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Hyperbolic Reporting on Nanotechnology in Food Wreaks Havoc

This past summer Nature published an article outlining some of the causes for the recent bombing attacks on nanotechnology labs. At the time, I suggested on this blog that most of the article scanned about right except for one notable omission: poor reporting on nanotechnology in the mainstream press. 

One of the clearest indications of how this bad journalism has misinformed the public was when the terrorist group “Individuals Tending Toward the Savage,” which attacked a nanotech lab in Mexico, made public its raison d’etre. In it they demonstrated a truly distorted idea of what nanotechnology is and what scientists working on the nansoscale are doing. In their letter they demonstrated the misapprehension that the nanotechnology of today threatens us with the prospect of “grey goo” as tiny nanobots eat the world and leave behind a waste product of goo.

I laid at least part of the blame for this terrorist group confusing science with science fiction at the feet of mainstream journalists, who, not being familiar with the field, mistake Michael Crichton’s Prey with Eric Drexler’s Engines of Creation. It’s probably not fair to say they are confused; it’s more likely the case they have never heard of the latter.

The perfect example of this comes in an article appearing on the website for the local PBS TV station in Los Angeles (KCET). In it the author, explains that Crichton’s Prey is “actually turning out to be more prescient than pessimistic.” The author based his conclusion on article he read in a publication called “E-The Environmental Magazine”.

While that article is filled with a bit more hyperbole and conjecture presented as cold-hard fact than I care for, at least it has an inkling of what a nanoparticle is. But the writer for KCET doesn’t even get that. He believes “nanoparticles” are just another way of saying, “small robots that can move about your body as they please.”

 I am sorry, but nanoparticles are not small robots wandering around in our bodies delivering nutrients, or “attacking from the insides.” Let’s just start there.

Now onto the more reality-based arguments presented in both the E Magazine and KCET articles.  We get this in the E Magazine article: “There is no doubt that nanoparticles are in the food supply and have been for years.” As proof of this statement, the author references research that found carbon nanoparticles in “caramelized sugar, including bread and corn flakes”.

If you have ever heated sugar in a chemistry class you probably recall that carbon, oxygen and hydrogen in the sugar separate. The oxygen and hydrogen burn off leaving carbon behind—probably in nanoscale particles. Is this some deliberate attempt by unscrupulous food company scientists to put nanoparticles (oops, I mean nanobots) into the food supply? Probably not. But if the E Magazine editor wants real proof of nanoparticles in our food, she need only turn to mayonnaise, which is an emulsion of lipids and proteins that are on the nanoscale. I wonder if over 250 years of mankind eating mayonnaise passes the long-term-health-risk test?

Two years ago, the UK government's House of Lords Science and Technology Committee decided they were going to get to the bottom of this nanotechnology-in-food issue. They put together a panel of experts, interviewed experts from all aspects of the issue and concluded that they couldn’t really say to what extent nanotechnology is used in our food.

But I am sure that the author at E Magazine understands the issue better than some UK government committee (it’s likely just some conspiracy anyway to cover up the entire issue) and the reporter can come to conclusions that were not possible for the experts.

One clear conclusion we can make from all of this, however, is that the reporter at E Magazine, in an attempt to heighten the fear factor, got another reporter to believe that nanoscale robots were circulating through our body doing some good, but also possibly some unknown harm. Now there is a much wider swath of the general public that believes nanoscientists are producing nanobots that will result in some scenario from the novel Prey.

We’ve already witnessed the damage, maiming and destruction that one small group of people can wreak when they don’t really understand what nanotechnology is. At present that violence far exceeds any harm that nanotechnology has perpetrated upon anyone. Maybe we should be hyping just how careless and misguided the coverage of the subject is and the harm that may be doing.

4-D Nanowire Transistor Takes Shape of a Christmas Tree

Eighteen-months ago, Intel announced with great enthusiasm its three-dimensional (3-D) transistor, dubbed Tri-Gate.  Of course, regular readers of Spectrum have known for years that 3-D transistors were going to be with us sooner or later.

