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Stretching of Graphene Could Launch the Age of "Straintronics"

The publication ElectroIQ has an article on recent research coming out of Lawrence Berkeley National Laboratory that has shown that a three-point stretch of graphene creates nanobubbles in which the electrons segregate into quantized energy levels instead of occupying energy bands.

The research, which was originally published in the July 30th edition of the journal Sciencehas revealed that the electrons within the nanobubbles mimic the energy levels they would have if they were moving in circles in the presence of a strong magnetic field as high as 300 tesla. 

According to Michael Crommie, professor of physics at UC Berkeley and a faculty researcher at LBNL, in the ElectroIQ article this discovery makes it possible to control how electrons move in graaphene and thereby manipulate the material’s electronic properties.

“By controlling where the electrons bunch up and at what energy, you could cause them to move more easily or less easily through graphene, in effect, controlling their conductivity, optical or microwave properties,” says Crommie in the article. “Control of electron movement is the most essential part of any electronic device."

As one might imagine, an experiment to stretch a piece of graphen was hardly planned. Instead this discovery was serendipitous after a UC Berkeley postdoctoral researcher and several students in Crommie’s lab grew graphene on a platinum crystal. Because the carbon atoms in graphene have a hexagonal pattern and the platinum has a triangular crystal structure they don’t line up and a strain pattern is created as though it were being pulled from three different directions.

While the findings may have been serendipitous, the results were predicted in carbon nanotubes as far back as 1997.

Now we can start using the term “straintronics” which involves, according to Crommie, “…the idea of using mechanical deformations in graphene to engineer its behavior for different electronic device applications."

Nanomagnets May Mitigate the Need for Dialysis in Removing Pathogens from Blood

Last week, Nanowerk’s Spotlight piece covered recent research in which Swiss researchers demonstrated that they could remove metal ions, steroid drugs and proteins from blood by using nanomagnets.

The nanomagnets are basically carbon-coated iron carbide at the nanoscale (an average diameter of 30 nanometers) and are functionalized with linker molecules that attract the target material in the blood.

The work comes out of the Functional Materials Laboratory (FML) that was founded in 2004 by Prof. Wendelin J. Stark at ETH Zurich (Swiss Federal Institute of Technology Zurich).

One of Stark’s PhD students, Inge Hermann, was the first author on a paper in the journal Small entitled “Blood Purification Using Functionalized Core/Shell Nanomagnets”.

According to Inge in the Nanowerk piece, the system is capable of selectively removing toxins or pathogens from whole blood within minutes. Among the clearest advantages of this process over other blood purification techniques, such as dialysis and plasma filtration, is its ability to get to substances of different masses and dimensions and it doesn’t suffer from filter cut offs or slow pore diffusion in membranes.

“By using magnetic metal nanomagnets carrying target-specific ligands, we showed that blood purification at a nano- to pico-molar scale is possible," says Prof. Stark in the Nanowerk article.

It seems the researchers have high hopes for the commercial prospects of the process. An ETH spin-out company has already been formed called Turbobeads that will commercialize at least parts of the metal nanomagnet technology.

Carbon Nanotubes Enable Pumpless Liquid Cooling System for Computers

Researchers at Purdue University have developed a new design employing carbon nanotubes and small copper spheres that wicks water passively towards hot electronics that could meet the challenges brought on by increasing frequency speeds in chips.

The problem of overheating electronics is well-documented and in the past the issue has been addressed with bigger and bigger fans. But with chip features shrinking below 50 nanometers the fan solution is just not cutting it.

The Purdue researchers, led by Suresh V. Garimella, came up with a design that uses water as the coolant liquid and transfers the water to an ultrathin thermal ground plane. The design naturally pushes the water through obviating the need for a pump and through the use of microfluidic design is able to boil the water fully, which allows the wicking away of more heat.

One of the keys to the design was creating pore sizes that were smaller than previous sintered designs. While achieving the smaller pore size the researchers had to overcome the problem of frictional resistance on the liquid that would come with more pores (the smaller they are the more of them there are). It’s here that the carbon nanotubes came into play as the researchers used 50-nm copper coated carbon nanotubes to make the small pores.

