Nanoclast iconNanoclast

New Form of Graphene Opens up Applications in Thermal Conductivity for Electronics

Much has been made of how graphene’s lack of an inherent band gap holds it back in electronics applications.

But there are a couple of flaws in this argument. For one, not all would-be applications require the band gap seen in silicon-based materials. And what if there is actually more than one type of graphene?

Researchers at the University of Calfornia Riverside, in collaboration with researchers from The University of Texas at Austin, The University of Texas at Dallas and Xiamen University in China have in fact developed a new form of graphene whose purpose makes its lack of a bandgap irrelevant.

The researchers, led by Aelxander Balandin, a professor of electrical engineering at UC Riverside, and Professor Rodney S. Ruoff of UT Austin, have isotopically engineered graphene so it that has concentrations of 99.99 percent 12C (carbon) as opposed to the naturally occurring graphene that is found in concentrations of 98.9 percent 12C and 1.1 percent 13C.

What difference does 1 percent make? In a paper ("Thermal conductivity of isotopically modified graphene") published in the 8 Jan online version of the journal Nature Materials, the team reported that the slight variation in graphene's composition that they were able to achieve using chemical vapor deposition yielded a material that had remarkable heat dissipation qualities.  They say that the isotopically engineered graphene should should be useful in heat removal applications in a number of electronics applications as well as in photovoltaics.

“The important finding is the possibility of a strong enhancement of thermal conduction properties of isotopically pure graphene without substantial alteration of electrical, optical and other physical properties,” said Balandin in the UC Riverside press release. “Isotopically pure graphene can become an excellent choice for many practical applications provided that the cost of the material is kept under control.”

Importantly, the proposed applications do not call for graphene to replace silicon in the integrated circuit of the future, but for its use in the interconnects and thermal spreaders within computers or in transparent electrodes in photovoltaics.

Still, it's important to remember that while application proposals are intriguing at this stage, this is basic research. As Balandin remarks: “The experimental data on heat conduction in isotopically engineered graphene is also crucially important for developing an accurate theory of thermal conductivity in graphene and other two-dimensional crystals.”

Graphene Nanoribbons Get Super Computerized

About a year-and-a-half ago, researchers at EMPA and the University of Bern in Switzerland along with those from the Max Planck Institute for Polymer Research devised a method for growing from the bottom up a ribbons of graphene only a few nanometers wide.

In the time that has elapsed since then, researchers around the world have started to examine the material, and now scientists at Rensselaer Polytechnic Institute have focused one of the world’s most powerful supercomputers on it to uncover its properties.

What the Rensselaer researchers discovered was graphene nanoribbons when segmented take on various surface structures dubbed “nanowiggles” and that these structures produce different magnetic and conductive properties.

It is expected that the findings, which were published in the journal Physical Review Letters in a paper titled “Emergence of Atypical Properties in Assembled Graphene Nanoribbons”,  should enable others to pick characteristics of the graphene nanostructure and thereby customize the material to meet the requirements of a particular application.

“Graphene nanomaterials have plenty of nice properties, but to date it has been very difficult to build defect-free graphene nanostructures. So these hard-to-reproduce nanostructures created a near insurmountable barrier between innovation and the market,” said Vincent Meunier, the Gail and Jeffrey L. Kodosky ’70 Constellation Professor of Physics, Information Technology, and Entrepreneurship at Rensselaer in a press release from the Institute covering the research. “The advantage of graphene nanowiggles is that they can easily and quickly be produced very long and clean.”

One of the intriguing bits was that in the researchers’ computational analysis of the nanowiggles they discovered that they produce highly varied bandgaps. According to Meunier, this should allow for the tuning of the bandgap of the material to fit a certain application.

"We have created a roadmap that can allow for nanomaterials to be easily built and customized for applications from photovoltaics to semiconductors and, importantly, spintronics,” said Meunier.

Why is Russia Hot on Molecular Nanotech and the US Not?

