Nanoclast

Graphene is certainly the “wonder material” of the moment, surpassing the former bearer of that title—carbon nanotubes. To support this research, funding mechanisms around the world are cranking up to full throttle. Some large investments in the UK to secure its position as a “graphene hub” and the €1 billion the EU has poured into graphene research are just the most recent examples of this.

Presumably all this research and all this funding is intended—eventually—to lead to some commercial applications. Things appear to be moving in the right direction with some significant advances in the mass production of graphene (liquid phase, thermal exfoliation, and chemical vapor deposition, to name a few).

Then again, you can mass-produce sealing wax but there’s not a whole lot of demand for the material anymore. To see what cheap production of a nanomaterial gets you, just take a look at the huge capacity glut for multi-walled carbon nanotubes that have left producers begging for applications.

Even the so-called “patent surge” in graphene doesn’t promise much more than the old “patented nanomaterial and a prayer” sensibility that governed investment in the early 2000s. 

There remains a very real possibility at this stage that graphene funding will not produce new economic development for some regions any more than investments in carbon nanotubes did.

Nonetheless there are real applications for which graphene could be used today. Those applications may not be—at least immediately—in the electronics industry, desperate though it is to keep Moore’s Law alive for another generation, but in more mundane areas such as for membranes for natural gas processing or water purification.

With this landscape as the backdrop, the National Science Foundation (NSF) wanted to highlight Jessup, Md.-based Vorbeck Materials, which just received a grant from the NSF to bring its graphene-based technology to market.

According to the NSF press release, the company claims to be “one of the first (if not the first) graphene products to go to market.” In 2009, Vorbeck introduced its Vor-ink graphene-based conductive ink for electronics at the Printed Electronics Europe 2009 tradeshow.

Quantum dots have attracted a lot of interest for researchers in photovoltaics because of their claimed ability to achieve extraordinary conversion efficiencies.

Last year researchers at the University of Buffalo said they could reach 45-percent conversion efficiency with solar cells enabled by quantum dots. And for nearly a decade now quantum dots have even been proposed as a way to achieve electron multiplication or to create so-called “hot carrier” cells for reaching higher conversion rates. However, this line of research has earned some skeptics of late who dismiss the possibility that more than one electron-hole pair can be generated from one photon.

Now researchers at the National Renewable Energy Laboratory (NREL) in conjunction with an international team have demonstrated that quantum dots can self assemble onto nanowires in a way that once again promises improved conversion efficiencies for photovoltaics.

Among their key discoveries, which were published in the journal Nature Materials “Self-assembled Quantum Dots in a Nanowire System for Quantum Photonics,” was that the quantum dots self assemble at the apex of the gallium arsenide/aluminum gallium arsenide core/shell nanowire interface. Further the quantum dots can be positioned precisely relative to the center of the nanowire. When this precise positioning is combined with quantum dots’ ability to confine both the electrons and the holes, the possibilities for this approach look encouraging.

In high-energy materials, the electrons and holes would typically locate themselves at the lowest energy position. But because the quantum dots can create this quantum confinement the electrons and holes overlap so that they are confined within the quantum dot, which stays located at the high-energy position. The high-energy position for this material is the gallium-arsenide core. This location results in the quantum dots being extraordinarily bright while maintaining a narrow spectral range.

While Swiss scientists had proposed this quantum confinement previously, no one quite believed them, according to Jun-Wei Luo, one of the co-authors of the study. This disbelief set Luo onto developing the quantum-dot-in-nanowire system that validated the previous research. While using NREL’s supercomputer he determined that despite the fact that the band edges were formed by the gallium Arsenide core, the aluminum-rich edges provided the quantum confinement that is observed.

In addition to applications in photovoltaics, this development should impact any area in which the detection of electric and magnetic fields are involved.

Images: NREL

In emerging technologies—of which, nanotechnology is a leading example—it's important to recognize and encourage innovation wherever it exists, because the ecosystem in which it flourishes is so delicate. There is the so-called funding—or innovation—gap that the President’s Council on Science and Technology (PCAST) tried to tackle a couple of years back. But even if an emerging technology does get the funding to go commercial, it seems the chances of its success are so remote that it’s amazing that any new technologies come to market at all. One need only look at the examples of A123 Systems or the UK-based Oxonica to see how large amounts of funding are no guarantee that an emerging technology—and a nanotechnology in these cases—will result in a successful business.

And so, following up a suggestion from a reader that I cover the personalities within the field of nanotechnology, we're starting a Q&A series with researchers and other leaders, beginning with Eric Mayes, currently the CEO of UK-based Endomagnetics Ltd., which is “addressing cancer staging and healthcare challenges through the application of advanced magnetic sensing technology and nanotechnology.” In addition, Eric is a true pioneer in the commercialization of a nanotechnology product. He was the founder of Nanomagnetics and served first as its CTO between 1997 and 2002 and then as the company’s CEO from 2003 to 2006.

