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E-nosy Phone Sniffs Out Danger

In the sometimes baffling array of proposed applications for nanotechnology in mobile phones,  we have a new addition with which your mobile phone can detect harmful, airborne substances.

The nanotechnology developed by the University of California (UC) Riverside researchers, led by Nosang Myung, professor and chair of the Department of Chemical and Environmental Engineering, uses nanowires made with functionalized carbon nanotubes in a sensor array to detect dangerous substances in a portable device.

While these proposed applications for mobile phones using nanotechnology are often as much marketing spin as real-world, commercial possibilities, in this case it appears that Riverside, CA-based Innovation Economy Corporation (IE Corp) has plans to commercialize the research. IE Corp is handling the commercialization through the start-up it created and funded, Nano Engineering Applications, Inc.

Nonetheless once again the mobile phone tie-in seems as though it might just be a bit of a marketing ploy. Developed using functionalized carbon nanotubes, the sensor has a broad range of applications from agriculture—where it would detect concentrations of pesticides—to military applications for detecting chemical warfare agents.

All of these are worthwhile applications, but I suppose if you want any chance of getting in the mainstream press, you have to couch your technology in terms of people’s smart phone. Detecting pesticides just doesn’t have the same appeal.

In any case, a mobile phone that can detect dangerous airborne substances is similar to the recent research out of Princeton and Tufts Universities in which a graphene nanosensor could be placed on your teeth for detecting dangerous bacteria.  It's not clear whether the UC Riverside researchers and their commercial partner IE Corp will continue to purse the portable health monitoring aspect of the technology, but it should keep the technology in the press while they pursue the various other applications.

Getting a Handle on the EU’s Definition of Nanomaterials

Last year, I covered some of the European Union's (EU) machinations in trying to arrive at a definition for nanotechnology. The EU ultimately published a definition in October last year.

There was a fair amount of surprise at some aspects of the definition, in particular its inclusion of not only manufactured nanoparticles but also the natural and incidental varieties.  This made the definition of nanomaterials so broad that industries that may never had given a second thought to nanotechnology found that they too were swept up into this regulatory framework.

The UK-based Nanosight, whose nanoparticle measurement instruments I covered back in 2007,  decided to offer a webinar that would try to bring some clarity to a definition that seemed to lack it.

In the webinar, Jeremy Warren, CEO of Nanosight, expresses his initial dismay at finding that the EU was including both natural and incidental nanoparticles in its definition for nanomaterials.

“We’ve met people recently who work on the legal side within large chemical organizations, who up until October last year didn’t know anything about nanotechnology and suddenly they’re going to be caught within legislation, which is quite a shock to them,” says Warren in the webinar.

Warren put the question of why the definition was made so broad to Dr. Denis Koltsov, a leading international expert in nanotechnology legislation and control. According to Koltsov, it seems that it was just impossible to determine whether a nanoparticle that had found its way into a nanomaterial matrix was deliberately manufactured or was a naturally occurring nanoparticle. In other words, since a regulator can’t differentiate between the various origins of the nanoparticles they just included them all.

You don’t have to extrapolate too much to conclude that companies that have been making things for years—maybe decades—without the slightest inkling that nature had put nanoparticles into their products are now part of this regulation. It got even more complicated in February of this year when the French government issued Decree # 2012-232, which ordered that anybody producing or transporting these nanomaterials in amounts of 100 grams or more would have to make a report to the French government.

While this webinar’s aim was to clarify the EU nanomaterial definition—which it largely succeeds in doing—I think more than anything I found its clarifications alarming. I joked back in October that the EU had succeeded in turning the idea of a definition on its head and offered something that broadened the definition of a nanomaterial to the nearly infinite. But now it appears that governments are now going to take this absence of a definition as an opportunity to place an entirely new layer of regulations on products and industries that seem remote from the world of nanomaterials. I don’t think it’s so funny any more.

Does Lifecycle Analysis Make Sense for Nanotechnology?

Last week, at the International Symposium on Assessing the Economic Impact of Nanotechnology held in Washington, D.C., researchers from the Georgia Institute of Technology presented a paper about using lifecycle analysis to gauge the impact of nanotechnology.

In their presentation, Philip Shapira and Jan Youtie emphasized that any assessment of nanotechnology’s impact—economic or otherwise—must take into account the full lifecycle of the product.