Proponents of molecular nanotechnology (MNT) often point to the backroom politics back at the turn of the century that relegated ideas of nanobots and tabletop factories to the margins of nanotechnology’s development in the United States. Instead what we saw was the rise of material science on the nanoscale become the darling of research funding. Or so the story goes.

But not to worry, the US is not the only country on the planet. The father of MNT (or, if you prefer, advanced, atomically precise nanotechnology), Eric Drexler, recently discovered this when he attended Rusnanotech 2011 and received an extremely warm reception to the ideas of MNT.

I say, well done. It’s about time. Just because the US government decided that it would make more sense to fund an evolution of technology that could show benefits in a few short years rather than a few short decades, doesn’t mean that funding for that line of research doesn’t exist.

I have often said that if the MNT community wanted to get funding, then they should propose physical experiments and go out and secure the funding as Philip Moriarty did. With successful physical experimentation--as opposed to merely successful computer modeling--this would open the way to new experiments and new funding.

Perhaps an inch-by-inch method was not what the MNT community wanted to hear when the distances that needed to be covered were so great, but it certainly seems better than sitting down and complaining about one's predicament.

But as you look at this story of Russia’s interest in MNT the question inevitably arises: Why would Russia be so keen on MNT and the US so uninterested?

Backroom deals notwithstanding, the forms of government in the US and Russia are quite different.

I recently heard it argued that if “no taxation without representation” is true, then so is its inverse: no representation without taxation.

In countries where the leadership is funded by the exploitation of the local natural resources (like fossil fuels), it is unnecessary for that leadership to levy taxes on its citizens for its revenues and therefore doesn’t need to engage in the messy business of giving them any representation. The leadership can just do whatever they want without fear of retribution at the ballot box.

Russia does have some form of elections but it doesn’t appear to be so sensitive to the electorate that the idea of spending $10 billion of the electorate’s tax money and having little to show for it except some far-off promises would make much of a difference to their political careers.

I would suggest to MNT proponents that they should go around to the countries of the world that have a glut of cash and managed to get that money without tax revenues and propose research projects that have gone unfunded to date. Time to start drawing up those physical experiments.

With Science and Patience, Lawsuits against Nanotechnology Are Avoidable

Just before the holiday week, I read the discouraging news that a consumer group had filed a lawsuit against the Food & Drug Administration (FDA) regarding risks from the use of nanomaterials in products.

It seems that NGOs like the International Center for Technology Assessment (ICTA), inspired by their half-informed self-righteousness, somehow believe that lawsuits against the US government (the defense costs taxpayers will have to pay) is somehow helpful in either protecting consumers or determining the toxicity of nanomaterials that make up part of the material matrix of highly regulated products.

I mean the argument appears ridiculous on its surface. Basically, the ICTA believes that the FDA has been “unlawfully” delaying its decision on the safety of products that contain nanomaterials after the ICTA and other NGOs filed a petition in 2006.

How to explain the time it takes to get this sorted? Let’s see, with the elements contained in the periodic table we know the toxicity of the materials contained within it and the toxicity of the compounds when you mix these elements together. But what is being asked at this point is to reinvent the periodic table so that elements that have long-been considered benign need to be considered potentially toxic in their nanoscale form. Does any fair-minded person believe this constitutes heel dragging or an unlawful delay?

I must say I really enjoy how the NGOs always refer to a growing body of evidence about the toxicity of nanomaterials in products. They are masters this kind of rhetorical flourish, except when the tables are turned.

Despite my cynical appreciation of their manipulation of the media, I challenge them to show me one conclusive study that shows a product containing nanomaterials in a matrix has harmed anybody. You know, a tennis racquet or bicycle frame containing carbon nanotubes that causes sickness, or, dare I say, their favorite target: sunscreens that make people sick.