Once you’ve gone from 2-D to 3-D, the next logical step is 4-D, right? Well at least that's the progression that researchers at Purdue and Harvard University want to make. The joint research team has developed a transistor consisting of three nanowires made out of indium-gallium-arsenide instead of silicon. The resulting transistor’s combination of speed and stacking capabilities have led the researchers to refer to it as ‘4-D’.

“It's a preview of things to come in the semiconductor industry," said Peide "Peter" Ye, a professor of electrical and computer engineering at Purdue University, in a press release. "A one-story house can hold so many people, but more floors, more people, and it's the same thing with transistors. Stacking them results in more current and much faster operation for high-speed computing. This adds a whole new dimension, so I call them 4-D."

The advance couldn't be more timely, at least insofar as the transistor is shaped a bit like a Christmas tree—the three nanowires are progressively smaller, resulting in tapered cross section silhouette you'd more likely see at Rockefeller Center than on a chip. (Unfortunately no images of the transistor will be available until 8 December.)

More than the design of the transistor, the real breakthrough for the so-called 4-D transistors was the coating of the nanowires with a new dielectric layer material made from a combination of lanthanum aluminate and aluminum oxide. This new dielectric layer allowed the researchers to use indium-gallium-arsenide, dubbed III-V semiconductor materials, in place of silicon.

Combining elements from group III of the periodic table, including indium and gallium, with those from group V, such as arsenic, has been suggested as a replacement for silicon since the 1960s. The attraction of these hybrid materials is that they can move electrons around much faster than silicon can.

One hiccup in the use of these III-V semiconductors has been reducing the dimensions of the transistor’s gate. The Purdue-Harvard team claims that their indium-gallium-arsenide transistors have 20-nanometer gates, a milestone, according to Ye.

The research will be presented at the IEEE’s International Electron Device Meeting in San Francisco, CA next week in two separate papers.

Innovative Nanopatterning Technique Looks to Anti-Counterfeiting Applications

Earlier this year, researchers at IBM Zurich developed a process in which they used the surface tension of water to manipulate gold nanorods and arrange them into specific patterns.

The technique, which was published in the Wiley journal Advanced Functional Materials ("Self-Assembly: Oriented Assembly of Gold Nanorods on the Single-Particle Level"), allowed the researchers to arrange the nanorods into a pattern resembling the German Ampelmännchen, which is used in Berlin’s crosswalk signals to direct pedestrians when to cross a street.

While that was a nifty demonstration, it didn’t reveal commercial applications. Now, however, the research team led by Dr. Heiko Wolf believes that the technique could be used in anti-counterfeiting efforts.

"In addition to using nanorods, we can also create patterns using florescent spheres which emit red, green and blue,” says Heiko in an IBM press release. “What makes this particularly interesting is that they add another level of security, in that the order of the colors in which they arrange themselves is completely random. So not even I could replicate the pattern. We call it a physically uncloanable function or PUF."

Heiko further describes the technology and its anti-counterfeiting capabilities in the video below:

While I can understand the IBM research team’s enthusiasm for their newly-found application possibilities, there are a couple of issues that may limit commercialization.

The IBM press release presents this work as a first for anti-counterfeiting with nanotechnology, but there are already existing techniques with similar applications. SingularID, (now part of Bilcare Research) use nanomagnets to create a suite of tools that can be used for detecting counterfeits. The patterns generated with Bilcare’s technique are also completely random and can’t be reproduced. What makes that technology stand out is that it’s not just a material but an entire product that can be bought to combat counterfeiting. There's always room for another player in the market, but IBM will have to prove that their method has additional advantages. 

Secondly, when I heard Heiko explain, “All you need is an optical microscope to see the pattern,” I immediately thought that it sounded impractical. While a nanoscientist might think analyzing a product with an optical microscope is no big deal, it’s hard to picture a port authority official sitting down with one to check and see if the Swiss watches are what they claim to be.

The IBM Zurich team have found a very good way to create nanopatterns with nanoparticles using a directed self-assembly technique, but it may still be in search of a worthy application outside of anti-counterfeiting.