It seems sensible to perform a lifecycle assessment to determine how nanotechnology will add or subtract from our lives (and it rounds out the myriad other attempts at measuring its impact). But as the researchers themselves concede, it's extremely difficult to assess and make forecasts about nanotechnology, because it underlies so many different industries.

“Compared to information technology and biotechnology, for example, nanotechnology has more of the characteristics of a general technology such as the development of electric power,” said Youtie, director of policy research services at Georgia Tech’s Enterprise Innovation Institute. “That makes it difficult to analyze the value of products and processes that are enabled by the technology.”

I couldn’t agree more and it’s a point myself and others have been making for years, initially to widespread skepticism: nanotechnology is not an industry; it’s an enabling technology. If that is understood, it begs the question why continue to assess it as though it were a monolithic entity, or condemn it as one?

I think the answer is hidden in the press release for this new report when Youtie comments: “Scientists, policy-makers and other observers have found that some of the promise of prior rounds of technology was limited by not anticipating and considering societal concerns prior to the introduction of new products. For nanotechnology, it is vital that these issues are being considered even during the research and development stage, before products hit the market in significant quantities.”

Because we now have the social science capability to do this sort of thing, it seems like we're willing to apply it to a field that defies quantification of any kind.

I'm also nonplussed by another of the researcher's observations. Youtie implies that nanotechnology began with large companies and is now migrating toward an ever increasing number of small companies. I suppose a statement like this probably should be couched in all sorts of definitions of terms, which might color one’s interpretation of what it was intended to mean, but to me it seems that the trend has been almost the opposite of this.

Sure, the IBMs of the world did have the research money to develop the key tools that enabled us to work on the nanoscale. But I remember back in 2001-2003 that there were a lot of small companies that discovered that they could produce a nanomaterial and believed that this somehow would miraculously constitute a business. They soon discovered that large chemical companies could quickly produce the same material in bulk and had the supply chain connections to make sure that the material got into products. As a result, we have seen a number of small companies that were initially exhilarated they could produce carbon nanotubes in their garage get swept up into the great consolidation of nanomaterials companies.

But let’s get back to the primary point of the paper, which seems to be that we need to not only look at the great things nanotechnology can enable but also at the costs it creates. This echoes one of the most cogent arguments that the Friends of the Earth (FoE) have raised thus far. Essentially, the FoE points out that nanotechnology has not yet delivered on its claims to enable cheap solar, hydrogen and wind power, but even if it could, the energy used to create the nanomaterials would result in a net energy loss.

In an example of how quickly things change in the field of nanotechnology, a week after I covered the FoE’s report I reported on research from MIT that demonstrated a process for producing carbon nanotubes that reduced emissions of harmful byproducts by at least ten-fold and could cut energy use in half. One week you have a cogent argument, and the next you’re behind the times.

While it may be difficult to predict nanotechnology's impact without conducting lifecycle analysis, trying to include those lifecycle considerations will be far more difficult, and make their accuracy short-lived.

Image: Georgia Tech Photo (Gary Meek)

Graphene Nanosensor Tattooed to Teeth Detects Bacteria

A couple of years ago I covered research into developing a nanomaterial that could end the need for root canals. I took some criticism at the time for suggesting in that blog that root canals were unpleasant. So, despite some reluctance on my part to cover dental-related nanotechnologies, let's look once again at the latest nanotechnology being used with teeth.

The technology involves a nanosensor made out of graphene that can detect bacteria in our mouths when the sensor is in a sense tattooed to our teeth. Oddly, it seems that the bacteria that the nanosensor detects is not the Streptococcus mutans bacteria that is the principal cause of tooth decay.

While the research, which was initially published in the journal Nature Communications, may not combat tooth decay, it holds some promise as method for on-body health monitoring. The researchers from Tufts University and Princeton University have developed a method for placing wireless graphene nanosensors onto biomaterials via silk absorption.

“In our paper, we demonstrate that graphene can be printed onto water-soluble silk, says Manu S Mannoor, a graduate student at Princeton University and the paper’s first author. “This in turn permits intimate biotransfer and direct interfacing of graphene nanosensors with a variety of substrates including biological tissues and hospital IV bags to provide in situ monitoring and detection of bacterial contamination and infection."

The key to the technology seems to be the use of silk thin films. "First, we printed graphene nanosensors onto water-soluble silk thin-film substrates,” explains Mannoor in the Nanowerk piece. “The graphene is then contacted by interdigitated electrodes, which are simultaneously patterned with an inductive coil antenna. Finally, the graphene/electrode/silk hybrid structure is transferred to biomaterials such as tooth enamel or tissue, followed by functionalization with bifunctional graphene–AMP biorecognition moeities."