Just to anticipate their response, this is not the same as a nanomaterial in its free-floating form in which some nanomaterials have reportedly caused harm to workers. While this particular study I linked to here should be a cause of concern and a spur to further research, it has been revealed to have serious flaws in its science, and, most importantly, does not refer to nanomaterials that have been fixed into a larger material matrix.

My concern here is that all this bluster and self-satisfied finger pointing doesn’t manage to get us one step closer to determining whether nanomaterials when fixed into a material matrix are any more likely to be toxic to consumers than the bromine and PVC in your computer.

I want to know. And I would prefer that our tax dollars be spent on conducting that research to find out rather than being used to defend one of our government agencies from a lawsuit that doesn’t appear to have legs, but has kept the press occupied.

The Second Annual Nanoclast Awards

Last year I set out with some trepidation on the long-term project of maintaining an annual Nanoclast Awards.

We have arrived at the second year of this project and I haven’t yet abandoned it.

In the inaugural event I established three prize categories: Best Advancement in Nanomaterials, Best Advancement in Microscopy and the Most Annoying Nano-related Story of the Year.

 I was never quite married to these categories so I am going to change them somewhat this time around. We will again see Best Advancement in Nanomaterials, but this time Best Nano-Enabled Device and Nanotech Hero of the Year will join them.

Best Advancement in Nanomaterials

Without further ado, on to the nominees for Best Advancement in Nanomaterials: For this category, I would like to exercise some symmetry (and avoid graphene taking all the nominations) and have the nominees come from quantum dots, graphene and carbon nanotubes.

The first nominee will come from carbon nanotubes. It in fact involves two breakthroughs from one researcher and her team’s attempts to use carbon nanotubes in flexible electronics.

Zhenan Bao and her research team at Stanford University devised a method by which they could spray single-walled carbon nanotubes (SWNTs) onto a thin layer of silcone and create a stretchable pressure sensor, that could act like an artificial skin.

While this bit of the research was impressive it was perhaps the method they developed for sorting the SWNTs that may have an even broader impact. By combining these two pieces of research together, it has been nominated in the carbon nanotube category for Best Advancement in Nanomaterials.

For quantum dots it has been encouraging to see more work coming out for their application to solar cells. While there have been others that have furthered the use of quantum dots in photovoltaics, Edward H. Sargent and his research team at the University of Toronto have really stood out.

Sargent and his collaborators have pushed colloidal quantum dot (CQD) solar cell energy conversion efficiency up to 6 percent. Sargent’s aim in this work is ambitious: to “break the existing compromise between performance and cost.”

For graphene it has been another bumper crop year. Typically, graphene grabs headlines for the work being done in applying it to electronics. But graphene is showing its worth in other applications, especially in areas where its inherent lack of a bandgap doesn’t create such a liability.

While perhaps humble in comparison to using graphene to maintain Moore’s Law, research at the University of Colorado, Boulder have discovered that graphene has unexpected adhesion characteristics that could lead to some quickly applicable industrial uses, such as natural gas processing or water purification.

Obviously, the nanomaterials category is the most competitive and as a result some truly groundbreaking work may have inadvertently been omitted, but the winner this year from our three nominees goes to: Edward H. Sargent and his research team at the University of Toronto for their work in improving the energy conversion rate of colloidal quantum dots.

Best Nano-Enabled Device

Now on to our second category, Best Nano-Enabled Device.

Our first nominee comes from the Nanoscale Science and Engineering Center at the University of California, Berkeley and involves their work in developing a graphene-based optical modulator.

What is so noteworthy about this work is how easily it can be adapted into CMOS manufacturing.

The second nominee could also win “My Biggest Regret of the Year” award, if there was one. I rather flippantly dismissed this work mainly because of a bad headline, and I was fairly and emphatically criticized. But however you look at it, the work is significant. Researchers at the Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) nodes at the University of Sydney and Macquarie University have developed a device that slows down light enough so as to generate individual pairs of photons. This device will likely enable faster information speeds and data that is impossible to hack.

