, store and bend light.

The research appears in this week’s issue of the journal Science.

“We used the method to make a seven-nanoshell structure that creates a particular type of interference pattern called a Fano resonance,” said study co-author Peter Nordlander, professor of physics and astronomy at Rice. “These resonances arise from peculiar light wave interference effects, and they occur only in man-made materials. Because these heptamers are self-assembled, they are relatively easy to make, so this could have significant commercial implications.”

Because of the unique nature of Fano resonances, the new materials can trap light, store energy and bend light in bizarre ways that no natural material can. Nordlander said the new materials are ideally suited for making ultrasensitive biological and chemical sensors. He said they may also be useful in nanolasers and potentially in integrated photonic circuits that run off of light rather than electricity.

The research team was led by Harvard University applied physicist Federico Capasso and also included nanoshell inventor Naomi Halas, Rice’s Stanley C. Moore Professor in Electrical and Computer Engineering and professor of physics, chemistry and biomedical engineering.

Nordlander, the world’s leading theorist on nanoparticle plasmonics, had predicted in 2008 that a heptamer of nanoshells would produce Fano resonances. That paper spurred Capasso’s efforts to fabricate the structure, Nordlander said.

The new self-assembly method developed by Capasso’s team was also used to make magnetic three-nanoshell “trimers.” The optical properties of these are described in the Science paper, which also discusses how the self-assembly method could be used to build even more complex 3-D structures.

Nanoshells, the building blocks that were used in the new study, are about 20 times smaller than red blood cells. In form, they resemble malted milk balls, but they are coated with gold instead of chocolate, and their center is a sphere of glass. By varying the size of the glass center and the thickness of the gold shell, Halas can create nanoshells that interact with specific wavelengths of light.

“Nanoshells were already among the most versatile of all plasmonic nanoparticles, and this new self-assembly method for complex 2-D and 3-D structures simply adds to that,” said Halas, who has helped develop a number of biological applications for nanoshells, including diagnostic applications and a minimally invasive procedure for treating cancer.

###

Additional co-authors of the new study include Rice graduate students Kui Bao and Rizia Bardhan; Jonathan Fan and Vinothan Manoharan, both of Harvard; Chihhui Wu and Gennady Shvets, both of the University of Texas at Austin; and Jiming Bao of the University of Houston. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Department of Defense, the Robert A. Welch Foundation, the Department of Energy and Harvard University.

PhysOrg covers this story here.

May 26, 2010

Graphene as quantum dots

Nanoelectronics is a major — and important — field right now, and graphene and its cousin graphane are very important materials research components. Both of the nanomaterials are getting a lot of  hype, particularly graphene, but there’s far too much smoke for there not to be at least a little fire. It’s exciting to keep watch on the news to see the breakthroughs as they happen, and eventually cover real-world, market-ready uses for graphene and graphane.

The release:

Graphane yields new potential

Rice physicists dig theoretical wells to mine quantum dots

Graphane is the material of choice for physicists on the cutting edge of materials science, and Rice University researchers are right there with the pack – and perhaps a little ahead.

Researchers mentored by Boris Yakobson, a Rice professor of mechanical engineering and materials science and of chemistry, have discovered the strategic extraction of hydrogen atoms from a two-dimensional sheet of graphane naturally opens up spaces of pure graphene that look – and act – like quantum dots.

That opens up a new world of possibilities for an ever-shrinking class of nanoelectronics that depend on the highly controllable semiconducting properties of quantum dots, particularly in the realm of advanced optics.

The theoretical work by Abhishek Singh and Evgeni Penev, both postdoctoral researchers in co-author Yakobson’s group, was published online last week in the journal ACS Nano and will be on the cover of the print version in June. Rice was recently named the world’s No. 1 institution for materials science research by a United Kingdom publication.

Graphene has become the Flat Stanley of materials. The one-atom-thick, honeycomb-like form of carbon may be two-dimensional, but it seems to be everywhere, touted as a solution to stepping beyond the limits of Moore’s Law.