The researchers expect that this technology could serve as a first-generation platform of in situ monitoring for bacterial contamination in environments ranging from hospital sanitation to food safety analysis.

This new nanosensor may not alert you to the buildup of bacteria that would cause tooth decay, but it might be of interest those who like to decorate their teeth and be alerted to other types of bacteria.

Image: McAlpine Group, Princeton University

Molecular Motor Coupled to High Sensitivity Nanopore Promises Cheap DNA Sequencing

Lately we have been covering some of the recent developments in “nanopore sequencing” that are targeted to enable affordable personalized medicine.

Many of these developments, such as the joint research from Columbia University and University of Pennsylvania referenced above and work at Harvard University from late last year, have improved the electronics that boost the faint signal generated when DNA passes through the nanopore. Both of these research teams turned away from the more common method of slowing the DNA down as it passes through the nanopore. 

In research coming out of the University of Washington, it seems that slowing down the DNA as it passes through the nanopore has been revisited as a method for improving the signal and identifying the DNA. But in so doing, the researchers developed a unique method that combines a specially adapted, highly sensitive nanopore with a molecular motor.

"We augmented a protein nanopore we developed for this purpose with a molecular motor that moves a DNA strand through the pore a nucleotide at a time," says Jens Gundlach, a University of Washington physics professor who leads the research team, in a press release covering the research. “The motor pulls the strand through the pore at a manageable speed of tens of milliseconds per nucleotide, which is slow enough to be able to read the current signal.”

The research, which was published in the 25 March online version of Nature Biotechnology, demonstrated how an enzyme that is associated with the replication of a virus could serve as the molecular motor. While researchers at the University of California Santa Cruz had produced this molecular motor before, this time Gundlach and his colleagues attached the motor to a more sensitive kind of nanopore that could distinguish different nucleotide types.

Gundlach believes that this unique combination of molecular motor and highly sensitive nanopore could be used to identify epigenetic DNA modifications, in which DNA is modified within a specific individual.

"Epigenetic modifications are rather important for things like cancer," he said. Being able to provide DNA sequencing that can identify epigenetic changes "is one of the charms of the nanopore sequencing method."

Figure: University of Washington

A123 Systems' Nano-enbabled Battery for Electric Vehicles Runs into Manufacturing Snafu

At the time of its introduction A123 Systems's nano-enabled technology for lithium-ion batteries was heralded as a breakthrough  technology that would bring electric vehicles (EVs) one step closer to wide commercial adoption.

This rosy scenario started to reveal its thorny side when questions arose about whether Li-ion battery technology—nano-enabled or otherwise—could really meet the requirements of EV propulsion.This doubt was referred to by none other than U.S. Energy Secretary Steven Chu at the United Nations Climate Change Conference in Cancun in 2010.

With Ener1--another lithium-ion battery maker--filing for bankruptcy earlier this year, the market for nano-enabled Li-ion batteries for EVs needed some encouraging news.

Unfortunately, it did not get it this week with news that A123 will need to replace batteries used by electric sports car maker Fisker Karma among others. The recall will cost A123 Systems US $55 million.

It does not appear that there is any intrinsic problem with the batteries. Instead, one welding machine was calibrated incorrectly, resulting in a misalignment of some components in a battery cell. The problem can cause a break in the battery's electrical insulation and a potential short circuit, according to David Vieau, A123’s CEO.

While an unexpected $55-million manufacturing cost presents a problem, one can imagine that $249 million the company received from the federal government to build the plant in the first place should take some of the sting out of this unforeseen outlay. But it is probably the sagging demand for EVs that poses a far more worrisome problem for companies like A123 across the entire EV value chain.

For instance, Fisker Karma, one of the automobile manufacturers impacted by this battery manufacturing snafu, reported a net loss of $85 million this month in its fourth quarter on revenue of $40.4 million.

David Vieau may be correct in saying that problems like this manufacturing hitch are not totally unexpected in a new industry. However, this new industry may be facing a far more fundamental problem: not enough people want to buy the products they enable.

Thermoelectric Materials Turning Increasingly Towards Nanotechnology

Thermoelectric materials’ ability to generate an electrical current simply from differences in temperature has been a seductive proposition for providing sustainable energy solutions. And for good reason. If you placed a thermoelectric material next to a heat source, like a laptop battery, the electrons in the material would move to the cool side of the material thereby generating an electrical current. So, you can generate electricity just from waste heat from all sorts of machines and devices.