As one of the comments made clear in the original story: “It is undoubtedly enabled by nanotechnology - we need control of dimensions to scales as small as a nanometer or so to get these devices to work the way we really want them to - and the key dimensions are indeed of the order of 100 nm.” I agree and stand corrected.

The third and final nominee for this category goes to the work of Charles Lieber and his team at Harvard University for using nanowires to create the for the first time programmable logic “tiles”.

Lieber remained realistic about the possibilities of the devices, citing their slow processing speed, but remarked that because of their high density and low power consumption they could be attractive for a “controller for some microelectromechanical device.”

The winner for this year’s Nanoclast Award for best Nano-enabled device goes to Dr Chunle Xiong of the University of Sydney and Macquarie University's Associate Professor Michael Steel along with the rest of their CUDOS colleagues.

Nanotech Hero of the Year

 Now on to our third and final category: Nanotech Hero of the Year.

This year I was grateful to meet in person a number of nanotech heroes face-to-face, namely Michael Grätzel, Heinrich Rohrer  and Gerd Binnig.

But these personal heroes of mine are not what I intend for this category no matter how great their accomplishments. Instead I want to highlight an individual who has taken a stand within the field that runs contrary to established beliefs this year.

For this category, I have only one nominee and winner: Professor Mike Kelly at Cambridge University for Advanced Photonics and Electronics, who has made himself a bit of a pariah I would have to think for his contention that nanotechnology will be limited to three nanometers.

From my original blog entry: “The main thrust of Kelly’s argument is one that is not altogether that radical, which is that you may be able to fabricate one-off structures that have dimensions below 3nm but you won’t be able to duplicate that in a full-scale manufacturing process.”

It is a debatable point and may ultimately be proven to be false, but it should and likely will govern how nanotechnology research is conducted and as a result we will surely have better work as a result.

What's Old Is New Again in Nanotechnology

Last week while watching the BBC News, I saw a brief text report that said how a nanoparticle coating had been invented that could make clothes clean themselves just by exposing them to the sun.

I found this brief report shocking not because of how inventive or amazing a breakthrough it was, but because to my knowledge this invention occurred some years back.

The use of titanium dioxide in the form of nanoparticles that are used with textiles to create a “self-cleaning” mechanism is not new. The characteristic of TiO2 as a photo catalyst could hardly be described as an invention.

Even the humble Nano&Me, which I contributed to nearly three years ago and was aimed at those absolutely uninformed about nanotechnology, talks about reports of TiO2 used as a self-cleaning agent in textiles.

So, was this just invented as the BBC seems to indicate, or not? We have to say, no.

But maybe if we go to the ACS journal Applied Materials and Interfaces in which the research was published we can sort out how there is this confusion.

Just by reading the first sentence of the abstract, we get it. This is not just cotton treated with TiO2 but cotton treated with a mix of silver iodide (Agl) along with Nitrogen (N)-TiO2. This combination increased the photocatalytic activities of the material.

So, this is what I find so infuriating about coverage of nanotechnology. Couldn’t someone (besides me) have said that researchers had found a way of improving the photocatalytic performance of TiO2 in textiles so as to make their self-cleaning properties X times better than previous methods?

Again, it seems the answer is no.

The Nanotechnology and GMO Link Repeated…Again

There are two main groups hard at work trying to establish similarities between nanotechnology and genetically modified organisms (GMOs): the press and NGOs.

In the case of the press, their motivation is quite simple. It’s about selling papers and establishing or re-establishing, as the case may be, the particular media outlet’s hard-hitting investigative journalism credentials.

For NGOs the explanation is somewhat more obscure simply because we can’t see the traces of greed on it. Instead what we get with NGOs is what one might call, in psychological terms, transference.

What they are really angry about involves wars and their loss of privacy, but, most importantly, the threat of big business doing something for profit that puts them somehow at risk. Nanotechnology just happens to be a good scapegoat for them to address those fears and concerns.