Graphane is simply graphene modified by hydrogen atoms added to both sides of the matrix, which makes it an insulator. While it’s still technically only a single atom thick, graphane offers great possibilities for the manipulation of the material’s semiconducting properties.

Quantum dots are crystalline molecules from a few to many atoms in size that interact with light and magnetic fields in unique ways. The size of a dot determines its band gap – the amount of energy needed to close the circuit – and makes it tunable to a precise degree. The frequencies of light and energy released by activated dots make them particularly useful for chemical sensors, solar cells, medical imaging and nanoscale circuitry.

Singh and Penev calculated that removing islands of hydrogen from both sides of a graphane matrix leaves a well with all the properties of quantum dots, which may also be useful in creating arrays of dots for many applications.

“We arrived at these ideas from an entirely different study of energy storage in a form of hydrogen adsorption on graphene,” Yakobson said. “Abhishek and Evgeni realized that this phase transformation (from graphene to graphane), accompanied by the change from metal to insulator, offers a novel palette for nanoengineering.”

Their work revealed several interesting characteristics. They found that when chunks of the hydrogen sublattice are removed, the area left behind is always hexagonal, with a sharp interface between the graphene and graphane. This is important, they said, because it means each dot is highly contained; calculations show very little leakage of charge into the graphane host material. (How, precisely, to remove hydrogen atoms from the lattice remains a question for materials scientists, who are working on it, they said.)

“You have an atom-like spectra embedded within a media, and then you can play with the band gap by changing the size of the dot,” Singh said. “You can essentially tune the optical properties.”

Along with optical applications, the dots may be useful in single-molecule sensing and could lead to very tiny transistors or semiconductor lasers, he said.

Challenges remain in figuring out how to make arrays of quantum dots in a sheet of graphane, but neither Singh nor Penev sees the obstacles as insurmountable.

“We think the major conclusions in the paper are enough to excite experimentalists,” said Singh, who will soon leave Rice to become an assistant professor at the Indian Institute of Science in Bangalore. “Some are already working in the directions we explored.”

“Their work is actually supporting what we’re suggesting, that you can do this patterning in a controlled way,” Penev said.

When might their calculations bear commercial fruit? “That’s a tough question,” Singh said. “It won’t be that far, probably — but there are challenges. I don’t know that we can give it a time frame, but it could happen soon.”

###

Funding from the Office of Naval Research supported the work. Computations were performed at the Department of Defense Supercomputing Resource Center at the Air Force Research Laboratory.

April 22, 2010

Quantum computing improvement

This is the first quantum computing post in a couple of months. This is a promising finding.

The release:

Bizarre matter could find use in quantum computers

Rice physicists: Odd electron mix has fault-tolerant quantum registry

IMAGE: From left, Rice physicist Rui-Rui Du, graduate students Chi Zhang and Yanhua Dai, and former postdoctoral researcher Tauno Knuuttila (not pictured) have found that odd groupings of ultracold electrons could…

Click here for more information.

HOUSTON — (April 21, 2010) — There are enticing new findings this week in the worldwide search for materials that support fault-tolerant quantum computing. New results from Rice University and Princeton University indicate that a bizarre state of matter that acts like a particle with one-quarter electron charge also has a “quantum registry” that is immune to information loss from external perturbations.

The research appeared online April 21 in Physical Review Letters. The team of physicists found that ultracold mixes of electrons caught in magnetic traps could have the necessary properties for constructing fault-tolerant quantum computers — future computers that could be far more powerful than today’s computers. The mixes of electrons are dubbed “5/2 quantum Hall liquids” in reference to the unusual quantum properties that describe their makeup.

“The big goal, the whole driving force, besides deep academic curiosity, is to build a quantum computer out of this,” said the study’s lead author Rui-Rui Du, professor of physics at Rice. “The key for that is whether these 5/2 liquids have ‘topological’ properties that would render them immune to the sorts of quantum perturbations that could cause information degradation in a quantum computer.”

Du said the team’s results indicate the 5/2 liquids have the desired properties. In the parlance of condensed-matter physics, they are said to represent a “non-Abelian” state of matter.