 

This is not the first time that Purdue researchers have worked with carbon nanotubes to dissipate heat in chips. A few years back they were looking at growing millions of carbon nanotubes on a chip like grass to dissipate the heat generated from chips, and showed promise in better conducting heat in passively cooled systems such as cellphones than thermal greases now commonly used. 

A Defense Advanced Research Projects Agency (DARPA) grant is funding this mos recent research and the Purdue researchers are collaborating with Raytheon, Thermacore Inc. and Georgia Tech on the project.

Ask Not for Whom the Bell Tolls in Nanotech

Tim Harper has been covering what he describes as the “Death of UK Nanotech” over at his TNTLog and I hope it serves as a cautionary tale to other regions of the world on the pitfalls of certain nanotechnology development strategies.

Harper quotes a recent assessment of UK Science Minister David Willets who commented that it would be “most unlikely” that the UK’s 24 nanotech centers will still be open in 18 months.

The problem appears to be one of politics. In an effort to allow every region of England to be part of the economic transformative power of “the next big thing”, they built 24 separate nanotech centers rather than focusing their resources into one or two large labs, like France did with their Grenoble innovation cluster.

While the US nanotechnology initiative has been far less diluted in its focusing of resources, just taking into account just the dimensions of the two countries, there is still that troubling catering to constituencies that you get in representative democracies.

Evidence of this was seen at the President’s Council on Science and Technology (PCAST) meeting to examine innovation frameworks for nanotechnology in which the story was related of how the National Science Foundation with just a couple of million dollars set aside was looking to develop new instrumentation technologies, and splitting that money between 13 bids. The likely result being that not one of the projects will be able to progress very far in developing any new instruments but it may satisfy some notion of spreading the wealth.

Since TNTLog first started covering this story both Frogheart and TNTLog have noted that this closing down of at least some of the 24 nanotech centers may be old news and its current discussion being just another political ploy.

That said, whether the demise of these research facilities is new or old news there are lessons to be learned from their unraveling.

Nano-enabled Wound Dressing Discerns between Good and Bad Bacteria

When it comes to our health there are bacteria that are beneficial, and there are also bacteria that are quite detrimental. Some UK researchers wanted to address this problem of why some bacteria are pathogenic and some are not. The process of answering that question led them to demonstrating how a nanocapsule system can be a “nano-Trojan horse” for combating only harmful bacteria  in infections while leaving 'friendly' bacteria untouched.

The work, which was conducted at the Department of Chemistry at the University of Bath and originally published in the Journal of the American Chemical Society, is ultimately a proposal for a nanocapsule system that administers antimicrobial treatments only in the presence of pathogenic bacteria.

 

As one of the researchers, Toby Jenkins,  explains in the Nanowerk Spotlight piece linked to above it was discerning the property that makes some bacteria pathogenic that made it possible to figure out a way of destroying them. “Basically, we have found a way so that we can use the property that makes some (not all) bacteria pathogenic by presenting them with capsules which bacterial secretion toxins attack (as if they are healthy tissue). Inside the capsules is an antimicrobial or a dye," says Jenkins.

This possibility of having a “smart” wound dressing that would kill harmful bacteria while ignoring the billions of harmless bacteria would be of critical importance to the treatment of burn victims.

"Our advanced wound dressing dressing will work by releasing antibiotics from nanocapsules triggered by the presence of disease-causing pathogenic bacteria, which will target treatment before the infection takes hold," Jenkins explains. "The dressing will also change color when the antibiotic is released, alerting healthcare professionals that there is infection in the wound. This is an important step in treating burns patients, particularly children, where infections can lead to toxic shock syndrome, a potentially fatal condition."

