Tag Archives: carbon nanotubes

Boron nitride-graphene hybrid nanostructures could lead to next generation ‘green’ cars

An Oct. 24, 2016 phys.org news item describes research which may lead to improved fuel storage in ‘green’ cars,

Layers of graphene separated by nanotube pillars of boron nitride may be a suitable material to store hydrogen fuel in cars, according to Rice University scientists.

The Department of Energy has set benchmarks for storage materials that would make hydrogen a practical fuel for light-duty vehicles. The Rice lab of materials scientist Rouzbeh Shahsavari determined in a new computational study that pillared boron nitride and graphene could be a candidate.

An Oct. 24, 2016 Rice University news release (also on EurekAlert), which originated the news item, provides more detail (Note: Links have been removed),

Shahsavari’s lab had already determined through computer models how tough and resilient pillared graphene structures would be, and later worked boron nitride nanotubes into the mix to model a unique three-dimensional architecture. (Samples of boron nitride nanotubes seamlessly bonded to graphene have been made.)

Just as pillars in a building make space between floors for people, pillars in boron nitride graphene make space for hydrogen atoms. The challenge is to make them enter and stay in sufficient numbers and exit upon demand.

In their latest molecular dynamics simulations, the researchers found that either pillared graphene or pillared boron nitride graphene would offer abundant surface area (about 2,547 square meters per gram) with good recyclable properties under ambient conditions. Their models showed adding oxygen or lithium to the materials would make them even better at binding hydrogen.

They focused the simulations on four variants: pillared structures of boron nitride or pillared boron nitride graphene doped with either oxygen or lithium. At room temperature and in ambient pressure, oxygen-doped boron nitride graphene proved the best, holding 11.6 percent of its weight in hydrogen (its gravimetric capacity) and about 60 grams per liter (its volumetric capacity); it easily beat competing technologies like porous boron nitride, metal oxide frameworks and carbon nanotubes.

At a chilly -321 degrees Fahrenheit, the material held 14.77 percent of its weight in hydrogen.

The Department of Energy’s current target for economic storage media is the ability to store more than 5.5 percent of its weight and 40 grams per liter in hydrogen under moderate conditions. The ultimate targets are 7.5 weight percent and 70 grams per liter.

Shahsavari said hydrogen atoms adsorbed to the undoped pillared boron nitride graphene, thanks to  weak van der Waals forces. When the material was doped with oxygen, the atoms bonded strongly with the hybrid and created a better surface for incoming hydrogen, which Shahsavari said would likely be delivered under pressure and would exit when pressure is released.

“Adding oxygen to the substrate gives us good bonding because of the nature of the charges and their interactions,” he said. “Oxygen and hydrogen are known to have good chemical affinity.”

He said the polarized nature of the boron nitride where it bonds with the graphene and the electron mobility of the graphene itself make the material highly tunable for applications.

“What we’re looking for is the sweet spot,” Shahsavari said, describing the ideal conditions as a balance between the material’s surface area and weight, as well as the operating temperatures and pressures. “This is only practical through computational modeling, because we can test a lot of variations very quickly. It would take experimentalists months to do what takes us only days.”

He said the structures should be robust enough to easily surpass the Department of Energy requirement that a hydrogen fuel tank be able to withstand 1,500 charge-discharge cycles.

Shayeganfar [Farzaneh Shayeganfar], a former visiting scholar at Rice, is an instructor at Shahid Rajaee Teacher Training University in Tehran, Iran.

 

Caption: Simulations by Rice University scientists show that pillared graphene boron nitride may be a suitable storage medium for hydrogen-powered vehicles. Above, the pink (boron) and blue (nitrogen) pillars serve as spacers for carbon graphene sheets (gray). The researchers showed the material worked best when doped with oxygen atoms (red), which enhanced its ability to adsorb and desorb hydrogen (white). Credit: Lei Tao/Rice University

Caption: Simulations by Rice University scientists show that pillared graphene boron nitride may be a suitable storage medium for hydrogen-powered vehicles. Above, the pink (boron) and blue (nitrogen) pillars serve as spacers for carbon graphene sheets (gray). The researchers showed the material worked best when doped with oxygen atoms (red), which enhanced its ability to adsorb and desorb hydrogen (white). Credit: Lei Tao/Rice University

Here’s a link to and a citation for the paper,

Oxygen and Lithium Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage by Farzaneh Shayeganfar and Rouzbeh Shahsavari. Langmuir,  DOI: 10.1021/acs.langmuir.6b02997 Publication Date (Web): October 23, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

I last featured research by Shayeganfar and  Shahsavari on graphene and boron nitride in a Jan. 14, 2016 posting.