Non-Abelian is a mathematical term for a system with “noncommutative” properties. In math, commutative operations, like addition, are those that have the same outcome regardless of the order in which they are carried out. So, one plus two equals three, just as two plus one equals three. In daily life, commutative and noncommutative tasks are commonplace. For example, when doing the laundry, it doesn’t matter if the detergent is added before the water or the water before the detergent, but it does matter if the clothes are washed before they’re placed in the dryer.

“It will take a while to fully understand the complete implications of our results, but it is clear that we have nailed down the evidence for ‘spin polarization,’ which is one of the two necessary conditions that must be proved to show that the 5/2 liquids are non-Abelian,” Du said. “Other research teams have been tackling the second condition, the one-quarter charge, in previous experiments.”

The importance of the noncommutative quantum properties is best understood within the context of fault-tolerant quantum computers, a fundamentally new type of computer that hasn’t been built yet.

Computers today are binary. Their electrical circuits, which can be open or closed, represent the ones and zeros in binary bits of information. In quantum computers, scientists hope to use “quantum bits,” or qubits. Unlike binary ones and zeros, the qubits can be thought of as little arrows that represent the position of a bit of quantum matter. The arrow might represent a one if it points straight up or a zero if it points straight down, but it could also represent any number in between. In physics parlance, these arrows are called quantum “states.” And for certain complex calculations, being able to represent information in many different states would present a great advantage over binary computing.

The upshot of the 5/2 liquids being non-Abelian is that they have a sort of “quantum registry,” where information doesn’t change due to external quantum perturbations.

“In a way, they have internal memory of their previous state,” Du said.

The conditions needed to create the 5/2 liquids are extreme. At Rice, Tauno Knuuttila, a former postdoctoral research scientist in Du’s group, spent several years building the “demagnetization refrigerator” needed to cool 5-millimeter squares of ultrapure semiconductors to within one-10,000th of a degree of absolute zero. It took a week for Knuuttila to simply cool the nearly one-ton instrument to the necessary temperature for the Rice experiments.

The gallium arsenide semiconductors used in the tests are the most pure on the planet. They were created by Loren Pfieiffer, Du’s longtime collaborator at Princeton and Bell Labs. Rice graduate student Chi Zhang conducted additional tests at the National High Magnetic Field Laboratory in Tallahassee, Fla., to verify that the 5/2 liquid was spin- polarized.

###

Study co-authors include Zhang, Knuuttila, Pfeiffer, Princeton’s Ken West and Rice’s Yanhua Dai. The research is supported by the Department of Energy, the National Science Foundation and the Keck Foundation.

March 18, 2010

Nano RFID

Sounds like this would make a trip to the grocery store a snap. These tags are based on a carbon-nanotube-infused ink for ink-jet printers.

Rice researchers, in collaboration with a team led by Gyou-jin Cho at Sunchon National University in Korea, have come up with an inexpensive, printable transmitter that can be invisibly embedded in packaging. It would allow a customer to walk a cart full of groceries or other goods past a scanner on the way to the car; the scanner would read all items in the cart at once, total them up and charge the customer’s account while adjusting the store’s inventory.

More advanced versions could collect all the information about the contents of a store in an instant, letting a retailer know where every package is at any time.

RFID tags printed through a new roll-to-roll process could replace bar codes and make checking out of a store a snap. Credit: Gyou-Jin Cho/Sunchon National University

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

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>>

September 10, 2009

Graphite, data storage and semiconductors

Interesting release from Rice involving graphite and nanotechnology, but not the usual carbon nanotubes, graphene or graphane.

The release:

Graphitic memory techniques advance at Rice

Researchers simplify fabrication of nano storage, chip-design tools

Advances by the Rice University lab of James Tour have brought graphite’s potential as a mass data storage medium a step closer to reality and created the potential for reprogrammable gate arrays that could bring about a revolution in integrated circuit logic design.