Innovative Nanofabrication Technique Produces Semiconductors without a Substrate

If you stepped up and suggested that eliminating the substrate was the future of semiconductor manufacturing, nine times out of 10 (or 10 out of 10) you would be dismissed with a wave of the hand. That’s not too different than the initial reactions Lars Samuelson of Lund University in Sweden received when he presented that possibility to his colleagues.

“When I first suggested the idea of getting rid of the substrate, people around me said ‘you’re out of your mind, Lars; that would never work,'” Samuelson relates in a release describing his latest research. But it did work and the process for doing it, which was published in the journal Nature ("Continuous gas-phase synthesis of nanowires with tunable properties"),  looks like it could reach the commercial stage in applications for solar cells in as little as two to four years.

The process consists of putting freely suspended gold nanoparticles in a gas flow. These gold nanoparticles serve as a substrate on which semiconductor nanowires can grow.

Research in the area of growing nanowires with “seed” particles (metal nanoparticles) in a gas flow has already enjoyed some breakthroughs this year. In February, researchers at MIT demonstrated that by controlling the amount of gas you could actually change the properties of the resulting nanowires.

However, the Lund University research team still saw that the field of fabricating semiconductor nanowires lacked a method by which nanowires could be mass-produced “with perfect crystallinity, reproducible and controlled dimensions and material composition, and low cost.”

So Samuelson and his colleagues experimented with a process they dubbed “aerotaxy”--a name based on the process known as epitaxy, in which a crystal layer is grown on crystal substrate. Aerotaxy is essentially an aerosol-based growth method that proved successful in continuously producing nanowires with controlled dimensions. The trick to getting it to work properly was carefully controlling the temperature, the timing of the process, along with the dimensions of the seed particles—in this case, the gold nanoparticles.

“In addition, the process is not only extremely quick, it is also continuous. Traditional manufacture of substrates is batch-based and is therefore much more time-consuming,” adds Samuelson in the release.

The research team has gone so far as to actually build a prototype manufacturing system consisting of a series of ovens that will cure the nanowires to create variants such as p-n diodes. With this focus on engineering the fabrication techniques, the researchers seem to be really pushing for a solar cell prototype in two years.

Collodial Semiconductors Challenge Amorphous Silicon

Amorphous silicon has been the “king of the hill” when it comes to thin, fast, and flexible semiconductors, but researchers at the University of Pennsylvania believe they have knocked the king off his throne and maybe right into the past.

The U Penn research team, led by doctoral students David Kim and Yuming Lai along with Professor Cherie Kagan, have used cadmium selenide nanocrystals (which are proving themselves useful in a number of areas)  to deliver devices that can move electrons 22 times faster than in amorphous silicon.

Cadmium selenide nanocrystals are within a class of colloidal semiconductor nanocrystals that have been found effective for making thin-film field-effect transistors. Essentially taking the form of ink, these colloidal nanocrystals have tantalized researchers looking to create inexpensive thin-film electronics. But until this most recent research they had not been demonstrated for use in the high-performance field-effect transistors needed in large-area integrated circuits.

The Penn research, which was published in the journal Nature Communications (“Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors”), may have found a way to achieve these high-performance large-area integrated circuits.

The researchers started with a flexible polymer on which they used a masking technique to stencil one level of electrodes for the circuit. Another area on the polymer was stenciled off for a conducting gold that would later serve as the electrical connection to the upper levels of the circuit. After putting down an insulating aluminum oxide layer, a spincoating deposition technique was used to deposit a 30-nanometer layer of nanocrystals on top.

What might be the main distinguishing factor between this technique and previous methods using colloidal semiconductor nanocrystals  was the use of a new ligand. These ligands extend out from the surface of the nanocrystals and aid conductivity of the nanocrystals as they are packed tightly together.

“There have been a lot of electron transport studies on cadmium selenide, but until recently we haven’t been able to get good performance out of them,” says Kim in a press release. “The new aspect of our research was that we used ligands that we can translate very easily onto the flexible plastic; other ligands are so caustic that the plastic actually melts.”

While the nanocrystal-based devices that the researchers developed are giving amorphous silicon a run for the money in terms of electron mobility, it doesn’t seem that the researchers are targeting amorphous silicon’s main application of flat-panel displays. Instead they envision these flexible and easy-to-produce circuits in pervasive sensors used in either security or biomedical applications.