Self-healing lithium-ion batteries for textiles

It’s easy to forget how hard we are on our textiles. We rip them, step on them, agitate them in water, splatter them with mud, and more. So, what happens when we integrate batteries and electronics into them? An Oct. 20, 2016 news item on phys.org describes one of the latest ‘textile batter technologies’,

Electronics that can be embedded in clothing are a growing trend. However, power sources remain a problem. In the journal Angewandte Chemie, scientists have now introduced thin, flexible, lithium ion batteries with self-healing properties that can be safely worn on the body. Even after completely breaking apart, the battery can grow back together without significant impact on its electrochemical properties.

wiley_selfhealinglithiumionbattery

© Wiley-VCH

An Oct. 20, 2016 Wiley Angewandte Chemie International Edition press release (also on EurekAlert), which originated the news item, describes some of the problems associated with lithium-ion batteries and this new technology designed to address them,

Existing lithium ion batteries for wearable electronics can be bent and rolled up without any problems, but can break when they are twisted too far or accidentally stepped on—which can happen often when being worn. This damage not only causes the battery to fail, it can also cause a safety problem: Flammable, toxic, or corrosive gases or liquids may leak out.

A team led by Yonggang Wang and Huisheng Peng has now developed a new family of lithium ion batteries that can overcome such accidents thanks to their amazing self-healing powers. In order for a complicated object like a battery to be made self-healing, all of its individual components must also be self-healing. The scientists from Fudan University (Shanghai, China), the Samsung Advanced Institute of Technology (South Korea), and the Samsung R&D Institute China, have now been able to accomplish this.

The electrodes in these batteries consist of layers of parallel carbon nanotubes. Between the layers, the scientists embedded the necessary lithium compounds in nanoparticle form (LiMn2O4 for one electrode, LiTi2(PO4)3 for the other). In contrast to conventional lithium ion batteries, the lithium compounds cannot leak out of the electrodes, either while in use or after a break. The thin layer electrodes are each fixed on a substrate of self-healing polymer. Between the electrodes is a novel, solvent-free electrolyte made from a cellulose-based gel with an aqueous lithium sulfate solution embedded in it. This gel electrolyte also serves as a separation layer between the electrodes.

After a break, it is only necessary to press the broken ends together for a few seconds for them to grow back together. Both the self-healing polymer and the carbon nanotubes “stick” back together perfectly. The parallel arrangement of the nanotubes allows them to come together much better than layers of disordered carbon nanotubes. The electrolyte also poses no problems. Whereas conventional electrolytes decompose immediately upon exposure to air, the new gel is stable. Free of organic solvents, it is neither flammable nor toxic, making it safe for this application.

The capacity and charging/discharging properties of a battery “armband” placed around a doll’s elbow were maintained, even after repeated break/self-healing cycles.

Here’s a link to and a citation for the paper,

A Self-Healing Aqueous Lithium-Ion Battery by Yang Zhao, Ye Zhang, Hao Sun, Xiaoli Dong, Jingyu Cao, Lie Wang, Yifan Xu, Jing Ren, Yunil Hwang, Dr. In Hyuk Son, Dr. Xianliang Huang, Prof. Yonggang Wang, and Prof. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201607951 Version of Record online: 12 OCT 2016

© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Brain and machine as one (machine/flesh)

The essay on brains and machines becoming intertwined is making the rounds. First stop on my tour was its Oct. 4, 2016 appearance on the Mail & Guardian, then there was its Oct. 3, 2016 appearance on The Conversation, and finally (moving forward in time) there was its Oct. 4, 2016 appearance on the World Economic Forum website as part of their Final Frontier series.

The essay was written by Richard Jones of Sheffield University (mentioned here many times before but most recently in a Sept. 4, 2014 posting). His book ‘Soft Machines’ provided me with an important and eminently readable introduction to nanotechnology. He is a professor of physics at the University of Sheffield and here’s more from his essay (Oct. 3, 2016 on The Conversation) about brains and machines (Note: Links have been removed),

Imagine a condition that leaves you fully conscious, but unable to move or communicate, as some victims of severe strokes or other neurological damage experience. This is locked-in syndrome, when the outward connections from the brain to the rest of the world are severed. Technology is beginning to promise ways of remaking these connections, but is it our ingenuity or the brain’s that is making it happen?