So in line with this, we get from the venerable Atlantic a kind of amalgam of these two in an abysmal piece entitled “Is Nanotechnology the New GMO?" I say amalgam because on the one hand it is written for the mainstream press, but on the other hand it is authored by someone who is not just a journalist but a professor of food with book titles to her credit such as: "Food Politics: How the Food Industry Influences Nutrition and Health." I don't think I am extrapolating too much by thinking that the title draws comparisons to the sentiments of your typical NGO.

Anyway, let’s start with the question in the title of this piece. If I may offer a question in response: In what way could nanotechnology be like GMO? Of course, at the very end of the article we discover it’s the usual idea that nanotechnology has been somehow thrust upon people and as soon as they find out about it, they will reject it—in some regions of the world.

As worn thin as this idea is in the mainstream media, the general public keeps on dismissing it as a source of concern. No harm in beating a dead horse, I guess, though some may feel it to be a bit unseemly.

But there are other shockers in this piece. For instance, we get the unequivocal statement: “Nanotechnology science is new, and the industry is unregulated.”

Oh dear, where to begin? First off, nanotechnology is not an industry and never will be an industry any more than silicon is an industry.  Nanotechnology enables products. All of these products must meet consumer guidelines for safety, i.e. they are highly regulated.

Now if you want to discuss regulations of nanomaterials and not a “nanotechnology industry” (which one would expect to include AFMs and STMs), then that’s an interesting discussion. But even there the so-called “industry” has been working under the regulations that have governed the chemical industry for decades. To say that the use of these nanomaterials is unregulated is just misleading, if not ignorant.

Since the author is a supposed expert on the food industry, she gets to cleverly play on the emotional responses of the readers here by discussing nanotechnology in relation to food.

Of course, the food one eats triggers a highly emotional response, like discovering what’s really in your hot dog. So playing on speculation and fear mongering really gets you a long way on that subject.

Despite the reporter’s expertise on the food industry, what I would like to know is what the reporter was thinking when she states: “Food companies often don't know whether or not they are using these materials.”

What?! The food industry is made up all sorts of scientists devising processes and ingredients for producing food. If you think for one minute that nobody along the entire food production chain knows exactly what is in the food they are selling to the public, you have been misinformed.

What we seem to have here in this piece is what was revealed as the real cause of the Friends of the Earth’s concerns about nanotechnology in food: “What it comes down to, I’d recommend that consumers veer away from processed foods.”

A preaching nanny hardly seems to be helpful on this issue.

 

 

A Little Nanotechnology Discipline, Please!

Mainstream media often makes a hash out of reporting nanotechnology.

The latest on the long list of how perfectly respectable journalists typically turn in the most misleading copy on nanotechnology comes from the International Herald Tribune (IHT).

In the very first sentence we get: “the world of nanotechnology involves shrinking things down to a whole new level ie [sic] where things are a billion times smaller than the world of meters that we live in.”

Of course, you can imagine a reader of this thinking that nanotechnology involves “shrinking things down” not unlike the 1960s movie “Fantastic Voyage” to where white blood cells attack your miniaturized submarine.

And what does it mean: “a billion times smaller than the world we live in.”? Cells, molecules, atoms and subatomic particles all inhabit the world we live in.

But if that was bad, the next paragraph loses all connections to any kind of rational thought: “But, at present, we cannot really think about basic concepts like width, breadth, depth and height or even bigger problems like poverty and global warming on a scale which is 1,000 times smaller than a fly’s eye – they all lose meaning on the nanoscale.”

I am simply dumbfounded. Even when I can’t understand what they have written I can guess at what they might be thinking. But this really stretches me to the limits of my imagination.

As depressing as this is, I have become inured over the years to reading some pretty rough stuff from journalists when it comes to nanotechnology. But what really sent me over the edge on this one was the rather irresponsible manner in which the expert, Dr Abdul Qadeer from the Federal Urdu University of Arts, Science and Technology, presents the future of nanotechnology.