Newly Developed Live Nanoscale Imaging Technique Promises Improvement in Li-ion Batteries

Much of the nanotechnology-related work going on today for improving Lithium-ion (Li-ion) batteries has focused on developing nanostructured silicon to replace graphite in the anodes of the next generation Li-ion batteries.

While this work has been encouraging, another line of research has taken a different tack. Instead of just replacing the graphite in the anodes, researchers have sought to determine why the degradation of Li-ion batteries’ storage capacity occurs in the first place.

Two years ago, I covered work conducted at Ohio State University in conjunction with both Oak Ridge National Laboratory and the National Institute of Standards and Technology that employed every microscopy tool researchers could get their hands on in the search for nanoscale phenomena that would cause this degradation. The results showed that the material from which the electrodes in Li-ion batteries are made coarsen over time; the lithium ions that need to go between the positively and negatively charged electrodes become increasingly unavailable for charge transfer.

Now researchers at the U.S. Department of Energy’s Brookhaven National Laboratory have developed a new imaging technique that allows them to observe lithium-ion reactions in real time with at the nanoscale precision.

Critical to the new imaging technique is transmission electron microscopy (TEM), which has been used to fabricate the “world’s smallest” battery. In the Brookhaven work, which was published in the journal Nature Communications (“Tracking lithium transport and electrochemical reactions in nanoparticles”), the TEM is modified with an in-situ electrochemical cell that can operate inside the TEM. This novel design gives researchers the combination of live imaging found with in-situ techniques and the spatial resolution and nanoscale precision of TEM.

The design of the modified TEM may be novel, but it’s not overly complex. “The entire setup for the in-situ TEM measurements was assembled from commercially available parts and was simple to implement," said Brookhaven Lab physicist and lead author Feng Wang in a press release. "We expect to see a widespread use of this technique to study a variety of high-energy electrodes in the near future,” says Wang.

The new imaging technique allowed the researchers to observe the lithium ion reaction that occurs across iron fluoride (FeF2) nanoparticles. They watched the lithium ions move quickly across the surface of the nanoparticles and then observed the compounds being broken down into different regions in a layer-by-layer process—all in real time. The Brookhaven team saw that the lithium-ion reaction leaves in its wake a trail of new molecules.

“Although many questions remain regarding the true mechanisms behind this conversion reaction, we now have a much more detailed understanding of electron and lithium transport in lithium-ion batteries,” said Brookhaven physicist and study coauthor Jason Graetz in the release. “Future studies will focus on the charge reaction in an attempt to gain new insights into the degradation over time that plagues most electrodes, allowing for longer lifetimes in the next generation of energy storage devices.”

Block Copolymers Lead to Five-fold Increase of Disk Drive Storage Capacity

Earlier this year nanoscientists in Ireland took their first steps towards realizing the promise of block copolymers  for next generation computing. Their research, which included scientists from both the University of Wisconsin and Intel, developed a method for fabricating large-area arrays of silicon nanowires through the directed self-assembly (DSA) of block copolymer nanopatterns.

Now researchers at the University of Texas Austin in collaboration with the disk drive company HGST have exploited the DSA characteristics of block copolymers to create a new type of disk drive with up to five times the storage capacity of today’s models.

The new research, which was published in the journal Science (“Polarity-Switching Top Coats Enable Orientation of Sub–10-nm Block Copolymer Domains”),  was not only able to push the boundaries of storage capacity, it created a method that is well matched with today’s manufacturing processes.

While the method’s compatibility with current high-throughput techniques is critical for it to be adopted into commercial applications, it is the extraordinary speed at which the block copolymers self assemble that has amazed even the researchers.

“I am kind of amazed that our students have been able to do what they’ve done,” says co-author C. Grant Willson, a professor of chemistry at U Texas Austin, in a press release. “When we started, for instance, I was hoping that we could get the processing time under 48 hours. We’re now down to about 30 seconds. I’m not even sure how it is possible to do it that fast. It doesn’t seem reasonable, but once in a while you get lucky.”