Ever since an 18th-century biologist called Luigi Galvani made a dead frog twitch we have known that there is a connection between electricity and the operation of the nervous system. We now know that the signals in neurons in the brain are propagated as pulses of electrical potential, whose effects can be detected by electrodes in close proximity. So in principle, we should be able to build an outward neural interface system – that is to say, a device that turns thought into action.

In fact, we already have the first outward neural interface system to be tested in humans. It is called BrainGate and consists of an array of micro-electrodes, implanted into the part of the brain concerned with controlling arm movements. Signals from the micro-electrodes are decoded and used to control the movement of a cursor on a screen, or the motion of a robotic arm.

A crucial feature of these systems is the need for some kind of feedback. A patient must be able to see the effect of their willed patterns of thought on the movement of the cursor. What’s remarkable is the ability of the brain to adapt to these artificial systems, learning to control them better.

You can find out more about BrainGate in my May 17, 2012 posting which also features a video of a woman controlling a mechanical arm so she can drink from a cup coffee by herself for the first time in 15 years.

Jones goes on to describe the cochlear implants (although there’s no mention of the controversy; not everyone believes they’re a good idea) and retinal implants that are currently available. Jones notes this (Note Links have been removed),

The key message of all this is that brain interfaces now are a reality and that the current versions will undoubtedly be improved. In the near future, for many deaf and blind people, for people with severe disabilities – including, perhaps, locked-in syndrome – there are very real prospects that some of their lost capabilities might be at least partially restored.

Until then, our current neural interface systems are very crude. One problem is size; the micro-electrodes in use now, with diameters of tens of microns, may seem tiny, but they are still coarse compared to the sub-micron dimensions of individual nerve fibres. And there is a problem of scale. The BrainGate system, for example, consists of 100 micro-electrodes in a square array; compare that to the many tens of billions of neurons in the brain. The fact these devices work at all is perhaps more a testament to the adaptability of the human brain than to our technological prowess.

Scale models

So the challenge is to build neural interfaces on scales that better match the structures of biology. Here, we move into the world of nanotechnology. There has been much work in the laboratory to make nano-electronic structures small enough to read out the activity of a single neuron. In the 1990s, Peter Fromherz, at the Max Planck Institute for Biochemistry, was a pioneer of using silicon field effect transistors, similar to those used in commercial microprocessors, to interact with cultured neurons. In 2006, Charles Lieber’s group at Harvard succeeded in using transistors made from single carbon nanotubes – whiskers of carbon just one nanometer in diameter – to measure the propagation of single nerve pulses along the nerve fibres.

But these successes have been achieved, not in whole organisms, but in cultured nerve cells which are typically on something like the surface of a silicon wafer. It’s going to be a challenge to extend these methods into three dimensions, to interface with a living brain. Perhaps the most promising direction will be to create a 3D “scaffold” incorporating nano-electronics, and then to persuade growing nerve cells to infiltrate it to create what would in effect be cyborg tissue – living cells and inorganic electronics intimately mixed.

I have featured Charles Lieber and his work here in two recent posts: ‘Bionic’ cardiac patch with nanoelectric scaffolds and living cells on July 11, 2016 and Long-term brain mapping with injectable electronics on Sept. 22, 2016.

For anyone interested in more about the controversy regarding cochlear implants, there’s this page on the Brown University (US) website. You might also want to check out Gregor Wolbring (professor at the University of Calgary) who has written extensively on the concept of ableism (links to his work can be found at the end of this post). I have excerpted from an Aug. 30, 2011 post the portion where Gregor defines ‘ableism’,

From Gregor’s June 17, 2011 posting on the FedCan blog,

The term ableism evolved from the disabled people rights movements in the United States and Britain during the 1960s and 1970s.  It questions and highlights the prejudice and discrimination experienced by persons whose body structure and ability functioning were labelled as ‘impaired’ as sub species-typical. Ableism of this flavor is a set of beliefs, processes and practices, which favors species-typical normative body structure based abilities. It labels ‘sub-normative’ species-typical biological structures as ‘deficient’, as not able to perform as expected.