“In the future, there is a possibility to make nanorobots,” Qadeer is quoted as saying in the IHT piece. “These can be injected into our bodies to carry out repairs.”

Is it any wonder then that the journalist starts his piece with the idea of “shrinking things” straight from Fantastic Voyage imagery?

It’s one thing for journalists not to do their homework on an assignment, but it’s quite another when the experts advising them lead them astray.

Carbon Nanotube-Enabled Flexible Backplanes Promise Smart Device Ubiquity

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a material that uses carbon nanotubes to create a flexible backplane for an artificial electronic skin (e-skin).

“With our solution-based processing technology, we have produced mechanically flexible and stretchable active-matrix backplanes, based on fully passivated and highly uniform arrays of thin film transistors made from single walled carbon nanotubes that evenly cover areas of approximately 56 square centimeters,” says Ali Javey, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a professor of electrical engineering and computer science at the University of California (UC) Berkeley in Berkeley Lab press release. “This technology, in combination with inkjet printing of metal contacts, should provide lithography-free fabrication of low-cost flexible and stretchable electronics in the future.”

It seems carbon nanotubes and artificial skin is becoming a popular research area as researchers at nearby Stanford University also looked at how carbon nanotubes could be used in flexible electronics and started demonstrating the usefulness of the method with an artificial skin.

Javey and his colleagues have published their work in the ACS journal Nano Letters in a paper entitled “Carbon Nanotube Active-Matrix Backplanes for Conformal Electronics and Sensors”.

Curiously the researchers bemoan the general problem that has existed in this are of flexible electronics of not being able to attain a pure single-walled carbon nanotube (SWNT) solution to create your flexible electronic devices. I say curious because Zhenan Bao—the same researcher at Stanford who developed the artificial skin—also developed in cooperation with researchers from the University of California Davis a method by which to come up with the exact mix of SWNTs you want.

In the Berkeley Lab press release it is made clear that the researchers used “a SWNT solution enriched to be 99-percent semiconductor tubes”, but it doesn’t indicate how they were able to get that level of purity. Maybe they can give Bao a shout out and try and use her method.

In any case, it will be interesting to see if the two research groups can move this initial work that uses  artificial skin as a demonstration of the methods into broader uses for furthering the development of flexible electronics.

US Nanotechnology Initiative Responds to Presidential Committee's Recommendations

Approximately 20 months after the President's Council of Advisors on Science and Technology’s (PCAST) biennial review of the National Nanotechnology Initiative (NNI) in which it offered some suggestions on how to improve the US’s competitiveness in nanotechnology, the various representatives of the NNI provided their response.

The webcast of this November 2 hearing can be viewed from here.  If you prefer a brief written summary of the four speakers, you can find that here in a report from the American Institute of Physics.  All of the materials from the meeting, including the presentations, can be found here.

My take on the PCAST recommendations is that they wanted to start seeing more commercial products from the $14 billion that has been invested in nanotech research over the last 10 years, and they wanted the issue of environmental, health and safety (EHS)…shall we say…adequately addressed.

The answer for these calls has been to increase the number of public/private partnerships and improving tech transfer mechanisms to shorten the timescale of moving from fundamental research to commercial products.

That sounds fine, but the test of time will determine whether these measures can actually make an impact in the commercial development of nanotech research.

As far as EHS issue, we are told in the presentation that $500 million has been invested thus far into addressing this issue. I am not sure that a little over 3.5% of the overall nanotech research budget is enough to address the EHS concerns surrounding nanotechnology, or, more importantly, satisfy the groups who have placed themselves in opposition to nanotechnology and called on a moratorium of all research.

Whatever your opinion is of the PCAST recommendations to the NNI, or the NNI’s response to those suggestions, you have to be impressed with the transparent way that the US government operates in its nanotechnology initiative. For someone like myself who spends some time in looking into the nanotech initiatives of other countries, it is impressive.

Advertisement

Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
Contributor
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
Load More