In addition to its speed and compatibility with current manufacturing techniques, the newly developed method addresses a real need in computing. Data storage on disk drives is approaching its limits. In the past, we've always stored more by packing the magnetic dots that make up the data on disk drives closer together. But the industry now has reached about a terabit of data per square inch (2.54 cm) of disk. If you bring them much closer, the magnetic fields of each dot begin to interfere with each other and data can be corrupted.

This use of block copolymers makes it possible to make the disk so that there are no magnetic fields between the dots but they are still isolated from one another. This means you can push the dots closer together without any magnetic fields interfering with the dots and corrupting the data.

The key to the process the U Texas researchers developed is a spin-on top coat that neutralizes surface energy at the top interface of a block copolymer film. This allows the polymers to orient themselves to the plane of the disk with just heat.

“The patterns of super small dots can now self-assemble in vertical or perpendicular patterns at smaller dimensions than ever before,”  saysThomas Albrecht, manager of patterned media technology at HGST, in the release. “That makes them easier to etch into the surface of a master plate for nanoimprinting, which is exactly what we need to make patterned media for higher capacity disk drives.”

As with the research coming out of Ireland earlier this year, this work was conducted in close collaboration with industry, suggesting that commercial applications of the technology are a real possibility in a fairly short time—much shorter than typically seen in this kind of lab research.

Sunlight and Nanoparticles Make Steam Without Boiling Water

According to some sources, steam-driven turbines still account for between 80 and 90 percent of the electricity generated in the world.  Of course, the method for producing that steam can vary from nuclear power to burning fossil fuels.

Now researchers at Rice University believe that they have found a completely new way for generating steam by placing light-absorbing nanoparticles in water and focusing sunlight on the water so that steam is produced without actually boiling the water.

In this new method not only is it not necessary to boil the water, but the Rice researchers have also demonstrated that steam can be produced in water that remains near the freezing point with this sunlight/nanoparticle combination.  According to the researchers, the steam is produced at very high efficiency in which 80 to 90 percent of the energy absorbed from the sun is actually converted to steam.

When these figures are translated into the energy conversion measurements used for photovoltaics it has an overall energy efficiency of 24 percent, significantly higher than photovoltaics that typically measure around 15 percent energy conversion efficiency.

A video demonstrating and describing the technology can be seen below:

The research, which was published in the journal ACS Nano (“Solar Vapor Generation Enabled by Nanoparticles") , made use of a range of materials including metallic and carbon nanoparticles. The key feature for all of them was that they needed to absorb light. When dispersed into water, these nanoparticles direct most of the energy into creating steam rather than heating up the water. 

“We’re going from heating water on the macro scale to heating it at the nanoscale,” says Naomi Halas, the lead scientist on the project, in a press release. “Our particles are very small — even smaller than a wavelength of light — which means they have an extremely small surface area to dissipate heat. This intense heating allows us to generate steam locally, right at the surface of the particle, and the idea of generating steam locally is really counterintuitive.”

While the technology is a tantalizing alternative to the way most industrial steam is produced in large boilers, the first prototypes of the technology have taken on a more modest scale.

Funded by a Grand Challenges grant from the Bill and Melinda Gates Foundation, the research team built a small-scale system for treating human waste in areas without sewer systems or electricity. The Rice team have also created a system based on the technology that could sterilize medical and dental instruments in places lacking electricity.

A small-is-beautiful approach to this technology may be the way to proceed initially, but the big hope certainly has to be that it could make large-scale electricity production cheaper and more efficient.

A Twist and Some Wax Turns Carbon Nanotubes into Super Muscles

Carbon nanotubes have already been demonstrated to be a useful material in the development of artificial muscles. But an international team of researchers led by the University of Texas at Dallas has discovered that if you twist carbon nanotubes into a yarn and infuse them with paraffin wax their capabilities as artificial muscles become staggering.

The researchers claim that the wax-infused muscles can lift 100 000 times their own weight and produce 85 times more mechanical power than natural muscle of equivalent size.

“The artificial muscles that we’ve developed can provide large, ultrafast contractions to lift weights that are 200 times heavier than possible for a natural muscle of the same size,” says Dr. Ray Baughman, team leader, Robert A. Welch Professor of Chemistry and director of the Alan G. MacDiarmid NanoTech Institute at UT Dallas in a press release. “While we are excited about near-term applications possibilities, these artificial muscles are presently unsuitable for directly replacing muscles in the human body.”