In a paper published in the online journal ACS Nano, Tour and postdoctoral associate Alexander Sinitskii show how they’ve used industry-standard lithographic techniques to deposit 10-nanometer stripes of amorphous graphite, the carbon-based, semiconducting material commonly found in pencils, onto silicon. This facilitates the creation of potentially very dense, very stable nonvolatile memory for all kinds of digital devices.

With backing from a major manufacturer of memory chips, Tour and his team have pushed the technology forward in several ways since a paper that appeared last November first described two-terminal graphitic memory. While noting advances in other molecular computing techniques that involve nanotubes or quantum dots, he said none of those have yet proved practical in terms of fabrication.

Not so with this simple-to-deposit graphite. “We’re using chemical vapor deposition and lithography — techniques the industry understands,” said Tour, Rice’s Chao Professor of Chemistry and a professor of mechanical engineering and materials science and of computer science. “That makes this a good alternative to our previous carbon-coated nanocable devices, which perform well but are very difficult to manufacture.”

Graphite makes a good, reliable memory “bit” for reasons that aren’t yet fully understood. The lab found that running a current through a 10-atom-thick layer of graphite creates a complete break in the circuit — literally, a gap in the strip a couple of nanometers wide. Another jolt repairs the break. The process appears to be indefinitely repeatable, which provides addressable ones and zeroes, just like today’s flash memory devices but at a much denser scale.

Graphite’s other advantages were detailed in Tour’s earlier work: the ability to operate with as little as three volts, an astoundingly high on/off ratio (the amount of juice a circuit holds when it’s on, as opposed to off) and the need for only two terminals instead of three, which eliminates a lot of circuitry. It’s also impervious to a wide temperature range and radiation; this makes it suitable for deployment in space and for military uses where exposure to temperature extremes and radiation is a concern.

Tour’s graphite-forming technique is well-suited for other applications in the semiconductor industry. One result of the previous paper is a partnership between the Tour group and NuPGA (for “new programmable gate arrays”), a California company formed around the research to create a new breed of reprogrammable gate arrays that could make the design of all kinds of computer chips easier and cheaper.

The Tour lab and NuPGA, led by industry veteran Zvi Or-Bach (founder of eASIC and Chip Express), have applied for a patent based on vertical arrays of graphite embedded in “vias,” the holes in integrated circuits connecting the different layers of circuitry. When current is applied to a graphite-filled via, the graphite alternately splits and repairs itself (a process also described in the latest paper), just like it does in strip form. Essentially, it becomes an “antifuse,” the basic element of one type of field programmable gate array (FPGA), best described as a blank computer chip that uses software to rewire the hardware.

Currently, antifuse FPGAs can be programmed once. But this graphite approach could allow for the creation of FPGAs that can be reprogrammed at will. Or-Bach said graphite-based FPGAs would start out as blanks, with the graphite elements split. Programmers could “heal” the antifuses at will by applying a voltage, and split them with an even higher voltage.

Such a device would be mighty handy to computer-chip designers, who now spend many millions to create the photolithography mask sets used in chip fabrication. If the design fails, it’s back to square one.

“As a result of that, people are only hesitantly investing in new chip designs,” said Tour. “They stick with the old chip designs and make modifications. FPGAs are chips that have no specific ability, but you use software to program them by interconnecting the circuitry in different ways.”  That way, he said, fabricators don’t need expensive mask sets to try new designs.

“The No. 1 problem in the industry, and one that gives an opportunity for a company like ours, is that the cost of masks keeps moving up as people push semiconductors into future generators,” said Or-Bach. “Over the last 10 years, the cost of a mask set has multiplied almost 10 times.

“If we can really make something that will be an order of magnitude better, the markets will be happy to make use of it. That’s our challenge, and I believe the technology makes it possible for us to do that.”

The ACS Nano paper appears here: http://pubs.acs.org/doi/pdf/10.1021/nn9006225

Read more about Tour’s research of graphitic memory here: 
http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=11817

To download images, go here: http://www.rice.edu/nationalmedia/images/graphitestripes.jpg
http://www.rice.edu/nationalmedia/images/graphitestripes2.jpg
http://www.rice.edu/nationalmedia/images/vias.jpg

March 14, 2009

Nanocups to improve optics

I’ve already bloggedon this nanotech breakthrough from Rice University before, and here’s the latest news straight from the source.