The disabled people rights discourse and disability studies scholars question the assumption of deficiency intrinsic to ‘below the norm’ labeled body abilities and the favoritism for normative species-typical body abilities. The discourse around deafness and Deaf Culture would be one example where many hearing people expect the ability to hear. This expectation leads them to see deafness as a deficiency to be treated through medical means. In contrast, many Deaf people see hearing as an irrelevant ability and do not perceive themselves as ill and in need of gaining the ability to hear. Within the disabled people rights framework ableism was set up as a term to be used like sexism and racism to highlight unjust and inequitable treatment.

Ableism is, however, much more pervasive.

You can find out more about Gregor and his work here: http://www.crds.org/research/faculty/Gregor_Wolbring2.shtml or here:
https://www.facebook.com/GregorWolbring.

A better buckypaper

‘Buckyballs’ is a slang term for buckminster fullerenes, spheres made up of a carbon atoms arranged in hexagons. It’s a tribute of sorts to Buckminster Fuller, an architect, designer, systems theorist and more, who developed a structure known as a geodesic dome which bears a remarkable resemblance to the carbon atom spheres known as buckyballs or buckminster fullerenes or fullerenes or C60 (for a carbon-based fullerene) for short. Carbon nanotubes are sometimes called buckytubes and there is a material known as buckypaper. A Sept. 20, 2016 news item on Nanowerk describes the latest work on buckypaper,

Researchers at the Masdar Institute of Science and Technology have developed a novel type of “buckypaper” – a thin film composed of carbon nanotubes – that has better thermal and electrical properties than most types of buckypaper previously developed. Researchers believe the innovative buckypaper could be used to create ultra-lightweight composite materials for numerous aerospace and energy applications, including advanced lightning strike protection on airplanes and more powerful lithium-ion batteries.

Masdar Institute’s Associate Professors of Mechanical and Materials Engineering Dr. Rashid Abu Al-Rub and Dr. Amal Al Ghaferi, along with Post-Doctoral Researcher Dr. Hammad Younes, developed the buckypaper with carbon nanostructures provided by global security, aerospace, and information technology company Lockheed Martin.

A Sept. 20, 2016 Masdar Institute (United Arab Emirates) press release, which originated the news item, describes the research in more detail,

The black, powdery flakes provided by Lockheed Martin’s Applied NanoStructured Solutions (ANS) contain hundreds of carbon nanotubes, which are one-atom thick sheets of graphene rolled into a tube that have extraordinary mechanical, electrical and thermal properties. Lockheed Martin’s carbon nanostructures are unique because the carbon nanotubes within each flake are all properly aligned, making them good conductors of heat and electricity.

“Lockheed Martin’s carbon nanostructures have many potential applications, but in its powdery form, it cannot be used. It has to be fabricated in a way that keeps the unique properties of the carbon nanotube,” explained Dr. Al Ghaferi. “The challenge we faced was to create something useful with the carbon nanotubes without losing any of their unique properties or disturbing the alignment.”

Dr. Younes said: “Each flake is a carbon nanostructure containing many aligned carbon nanotubes. The alignment of the tubes creates a path for conductivity, much like a wire, making the nanostructure an exceptionally good conductor of electricity.”

The Masdar Institute team mixed the carbon nanotubes with a polymer and their resulting buckypaper, which successfully maintained the alignment of the carbon nanotubes, demonstrated high thermal-electrical conductivity and superior mechanical properties.

“We have a secret recipe for self-aligning the carbon nanotubes within the buckypaper. This self-aligning is key in significantly enhancing the electrical, thermal and mechanical properties of our fabricated buckypapers,” explained Dr. Abu Al-Rub.

Despite their microscopic size – a carbon nanotube’s diameter is about 10,000 times smaller than a human hair – carbon nanotubes’ impact on technology has been huge. At the individual tube level, carbon nanotubes are 200 times stronger, five times more elastic, and five times more electrically conductive than steel.

Because of their extraordinary strength, thermal and electrical properties, and miniscule size, carbon nanotubes can be used in a number of applications, including ultra-thin energy storage devices, smaller and more efficient computer chips, photovoltaic solar cells, flexible electronics, cancer detection, and lightning-resistant coatings on airplanes.

According to a report by Global Industry Analysts Inc., the current global market for nanotubes is pegged at roughly US$5 billion and its market share is growing sharply, reflecting the rising sentiment worldwide in carbon nanotubes’ potential as a wonder technology.