Nanomagnetics’ primary application focus was in the data storage market. But I came to know Eric by inviting him to speak at a conference on how Nanomagnetics’ use of an iron-storage protein ferritin to make nanoscale magnetic particles could be exploited to enable forward osmosis for water purification. It was really an elegant approach and captured my interest as it did the audience of the conference.

Like other small companies that have dared to challenge the big data storage behemoths it was a rocky nearly-decade-long road for Nanomagentics that ended when the company finally closed its doors in 2006.

Last year I saw that Eric was leading a new company—Endomagnetics. It has a novel medical diagnostic tool for detecting the likely sites for cancer-infected lymph nodes to help provide early diagnosis for breast cancer. He and his new company were highlighted in a BBC News Horizon feature on nanotechnology. A video of the interview can be found here.

So, I decided to catch up with Eric and ask him about his new venture and for him to discuss the innovation landscape for nanotechnology and how it has evolved over the last 15 years.

With each passing day we are becoming more intertwined into the Internet of Things, where each and every object in the world—your clothes closet and every article of clothing in it, your dishwasher and every dish in it, and so on—has its own IP address. Obviously, they will communicate wirelessly. That takes power and, in many cases, frequent battery changes.

Now Peter Kinget, a professor or electrical engineering at Columbia University, and his colleagues have developed a nanoscale chip that requires so little energy in transmitting wireless signals that the batteries may never need to be replaced.

The chip will be presented at the at the IEEE International Solid-State Circuits Conference (ISSCC) meeting  in two weeks by Kinget's Ph.D. student Baradwaj Vigraham under the user-friendly title "A Self-Duty-Cycled and Synchronized UWB Receiver SoC Consuming 375pJ/bit for -76.5dBm Sensitivity at 2Mbps."

The research is part of a larger, award-winning research program called EnHANTs. “The goal of Enhants is to make thin, flexible, energy self-reliant tags that can be attached to common objects (clothes, furniture, toys, books, walls, windows, shelves, etc.) in our environment for applications such as the Internet of Things, logistics, tracking and search, or disaster recovery,” explains Kinget.

To this end the credit-card-size tags Kinget and his collaborators (Gil Zussman and John Kymissis) have developed will collect energy with photovoltaic cells. The photovoltaics will draw energy from artificial light in addition to sunlight since indoor applications are of key interest.

Technological development is all about finding engineering solutions to scientific theories, and this is especially true in the field of nanotechnology. The work of Gerd Binnig and Heinrich Rohrer in inventing the Scanning Tunneling Microscope comes to mind as an example of trying to engineer something of substance out of little more than an idea based on some sound physics.

Now Brian Willis, associate professor of chemical, materials, and biomolecular engineering at the University of Connecticut, is applying his atomic layer deposition (ALD) fabrication process, which he developed in 2011 while at the University of Delaware, to create nano-antenna arrays for highly efficient solar power devices.

The theory is straightforward: If you could build nano-antenna arrays so that the core electrodes were no more than 1 or 2 nanometers apart, they would serve to both absorb and rectify solar energy—thus the name “rectennas.” These rectennas should be able to collect as much as 70 percent of the sun’s electromagnetic radiation and simultaneously convert that light into direct current electrical power.

With those kinds of potential yields (no pun intended), research into nano-antenna arrays has been growing of late, with some of the more recent research out of MIT looking at ways of using them for holographic TVs. However, for the specific use in photovoltaics the problem has been getting the core electrodes close enough. The best that could be previously achieved, using electron guns, was somewhere in the neighborhood of a 10 to 20 nanometers gap between the core electrodes.

This is where Willis comes in. After the core electrodes have been cut with an electron gun so that one of the pair of electrodes has been shaped into a sharp tip, Willis is able to coat the surfaces of both electrodes with copper atoms using his ALD process, reducing the gap to 1.5 nanometers.

The history of nanotechnology-based solutions for making fuel cells less expensive or more efficient has not really been what you would call a huge success. But a decade ago it seemed the focus on applying nanomaterials to areas such as improved catalysts for fuel cells was driven more by exploiting what the nanomaterials were good at rather than by what fuel cells needed to be more commercially viable.

Lately that dynamic has changed and nanotechnology has been finding itself more useful when it comes to cheap ways to isolate hydrogen—the high cost of which has been a key obstacle in reaching the so-called “hydrogen economy” where we can drive around in hydrogen-powered automobiles and power our mobile devices with fuel cells.

Three years ago, Angela Belcher at MIT mimicked the process of photosynthesis by developing a man-made virus that could effectively split water molecules into hydrogen and oxygen. Another team, at the University of California, also duplicated photosynthesis, but instead of exotic man-made viruses used a simpler nanowire-based material to cut the water molecules into its constituent parts.

The current state of the art for the artificial photosynthesis approach to isolating hydrogen may have been marked by HyperSolar Inc.’s announcement last year to commercialize a zero-carbon process for hydrogen gas production.