It’s an intriguing idea, but there are a couple of problems. The materials people have been experimenting with either possess a pretty poor thermoelectric conversion efficiency or they are prohibitively expensive for commercial uses.

With these challenges in mind, researchers are turning increasingly towards nanomaterials for solutions. Last month, I reported on Wake Forest researchers using multi-walled carbon nanotubes to fabricate a thin film that the researchers claim can convert differences in temperature into electrical energy more efficiently and more inexpensively than existing solutions.

The latest news comes from collaborative research between the California Institute of Technology, the Chinese Academy of Science's Shanghai Institute of Ceramics, Brookhaven National Laboratory and the University of Michigan. This international team has developed a liquid-like material in which selenium atoms make a crystal lattice and copper atoms flow through the crystal structure like a liquid.

"It's like a wet sponge," explains Jeff Snyder, a faculty associate in applied physics and materials science in the Division of Engineering and Applied Science at Caltech and a member of the research team. "If you have a sponge with very fine pores in it, it looks and acts like a solid. But inside, the water molecules are diffusing just as fast as they would if they were a regular liquid. That's how I imagine this material works. It has a solid framework of selenium atoms, but the copper atoms are diffusing around as fast as they would in a liquid."

The research, which was published in the journal Nature Materials, found that this unusual behavior of the copper ions around the selenium lattice resulted in very low thermal conductivity (bad at conducting heat) in what is otherwise a fairly simple semiconductor (good at conducting electricity), making it an excellent candidate as a thermoelectric material and a relatively inexpensive one.

The liquid quality of the material limits the heat-carrying vibrations so they can only travel in longitudinal waves, which results in the material being less thermally conductive than a solid material. Then in combination with the crystal structure of the selenium, which helps conduct electricity, the copper-selenium material has the thermoelectric figure of merit (thermoelectric efficiency) of 1.5 at 1000 degrees Kelvin, one of the highest values for a bulk material, according to the researchers.

Interestingly, NASA scientists had worked with a copper-selenium material 40 years ago, but because the material had this liquid-like property they found it difficult to work with. Now with this research that identifies and explains why the material has such excellent thermoelectric properties, Snyder believes that it could open up liquid-like thermoelectric materials for further research.

Custom IC Boosts Speed of Nanopore Measurements in DNA Sequencing

In the march toward inexpensive DNA sequencing, so-called “nanopore sequencing” has shown itself to be a promising technology.

However, there has been one major drawback with the nanopore solution: The weakness of the signals generated from the nanopores when the DNA passes through them. To compensate for this, researchers have mainly tried to slow the DNA as it moves through the nanopores.

Late last year, IEEE Spectrum reported on research coming from a Harvard team that was taking a different approach. Instead of trying to slow down the DNA, the team, which is part of chemistry professor Charles Lieber’s laboratory, looked at boosting the signal from the electronics.

Now researchers at Columbia, led by electrical engineering professor Ken Shepard, together with colleagues at the University of Pennsylvania, have followed in this vein by developing a custom integrated circuit using commercial semiconductor technology that should boost the signal from the nanopores and speed up the measurements. The research was described in an article on Physorg.com.

"We put a tiny amplifier chip directly into the liquid chamber next to the nanopore, and the signals are so clean that we can see single molecules passing through the pore in only one microsecond," says Jacob Rosenstein, a Ph.D. candidate in electrical engineering at Columbia and lead author of the paper. "Previously, scientists could only see molecules that stay in the pore for more than 10 microseconds."

The research team, which has published its work in the journal Nature Methods, found previous circuitry simply wasn't up to the task.

"We saw that nearly everybody else measures nanopores using classical electrophysiology amplifiers, which are mostly optimized for slower measurements," Physorg quoted Shepard as saying. "So we designed our own integrated circuit instead."

Their measurement platform involves a CMOS preamplifier with solid-state nanopores in thin silicon nitride membranes.

Shepard and his team appear confident that they can produce dramatic improvements to the technology. "With a next-generation design, we may be able to get a further 10X improvement, and measure events that last only 100 nanoseconds,” says Shepard. “Our lab is also working with other electronic single-molecule techniques based on carbon nanotube transistors, which can leverage similar electronic circuits. This is an exciting time!"