Masdar Institute’s efforts to capitalize on this emerging technology have resulted in several cutting-edge carbon nanotube research projects, including an attempt to create carbon nanotube-strengthened concrete, super capacitors that can hold 50 times more charge, and a membrane that can bind organic micro-pollutants.

As the UAE moves towards a clean energy future, innovations in renewable energy storage systems and other sustainable technologies are crucial for the country’s successful transition, and researchers at Masdar Institute believe that carbon nanotubes will play a huge role in achieving energy sustainability.

Here’s a link to and a citation for the paper,

Processing and property investigation of high-density carbon nanostructured papers with superior conductive and mechanical properties by Hammad Younesa, Rashid Abu Al-Ruba, Md. Mahfuzur Rahmana, Ahmed Dalaqa, Amal Al Ghaferia, Tushar Shahb. Diamond and Related Materials Volume 68, September 2016, Pages 109–117  DOI: http://dx.doi.org/10.1016/j.diamond.2016.06.016

This paper is behind a paywall.

The nanotube of a thousand faces (similar nanomaterials behaving differently)

Kudos to any one who recognizes the reference to the ‘man of a thousand faces’, Lon Chaney, a silent film horror star. As for the nanotubes, there’s this Sept. 14, 2016 news item on ScienceDaily,

Nanotubes can be used for many things: electrical circuits, batteries, innovative fabrics and more. Scientists have noted, however, that nanotubes, whose structures appear similar, can actually exhibit different properties, with important consequences in their applications. Carbon nanotubes and boron nitride nanotubes, for example, while nearly indistinguishable in their structure, can be different when it comes to friction. A study conducted by SISSA/CNR-IOM and Tel Aviv University created computer models of these crystals and studied their characteristics in detail and observed differences related to the material’s chirality. …

A Sept. 14, 2016 Scuola Internazionale Superiore di Studi Avanzati (SISSA) press release (PDF), which originated the news item, describes the research in more detail,

“We began with a series of experimental observations which showed that very similar nanotubes exhibit different frictional properties, with intensities ranging up to two orders of magnitude,” says Roberto Guerra, a researcher at CNR-IOM and the International School for Advanced Studies (SISSA) in Trieste, first author of the study. “This led us to hypothesize that the chirality of the materials may play a role in this phenomenon.” The study involving also Andrea Vanossi (CNR-IOM) and Erio Tosatti (SISSA), was conducted in collaboration with the University of Tel Aviv.

For materials, such as those used in the study, chirality is linked to the three-dimensional arrangement of the weft that form the nanotube. “If we wrap a sheet of lined paper around itself to form a tube, the angle that the lines form with the axis of the tube determines its chirality,” says Guerra. “In our work we reconstructed the behavior of double-walled nanototubes, which can be imagined as two tubes of slightly different diameters, one inside the other. We observed that the difference in chirality between the inner tube and the outer tube has a remarkable effect on the three-dimensional shape of the nanotubes.”

A polygonal tube

“If we continue with the paper metaphor, the difference in orientation between the lattice on the inner tube and the outer tube determine to what extent, and, in what way, planar regions (faces) along the tube will form,” says Guerra. To better understand what is meant by “faces,” imagine a cross section of the tube, which is polygonal rather than perfectly circular. “The smaller the difference in chirality, the clearer and more obvious the faces,” concludes Guerra. If, however, the difference in chirality becomes too large, the faces disappear and the nanotubes take on the classic cylindrical shape.

The faces appear spontaneously depending on the characteristics of the material. Double-walled carbon nanotubes tend to form with a greater difference in internal and external chirality compared to boron nitride. Therefore, the former usually maintains a cylindrical shape that allows for less friction. In further studies, Guerra and colleagues intend to work directly on measuring the level of friction between nanotubes.

Here’s a link to and a citation for the paper,

Multiwalled nanotube faceting unravelled by Itai Leven, Roberto Guerra, Andrea Vanossi, Erio Tosatti, & Oded Hod. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.151 Published online 22 August 2016

This paper is behind a paywall.

Carbon nanotubes that can outperform silicon

According to a Sept. 2, 2016 news item on phys.org, researchers at the University of Wisconsin-Madison have produced carbon nanotube transistors that outperform state-of-the-art silicon transistors,

For decades, scientists have tried to harness the unique properties of carbon nanotubes to create high-performance electronics that are faster or consume less power—resulting in longer battery life, faster wireless communication and faster processing speeds for devices like smartphones and laptops.