The release:

Nanocups brim with potential
Light-bending metamaterial could lead to superlenses, invisibility cloaks

Researchers at Rice University have created a metamaterial that could light the way toward high-powered optics, ultra-efficient solar cells and even cloaking devices.

Naomi Halas, an award-winning pioneer in nanophotonics, and graduate student Nikolay Mirin created a material that collects light from any direction and emits it in a single direction. The material uses very tiny, cup-shaped particles called nanocups.

In a paper in the February issue of the journal Nano Letters, co-authors Halas and Mirin explain how they isolated nanocups to create light-bending nanoparticles.

In earlier research, Mirin had been trying to make a thin gold film with nano-sized holes when it occurred to him the knocked-out bits were worth investigating. Previous work on gold nanocups gave researchers a sense of their properties, but until Mirin’s revelation, nobody had found a way to lock ensembles of isolated nanocups to preserve their matching orientation.

“The truth is a lot of exciting science actually does fall in your lap by accident,” said Halas, Rice’s Stanley C. Moore Professor in Electrical and Computer Engineering and professor of chemistry and biomedical engineering. “The big breakthrough here was being able to lift the nanocups off of a structure and preserve their orientation. Then we could look specifically at the properties of these oriented nanostructures.”

Mirin’s solution involved thin layers of gold deposited from various angles onto polystyrene or latex nanoparticles that had been distributed randomly on a glass substrate. The cups that formed around the particles – and the dielectric particles themselves – were locked into an elastomer and lifted off of the substrate. “You end up with this transparent thing with structures all oriented the same way,” he said.

In other words, he had a metamaterial, a substance that gets its properties from its structure and not its composition. Halas and Mirin found their new material particularly adept at capturing light from any direction and focusing it in a single direction.

Redirecting scattered light means none of it bounces off the metamaterial back into the eye of an observer. That essentially makes the material invisible. “Ideally, one should see exactly what is behind an object,” said Mirin.

“The material should not only retransmit the color and brightness of what is behind, like squid or chameleons do, but also bend the light around, preserving the original phase information of the signal.”

Halas said the embedded nanocups are the first true three-dimensional nanoantennas, and their light-bending properties are made possible by plasmons. Electrons inside plasmonic nanoparticles resonate with input from an outside electromagnetic source in the same way a drop of water will make ripples in a pool. The particles act the same way radio antennas do, with the ability to absorb and emit electromagnetic waves that, in this case, includes visible wavelengths.

Because nanocup ensembles can focus light in a specific direction no matter where the incident light is coming, they make pretty good candidates for, say, thermal solar power. A solar panel that doesn’t have to track the sun yet focuses light into a beam that’s always on target would save a lot of money on machinery.

Solar-generated power of all kinds would benefit, said Halas. “In solar cells, about 80 percent of the light passes right through the device. And there’s a huge amount of interest in making cells as thin as possible for many reasons.”

Halas said the thinner a cell gets, the more transparent it becomes. “So ways in which you can divert light into the active region of the device can be very useful. That’s a direction that needs to be pursued,” she said.

Using nanocup metamaterial to transmit optical signals between computer chips has potential, she said, and enhanced spectroscopy and superlenses are also viable possibilities.

“We’d like to implement these into some sort of useful device,” said Halas of her team’s next steps. “We would also like to make several variations. We’re looking at the fundamental aspects of the geometry, how we can manipulate it, and how we can control it better.

“Probably the most interesting application is something we not only haven’t thought of yet, but might not be able to conceive for quite some time.”

The paper can be found at http://pubs.acs.org/doi/abs/10.1021/nl900208z?prevSearch=mirin&searchHistoryKey.

March 4, 2009

Light bending nanoparticles

Filed under: Science, Technology — Tags: , , , — David Kirkpatrick @ 3:58 pm

From KurzweilAI.net — Nanotechnology news from Rice University on light-bending nanoparticles.