Graphene-Silicon Anodes for Li-ion Batteries Go Commercial

 

Recently researchers at the U.S. Department of Energy's Pacific Northwest National Laboratory have been examining the problem of limited charge-discharge cycles in the lives of nanostructured silicon anodes on lithium-ion batteries.

While nanostructured silicon anodes have a longer life than the pure silicon variety, they are still not up to the standards set by lowly old graphite in this respect. But it appears that one company is undeterred by this drawback.

California Lithium Battery Inc. (CalBattery) announced last week that it has entered into a Work for Others (WFO) agreement with Argonne National Laboratory (ANL) to commercialize what is being dubbed the “GEN3” lithium-ion battery. The GEN3 battery is largely based on Argonne’s provisionally patented silicon-graphene battery anode process

(On a bit of a side note, the researchers who were named in the anode patent are all part of the Hersam Research Group at Northwestern University, which seems to be growing into a leader in the development of graphene-based silicon anodes.)

In the press release and the video below, CalBattery says that it can produce the GEN3 battery in the United States at a cost reduction of 70 percent. I’m not sure what they're comparing it to—nor if that means they are reducing the production costs by 70 percent or the actual purchase price of the Li-ion battery by that amount. But in any case, it seems they believe that this cost reduction will be a “huge breakthrough.”

 

 

According to Phil Roberts, CEO of CalBattery, the plan is to use a Very Large Format (VLF) battery and apply the new graphene-enabled silicon anodes to them.

“Incredibly, some energy storage systems providers and independent power producers today are using hundreds of thousands, if not millions, of small cylindrical cell batteries in massive utility-scale storage systems. This approach is simply too costly and not viable. Large storage must be built from large batteries, not small batteries originally designed for powered hand tools. Our VLF battery has a clear performance and cost advantage in providing the massive currents needed with the minimum materials and battery management components, resulting in a more affordable lithium-ion battery for wide-scale use.”

It is encouraging news that some commercial interests are looking to bring a recently developed nanotechnology-enabled solution for improving Li-ion batteries to market . However, my enthusiasm is somewhat tempered by the emphasis that is being placed on refining the battery for electric vehicle (EV) applications. 

I suppose this interest in the EV market is why they decided to apply the graphene-silicon anodes to the VLF batteries. Maybe that can make the difference in an arena where so many companies are struggling or have failed outright.

 

Engineering of Graphene Gives it Piezoelectric Properties

Researchers at Stanford University are extending the capabilities of graphene by engineering piezoelectric capabilities into the material.

"The physical deformations we can create are directly proportional to the electrical field applied and this represents a fundamentally new way to control electronics at the nanoscale," says Evan Reed, head of the Materials Computation and Theory Group at Stanford and senior author of the study. "This phenomenon brings new dimension to the concept of 'straintronics' for the way the electrical field strains—or deforms—the lattice of carbon, causing it to change shape in predictable ways."

The concept of ‘straintronics’ in Graphene was demonstrated at least as far back as 2010 when Lawrence Berkeley National Laboratory research, led by Michael Crommie, professor of physics at UC Berkeley and a faculty researcher at LBNL, serendipitously discovered that when graphene was grown on platinum a strain pattern was created.

It should be noted that the Stanford research, which was published in the journal ACS Nano,  was conducted within modeling and simulation software. Nonetheless the researchers achieved their piezoelectric effect quite deliberately in the models by depositing lithium, hydrogen, potassium and fluorine atoms on one side of the graphene lattice. They expected this to generate a piezoelectric effect, but not on the scale they witnessed in the models.

“We thought the piezoelectric effect would be present, but relatively small. Yet, we were able to achieve piezoelectric levels comparable to traditional three-dimensional materials," said Reed. "It was pretty significant."

While the level of the piezoelectric effect was unexpected, the real breakthrough here may be that they were able to control the effect by depositing the atoms in specific locations within the graphene.

"We were further able to fine tune the effect by pattern doping the graphene—selectively placing atoms in specific sections and not others," said Mitchell Ong, a post-doctoral scholar in Reed's lab and first author of the paper. "We call it designer piezoelectricity because it allows us to strategically control where, when and how much the graphene is deformed by an applied electrical field with promising implications for engineering."

It should be interesting to see if anyone takes on these simulations and starts running physical experiments. If it can be duplicated in physical experiments, it could open the possibility for this kind of doping to be used on other nanomaterials that could open their use in a number of application areas, ranging from energy harvesting to chemical sensing and high-frequency acoustics.

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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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