White House Announces Opening of Portal for Public Input on Nanotechnology Strategy

Everyone has a blog, including the White House, where it was announced this week that the President’s Office of Science and Technology Policy (OSTP)  has made available the National Nanotechnology Initiative (NNI) Strategy Portal where it will be possible to submit your thoughts and ideas on how to advance nanotechnology’s development. The portal is described as on online event and will only be open from July 13th to August 15th, so be sure to make your recommendations soon.

I was initially skeptical of this proposal to get the input of the public when it was first presented because they made it seem they wanted ideas on new application areas. However, when it became clear that OSTP’s aim was to re-think innovation frameworks I was easily turned around since this has always been the problem area.

But even when the focus became clear it seemed that the highly sophisticated recommendations were not really discussed in a rigorous way. That could have just been how it seemed during the meeting and perhaps afterwards the suggestions were given more serious consideration.

This latest blog entry from the White House, however, has some interesting little ticks. Most notable to me is that there are these two generations of nanotechnology applications. One is enabled by mere nanomaterials and the other newer generation by something else, which is never quite identified.

“President Obama’s Strategy for American Innovation highlights the promise of nanotechnology to transform multiple industries: capturing and storing clean energy, developing next-generation computer chips, early detection of diseases, smart anti-cancer therapeutics that deliver drugs only to tumor cells, and enabling all-new approaches to a wide range of manufacturing activities, among many other examples. While the commercial impact of nanotechnology to date has been limited primarily to nanomaterials applied to a range of consumer goods from healthcare to textiles, automotive composites and industrial coatings, nanotechnology innovation is poised to accelerate dramatically. Among the most compelling recent examples are solar cells leveraging nanotechnology to increase efficiency and reduce costs and bullet-proof, flexible carbon nanotube-based armor.”

I would hereby like to inform the White House that all the examples of newer, better application areas they have identified for nanotechnology will be made possible through nanomaterials (or as they say, “limited to nanomaterials”).

I can’t get past the idea that they just might be thinking or imagining molecular manufacturing as the means by which the next generation of applications for nanotechnology will be realized. Granted, there’s nothing specific that I can point to for this conclusion, except that they see current applications being “limited” by just using nanomaterials. What do they expect to enable the next generation, fairy dust?

Nano-enabled Coating Makes Aircraft Invisible

No, we're not talking about a Wonder Woman-type of invisible plane, but rather one that becomes very difficult to detect with radar.

The Israel-based Ynetnews is reporting that an Israeli company called Nanoflight has successfully run a test on dummy missiles that were painted with the nano-enabled coating and have shown that radar could not pick them up as missiles.

The YnetNews article rather brutally points out that painting an aircraft with this nanocoating is far cheaper than buying a $5 billion US-made stealth aircraft. Of course, it should also be noted that one sale of a $5 billion aircraft employs a large number of aeronautical engineers, and the high price tag also makes it far more difficult for others to purchase the technology and possess the ability to sneak up on an enemy as well.

The nanocoating achieves its radar trickery by absorbing the radio waves emitted by the radar and scattering them as heat energy enough so that when the radar gets the bounced back signal it is not regular enough to indicate an object.

It seems that nano-enabled paint is the way towards commercial success in nanotechnology as I discovered at London conference a couple of years ago in which a number of projects producing exotic nanomaterials were trotted out but only one company that actually made a nano-enabled product: a paint.

Nanoflight appears pretty far along in its development process as well. A spokesman for Nanoflight, Eli Shaldag, is quoted in the article indicating that the company is in the second stage of its development process after which they will be able to produce the coating in larger quantities.

The company also sees an opportunity to use the material on the soldiers to make them invisible to infrared and night-vision goggles.

One-step Process for Creating Nanocircuits from Graphene Reported

We have seen this year IBM labs reporting on their method for giving graphene a band gap and then exceeding their own transistor speed record. This has been the way with graphene the last few years, one ground-breaking report after another.

So we’ve almost come to expect some news on the graphene front and last month we weren’t disappointed when a team of researchers reported in Science that they had developed a one-step process that uses a heated atomic force microscope (AFM) tip to tune the topographical and electrical properties of reduced graphene oxide for graphene-based electronics.