You can see Baughman further describe the carbon nanotube-based muscles in the video below:

While Baughman concedes that replacing artificial muscles in humans is out of the application list for this material at the moment, he does believe that it could be used in “robots, catheters for minimally invasive surgery, micromotors, mixers for microfluidic circuits, tunable optical systems, microvalves, positioners, and even toys.”

Baughman further believes that the material can make its way into marketable uses fairly quickly. He notes in the release: “The remarkable performance of our yarn muscle and our present ability to fabricate kilometer-length yarns suggest the feasibility of early commercialization as small actuators comprising centimeter-scale yarn length. The more difficult challenge is in upscaling our single-yarn actuators to large actuators in which hundreds or thousands of individual yarn muscles operate in parallel.”

Whether Baughman can tackle that next challenge remains to be seen, but the research, which was published in the journal Science (“Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles"), is impressive in its elegant simplicity.

The combination of twisting carbon nanotubes into a yarn and infusing them with wax made it possible to simply add a bit of electrical charge to the material to get the wax to expand and then the yarn volume to increase, causing the yarn to shorten. This volume increasing and length decreasing is directly related to the twisting of the carbon nanotube yarn.

In operation, when the wax-filled yarn is heated electrically it untwists, but when the heating is stopped the yarn winds back up. What is remarkable is how fast this twisting and untwisting occurs. The researchers claim that yarn can rotate a paddle that is attached to the yarn at 11 500 revolutions per minute. Perhaps more importantly, it can repeat this cycle more than 2 million times.

Another attractive feature of the material is that fact that it can be treated like a textile. So it could be sewn or woven into clothing to react to outside environmental factors such as heat (a fireman’s coat is given an as an example in the video) and actuate (like a muscle) a change to the textile’s porosity. This change in porosity could provide thermal protection, or chemical protection in the presence of poisonous substances.

Paper and Scissors Key in Latest Development of Nanofluidics

When one recalls that graphene was first produced by placing scotch tape on top of the graphite found in pencils and then pulling the tape off, it may not sound so strange that the next breakthrough in nanofluidic devices may come from using paper and scissors.

Two researchers at Northwestern University have discovered that if you stack up layers of graphene on top of one another it creates a flexible paper-like material that forms tens of thousands of nanoscale channels between the layers.  In keeping with the school supplies theme, the researchers further discovered that they could cut the paper-like material into any shape they wished with a pair of scissors.

“In a way, we were surprised that these nanochannels actually worked, because creating the device was so easy,” said Jiaxing Huang, quoted in a university press release. Huang, a Junior Professor in Materials and Manufacturing, who conducted the research with postdoctoral fellow Kalyan Raidongia, said, “No one had thought about the space between sheet-like materials before. Using the space as a flow channel was a wild idea. We ran our experiment at least 10 times to be sure we were right.”

The material could potentially have applications in batteries, water purification, harvesting energy and DNA sorting. While listing a range of applications for lab technologies is always a fairly easy matter, this material stands out in these application areas because of how cheaply and easily it is produced.

Typically nanofluidic devices require slow and expensive lithography techniques to carve out the channels. But this technique lends itself to the building of massive arrays of nanochannels simply by staking sheets of graphene oxide (GO) on top of one another. To create more nanochannels, simply stack more layers on top of each other.

The research, which was published in the Journal of the American Chemical Society (“Nanofluidic Ion Transport through Reconstructed Layered Materials’), demonstrated a working device using the material by cutting a piece of the GO paper into a centimeter-long rectangle. Huang and Raidongia covered the paper in a polymer. They then drilled either end of the rectangle to fashion holes in which an electrolyte solution was placed.

In tests, the researchers discovered that the rectangle conducted a higher than normal amount of current, whether it was laid out flat or bent.

The next step is to test the nanoscale properties of papier-mâché. Just kidding—but maybe someone should try it.

 

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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.

 
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Dexter Johnson
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Rachel Courtland
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