But now researchers at the University of Buffalo—in research published in the journal Nano Letters—have developed a new nanomaterial-based method for producing hydrogen that doesn’t require any light to activate the process. They have reduced silicon down to 10-nanometer particles so that when water is added the reaction produces hydrogen gas quickly and abundantly.

The struggle for which material will be the de facto choice for two-dimensional (2-D) devices in future electronics has been ratcheting up over the last couple of years. In July of last year, IEEE Spectrum covered the development of the long-predicted single-layer thick structure of silicon, known as silicene.  2-D silicon is expected to have some of the same remarkable characteristics as graphene, but deliver them in a material that the semiconductor industry has been working with for decades.

Another material that has been pushing graphene for the throne of the 2-D material of the future has been molybdenum disulfide (MoS2).  Two years ago it seemed that at best MoS2 could achieve would to be simply a complimentary material to graphene in applications that required transparent semiconductors.  Over the last six months, it’s no longer clear that MoS2 shouldn't have it's own starring role.  

So it would seem that graphene needs to step up its game if it’s to stake its claim to the 2-D material of the future for electronics applications. Researchers at Rice University have taken up the challenge and developed a process that can be duplicated with lithography techniques to weave graphene (the conductor) with hexagonal boron nitride (h-BN) (the insulator) to create patterns at nanoscale dimensions.

The research, which was published in the journal Nature Nanotechnology (“In-plane heterostructures of graphene and hexagonal boron nitride with controlled domain sizes”), is the latest evolution of a technique that was developed at Rice nearly three years ago. What distinguishes this new version is that the researchers were able to shrink the 2-D devices to even smaller dimensions.

Those associated with the UK government’s nanotechnology efforts have often pointed out that the country's first national nanotechnology initiative the UK Department of Trade and Industry’s National Initiative on Nanotechnology (NION) came into existence in 1986—a decade and a half before the United States formed its own National Nanotechnology Initiative in 2001. This historical reminder is seldom told as a matter of pride, but as a cautionary tale. After starting off as a world leader in the field, the UK has fallen farther behind the U.S., Germany, and Japan with each passing year.

Because of this belief that it let a treasure escape out of the front door, the UK government has been determined to not let history repeat itself with its handling of graphene research and commercialization. The British feel a kind of ownership of graphene ever since two Russian émigrés, Andre Geim and Konstantin Novoselov, created single-atom-thick sheets of carbon back in 2004 while at the University of Manchester. The UK government is determined to stake its claim in nanotechnology, with graphene as its quarry. To ensure that it gets the most commercialization bang for its development buck, the government began revealing plans last year aimed at making the UK a “graphene hub." And this time they were going to put their money where their mouth was, investing around US $71 million in a single research facility at the University of Manchester. In the past, the UK has been reluctant to invest in nanotechnology even if it meant some of their homegrown companies would move abroad.

Despite bold plans and investments, it was reported earlier this month that the UK had already fallen dramatically behind in graphene-related patents.

The Boeing Dreamliner's problematic choice of a lithium-ion (Li-ion) battery designed around a cobalt oxide (CoO2) chemistry is making everyone a little nervous about Li-ion batteries in general. It harkens back to the mid-2000s when electronics giants apologetically had to recall the Li-ion batteries used in their laptop computers.

The CoO2 chemistry used in Li-Co-O2 batteries offers more power for its weight than the Li-Ti-O variety, but is less stable. However, if a better electrolyte solvent could be developed, much of that instability could be mitigated. (A commenter astutely discussed this topic in a response to a recent blog post.)

Along these lines, researchers at Oak Ridge National Laboratory (ORNL) have developed a nanostructured solid electrolyte for more energy-dense Li-ion batteries. They expect that replacing liquid electrolytes in Li-ion batteries with solid ones should lead to safer batteries.

"To make a safer, lightweight battery, we need the design at the beginning to have safety in mind," said ORNL's leader researcher, Chengdu Liang, in a press release. "We started with a conventional material that is highly stable in a battery system—in particular one that is compatible with a lithium metal anode."

Gold in nanoparticle form is perhaps more precious than the macroscale variety when it comes to treating diseases. While the usual application areas for nanotechnology, such as electronics, are finding uses for gold nanoparticles, it is perhaps in the area of drug delivery and the detection and treatments of diseases such as cancer where they are destined to have their biggest impact.

Along these lines, researchers at Northwestern University have used gold nanoparticles to treat a common form of cancer, known as B-cell lymphoma—the most common type of non-Hodgkin lymphoma.

In research to be published in the journal Proceedings of the National Academy of Sciences, C. Shad Thaxton, M.D., and Leo I. Gordon, M.D. showed that they could trick B-cell lymphoma, which prefers to eat HDL (high-density lipoprotein) cholesterol—otherwise known as the “good cholesterol”—into eating gold nanoparticles instead of the HDL. Once the B-cell lymphoma cells start eating the gold nanoparticles (or artificial HDL particles), they get plugged up and can no longer feed on any more cholesterol. Deprived of their favorite food, the lymphoma cells essentially starve to death.