Scientists Create Light-Bending Nanoparticles
PhysOrg.com, Mar. 3, 2009

Rice University researchers discovered that Cup-shaped gold nanostructures can bend light in a controllable way, acting like three-dimensional nano-antennas, Rice University researchers have discovered.

This property should prove useful in developing new optical materials and devices, such as solar cells, light attenuators, and chip-to-chip optical interconnects.

 
Read Original Article>>

February 9, 2009

Nanotech and battery efficiency

The latest news on nanotechnology and lithium-ion batteries.

The release from today:

Batteries get a boost at Rice

Researchers create hybrid nanocables to improve lithium battery technology

Need to store electricity more efficiently? Put it behind bars.

That’s essentially the finding of a team of Rice University researchers who have created hybrid carbon nanotube metal oxide arrays as electrode material that may improve the performance of lithium-ion batteries.

With battery technology high on the list of priorities in a world demanding electric cars and gadgets that last longer between charges, such innovations are key to the future. Electrochemical capacitors and fuel cells would also benefit, the researchers said.

The team from Pulickel Ajayan’s research group published a paper this week describing the proof-of-concept research in which nanotubes are grown to look – and act – like the coaxial conducting lines used in cables. The coax tubes consist of a manganese oxide shell and a highly conductive nanotube core.

“It’s a nice bit of nanoscale engineering,” said Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science.

“We’ve put in two materials – the nanotube, which is highly electrically conducting and can also absorb lithium, and the manganese oxide, which has very high capacity but poor electrical conductivity,” said Arava Leela Mohana Reddy, a Rice postdoc researcher. “But when you combine them, you get something interesting.”

That would be the ability to hold a lot of juice and transmit it efficiently. The researchers expect the number of charge/discharge cycles such batteries can handle will be greatly enhanced, even with a larger capacity.

“Although the combination of these materials has been studied as a composite electrode by several research groups, it’s the coaxial cable design of these materials that offers improved performance as electrodes for lithium batteries,” said Ajayan.

“At this point, we’re trying to engineer and modify the structures to get the best performance,” said Manikoth Shaijumon, also a Rice postdoc. The microscopic nanotubes, only a few nanometers across, can be bundled into any number of configurations. Future batteries may be thin and flexible. “And the whole idea can be transferred to a large scale as well. It is very manufacturable,” Shaijumon said.

The hybrid nanocables grown in a Rice-developed process could also eliminate the need for binders, materials used in current batteries that hold the elements together but hinder their conductivity.

 

###

 

The paper was written by Reddy, Shaijumon, doctoral student Sanketh Gowda and Ajayan. It appears in the online version of the American Chemical Society’s Nano Letters.

The project is supported by funding from the Hartley Family Foundation.

The paper can be found online at: http://tinyurl.com/dz7oe8.

November 18, 2008

Baker Institute looks to Obama for tech advancement

Filed under: Business, Politics, Technology — Tags: , , , — David Kirkpatrick @ 4:13 pm

Although the anti-science slant of GOP is much more biology-based, having Obama in office ought to help technology advacement as well. Anything is better than relying on the “magical thinking” of the religious right.

The release:

Baker Institute expert says America needs Obama leadership in technology security, advancement

The United States needs to act swiftly and sufficiently under an Obama presidency to secure the government’s technology infrastructure and to re-establish America’s standing as a leader in technology advancements, according to Christopher Bronk, a fellow in technology, society and public policy at Rice University’s Baker Institute for Public Policy.

“The sad reality is that the United States has fallen behind in the race for the next great technology discovery,” Bronk said. “India, China and a host of other countries are investing a lot of capital in technology research. I wouldn’t be surprised if the next IBM, Microsoft or Google comes out of China.”

He also warned that the United States is unprepared in computer security. Bronk said, “Our infrastructure from the top down is broken, putting America at risk for a major cyber attack and data breaches. With leadership on this issue, we can mitigate many of the problems and serve as a model for the world. 