The researchers from Georgia Tech, the U.S. Naval Research Laboratory and the University of Illinois at Urbana-Champaign were partly inspired by the understanding that on the macroscale when graphene oxide is put into furnaces its properties can be changed from being an insulating material to a ore conductive graphene-like material. With this knowledge the researchers discovered that reduced graphene oxide started to become more conductive at 130 degrees Celsius.

In an article available on the Navy Research Laboratory’s website, Georgia Institute of Technology physicist Elisa Riedo notes, "We've shown that by locally heating insulating graphene oxide, both the flakes and epitaxial varieties, with an atomic force microscope tip, we can write nanowires with dimensions down to 12 nanometers. And we can tune their electronic properties to be up to four orders of magnitude more conductive. We've seen no sign of tip wear or sample tearing,"

According to William P. King, associate professor in the Mechanical Science and Engineering department at the University of Illinois at Urbana-Champaign, the research stands out for three reasons: 1) It can be accomplished in one step 2) They believe all graphene will behave this way (changing from an insulator to a conductor when heat is applied) 3) The writing process with the heated AFM tip can be accomplished at a high rate.

It seems graphene is continuing its astonishing run of breakthroughs. Maybe if it stays in the fields of electronics and photonics and away from tennis racquets and bicycles it can avoid the fate of carbon nanotubes and fall victim to the rants of NGOs, who like to cite inconclusive research as evidence for banning their use.

Nanoparticles Enable Remote Control of Living Organism's Behavior

Let me settle you down a little after the headline above. We’re only talking about the ability to have remote control over the behavior of worms here, and merely getting them to recoil at that.

But it is true that researchers at the University of Buffalo have managed to attach nanoparticles to the cell membranes of worms and then heat those nanoparticles up by exposing them to a magnetic field. The heat then opens up calcium ion channels in the cells, which in turn activates neurons, causing the worms to recoil (see video below).

Now before some NGOs get the wrong end of the stick on this one and start dreaming up dark scenarios of nanotechnology controlling the minds of both man and beast, the purpose of this research is not only to better understand the signaling networks controlling animal behavior but also for developing better cancer treatments and diabetes therapies. The idea being that if the nanoparticles can be made to target certain cells (like cancer cells) it may be possible to heat them up with the magnetic field and kill them.

As attractive as this specific targeting of cancer cells sounds, I am always a bit leery of this kind of treatment after reading George Whitesides’ succinct point on this subject “Cancer cells are abnormal cells, but they’re still us." 

 

Nanostructured Materials Could End the Need for the Dreaded Root Canal

Yesterday I urged that we start using new examples of nanotechnology applications when we are discussing the impact of nanotechnology.

While I am sure we would like to hear how nanotechnology has finally made possible a quantum computer, or that there are actually today little nanorobots circulating through our bloodstream curing us of diseases.

Unfortunately I cannot report to you today on anything like these examples. But if you’re like me and you have had a root canal in your life, and you now live in fear that you may have to undergo that medically sanctioned torture session again, I have good news.

It seems a team of European researchers have developed a nano-scale film that can be coated with a hormone that is used to fight inflammation and found when they put the film onto cells that make up dental pulp it not only reduced inflammation but also encouraged new cell growth.

Now as my dentist explained my root canal to me, the decay of the tooth had gone so deep that it had gone into the pulp of the tooth. If he had simply put a filling in the tooth, the pulp would be forever exposed causing nearly constant pain from the nerves. The solution has been to kill every last nerve in the tooth—the fun part of the root canal.

With this nano-structured mechanism, which was originally reported in the American Chemical Society’s ACS Nano Journal you won’t need to kill the tooth, just revitalize it. 

But in the publication cited above where I first read of this development they wonder whether this is just another expensive procedure that dentists will foist upon us. No doubt it will be, but it sounds as though it would be a good deal more pleasant than killing all the nerves in your tooth.

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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
 
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Rachel Courtland
Associate Editor, IEEE Spectrum
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