“The government needs to go back to what it does best: invest internally on IT issues with human capital and work with academia and industry on crafting solutions rather than blindly outsourcing decisions and management that should be kept in government,” Bronk said.

He said the failure to increase funding at the National Science Foundation and the relative decline in corporate research and development is mostly to blame. “Whether it’s creating that next great technology or keeping America’s people, businesses and government safe, I would encourage President-elect Obama to not forget what government does do well: Protect us. Whether that is in the field of combat or in cyberspace, if we’re going to fight a war, it needs to be funded appropriately.”

On a side note, Bronk said that reports citing security concerns of Obama using a personal phone device for personal e-mail is unwarranted. “There are ways to keep the president-elect’s mobile device secure for e-mail and other uses. I understand the concern of those e-mails being made a public document, but don’t lay blame on security.”

Christopher Bronk:

Bronk is the Baker Institute fellow in technology, society and public policy. He previously served as a career diplomat with the United States Department of State on assignments both overseas and in Washington. His last assignment was in the Office of eDiplomacy, the department’s internal think tank on information technology, knowledge management, computer security and interagency collaboration. He also has experience in political affairs, counternarcotics, immigration and U.S. — Mexico border issues. Since arriving at Rice, Bronk has divided his attention among a number of areas, including information security, technology for immigration management, broadband policy, Web 2.0 governance and the militarization of cyberspace. He teaches classes on the intersection of computing and politics in Rice’s George R. Brown School of Engineering.

Bronk has provided commentary for a variety of news outlets, including ABC, NPR, the BBC and the Houston Chronicle. His latest research involves the political informatics of transnational terror.  Bronk has a Ph.D. from the Maxwell School of Syracuse University and a bachelor’s degree from the University of Wisconsin–Madison. He also studied international relations at Oxford University.

October 18, 2008

Buckypaper sounds like a wild tech

Filed under: Science, Technology — Tags: , , , — David Kirkpatrick @ 5:26 pm

Check out this artcle from PhysOrg. Wow.

From the link:

It’s called “buckypaper” and looks a lot like ordinary carbon paper, but don’t be fooled by the cute name or flimsy appearance. It could revolutionize the way everything from airplanes to TVs are made.

Buckypaper is 10 times lighter but potentially 500 times stronger than steel when sheets of it are stacked and pressed together to form a composite. Unlike conventional composite materials, though, it conducts electricity like copper or silicon and disperses heat like steel or brass.

“All those things are what a lot of people in nanotechnology have been working toward as sort of Holy Grails,” said Wade Adams, a scientist at Rice University.

That idea – that there is great future promise for buckypaper and other derivatives of the ultra-tiny cylinders known as carbon nanotubes – has been floated for years now. However, researchers at Florida State University say they have made important progress that may soon turn hype into reality.

Buckypaper is made from tube-shaped carbon molecules 50,000 times thinner than a human hair. Due to its unique properties, it is envisioned as a wondrous new material for light, energy-efficient aircraft and automobiles, more powerful computers, improved TV screens and many other products

October 17, 2008

Now this is research I can get my hands around …

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 12:14 am

… in a frosty 12 oz. bottle.

The release:

Better beer: college team creating anticancer brew

Rice students enter ‘BioBeer’ in synthetic biology’s iGEM contest

College students often spend their free time thinking about beer, but a group of Rice University students are taking it to the next level. They’re using genetic engineering to create beer that contains resveratrol, a chemical in wine that’s been shown to reduce cancer and heart disease in lab animals.

Rice’s “BioBeer” will be entered in the International Genetically Engineered Machine (iGEM) competition Nov. 8-9 in Cambridge, Mass. It’s the world’s largest synthetic biology competition, a contest where teams use a standard toolkit of DNA building blocks — think genetic LEGO blocks — to create living organisms that do odd things.

Notable past iGEM creations include sheets of bacteria that behave like photographic film and bacteria that smell like mint while they’re growing but like bananas when they stop growing. Rice’s student-led iGEM team — the Rice BiOWLogists — are returning for a third year. Their entry last year, a bacterial virus that fought antibiotic resistance, was well-received but finished out of the prize running.

“After last year’s contest, we were sitting around talking about what we’d do this year,” said junior Taylor Stevenson. “(Graduate student) Peter Nguyen made a joke about putting resveratrol into beer, but none of us took it seriously.”

But when the team began looking in earnest for a new project this spring, they discovered a good bit of published literature about modifying yeast with resveratrol-related genes. When they looked further, they found two detailed accounts by teams that had attacked both halves of the metabolic problem independently.

“That was when we said, ‘You know, we could actually do this,'” said junior Thomas Segall-Shapiro.

Ironically, most of the team’s undergraduate members aren’t old enough to legally drink beer. But the reality is that with less than a month to go until the competition, the team has yet to brew a drop. All their work to date has gone into creating a genetically modified strain of yeast that will ferment beer and produce resveratrol at the same time. While the team does plan to brew a few test batches in coming weeks, these will contain some unappetizing chemical “markers” that will be needed for the experiments.

“There’s no way anyone’s drinking any of this until we get rid of that, not to mention that there’s only one genetically modified strain of yeast that’s ever been approved for use in beer, period,” said Segall-Shapiro. “In short, it will be a long time before anybody consumes any of this.”

So why would someone want to make beer with resveratrol in the first place? It’s a naturally occurring compound that some studies have found to have anti-inflammatory, anticancer and cardiovascular benefits for mice and other animals. While it’s still unclear if humans enjoy the same benefits, resveratrol is already sold as a health supplement, and some believe it could play a role in the “French paradox,” the seemingly contradictory observation that the French suffer from relatively low rates of heart disease despite having a diet that’s rich in saturated fats.

“I have seen some studies where it’s been shown to activate the same proteins that are known to play a role in extending the life span of lab animals that are kept on low-calorie diets,” said junior David Ouyang.

Ouyang said the team is working with a strain of yeast that’s used commercially to make wheat beer. They got a sample of the yeast from Houston’s Saint Arnold Brewing Company, and they are modifying it with two sets of genes. The first set allows the yeast to metabolize sugars and excrete an intermediate chemical that the second set can later convert into resveratrol.

“One set of genes gets you from A to B, and the other gets you from B to C,” said Stevenson. “We’ve already created a strain that has the B-to-C genes, but our genes for the A-to-B part are still on order.”

With some luck and hard work, the team said it will finish the full A-to-C yeast in time to get some data before heading to Cambridge. But even if they don’t have this final piece of the puzzle, they’re confident they’ll have plenty of data from other experiments and computer models.

Faculty adviser Jonathan Silberg said the iGEM competition provides a unique educational experience for undergraduates.

“In terms of education value, the great thing about synthetic biology research is that it stimulates undergraduate creativity and gives them an opportunity to work collaboratively at an early stage of their science and engineering education,” said Silberg, assistant professor of biochemistry and cell biology. “While students work collaboratively in other undergraduate research endeavors, they typically are not given the pie-in-the-sky opportunity to pursue their own ideas.”

Regardless of how the BiOWLogists fare with BioBeer, they are already looking ahead to next year. Team members recently filed the necessary paperwork to create the Rice Synthetic Biology Club. Ouyang said the official recognition will help ensure Rice’s annual presence at iGEM, even after the current team members graduate.

The other 2008 Rice BiOWLogists are sophomore Selim Sheikh, junior Arielle Layman, senior Sarah Duke, graduate student Justin Judd and faculty advisers Silberg, George Bennett and Beth Beason, all of Biochemistry and Cell Biology; Oleg Igoshin and Junghae Suh, both of Bioengineering; and Ken Cox of Chemical and Biomolecular Engineering.

Update — I sent an email to the media contact asking how many inquiries have come in regarding this release.

Here’s the response from David Ruth, “Since issuing the news release yesterday afternoon we’ve received numerous media inquiries, including calls from high-profile newspapers and magazines. Thanks for your note.”