But a number of challenges have impeded the development of high-performance transistors made of carbon nanotubes, tiny cylinders made of carbon just one atom thick. Consequently, their performance has lagged far behind semiconductors such as silicon and gallium arsenide used in computer chips and personal electronics.

Now, for the first time, University of Wisconsin-Madison materials engineers have created carbon nanotube transistors that outperform state-of-the-art silicon transistors.

Led by Michael Arnold and Padma Gopalan, UW-Madison professors of materials science and engineering, the team’s carbon nanotube transistors achieved current that’s 1.9 times higher than silicon transistors. …

A Sept. 2, 2016 University of Wisconsin-Madison news release (also on EurekAlert) by Adam Malecek, which originated the news item, describes the research in more detail and notes that the technology has been patented,

“This achievement has been a dream of nanotechnology for the last 20 years,” says Arnold. “Making carbon nanotube transistors that are better than silicon transistors is a big milestone. This breakthrough in carbon nanotube transistor performance is a critical advance toward exploiting carbon nanotubes in logic, high-speed communications, and other semiconductor electronics technologies.”

This advance could pave the way for carbon nanotube transistors to replace silicon transistors and continue delivering the performance gains the computer industry relies on and that consumers demand. The new transistors are particularly promising for wireless communications technologies that require a lot of current flowing across a relatively small area.

As some of the best electrical conductors ever discovered, carbon nanotubes have long been recognized as a promising material for next-generation transistors.

Carbon nanotube transistors should be able to perform five times faster or use five times less energy than silicon transistors, according to extrapolations from single nanotube measurements. The nanotube’s ultra-small dimension makes it possible to rapidly change a current signal traveling across it, which could lead to substantial gains in the bandwidth of wireless communications devices.

But researchers have struggled to isolate purely carbon nanotubes, which are crucial, because metallic nanotube impurities act like copper wires and disrupt their semiconducting properties — like a short in an electronic device.

The UW–Madison team used polymers to selectively sort out the semiconducting nanotubes, achieving a solution of ultra-high-purity semiconducting carbon nanotubes.

“We’ve identified specific conditions in which you can get rid of nearly all metallic nanotubes, where we have less than 0.01 percent metallic nanotubes,” says Arnold.

Placement and alignment of the nanotubes is also difficult to control.

To make a good transistor, the nanotubes need to be aligned in just the right order, with just the right spacing, when assembled on a wafer. In 2014, the UW–Madison researchers overcame that challenge when they announced a technique, called “floating evaporative self-assembly,” that gives them this control.

The nanotubes must make good electrical contacts with the metal electrodes of the transistor. Because the polymer the UW–Madison researchers use to isolate the semiconducting nanotubes also acts like an insulating layer between the nanotubes and the electrodes, the team “baked” the nanotube arrays in a vacuum oven to remove the insulating layer. The result: excellent electrical contacts to the nanotubes.

The researchers also developed a treatment that removes residues from the nanotubes after they’re processed in solution.

“In our research, we’ve shown that we can simultaneously overcome all of these challenges of working with nanotubes, and that has allowed us to create these groundbreaking carbon nanotube transistors that surpass silicon and gallium arsenide transistors,” says Arnold.

The researchers benchmarked their carbon nanotube transistor against a silicon transistor of the same size, geometry and leakage current in order to make an apples-to-apples comparison.

They are continuing to work on adapting their device to match the geometry used in silicon transistors, which get smaller with each new generation. Work is also underway to develop high-performance radio frequency amplifiers that may be able to boost a cellphone signal. While the researchers have already scaled their alignment and deposition process to 1 inch by 1 inch wafers, they’re working on scaling the process up for commercial production.

Arnold says it’s exciting to finally reach the point where researchers can exploit the nanotubes to attain performance gains in actual technologies.

“There has been a lot of hype about carbon nanotubes that hasn’t been realized, and that has kind of soured many people’s outlook,” says Arnold. “But we think the hype is deserved. It has just taken decades of work for the materials science to catch up and allow us to effectively harness these materials.”

The researchers have patented their technology through the Wisconsin Alumni Research Foundation.

Interestingly, at least some of the research was publicly funded according to the news release,

Funding from the National Science Foundation, the Army Research Office and the Air Force supported their work.

Will the public ever benefit financially from this research?

Next generation of power lines could be carbon nanotube-coated

This research was done at the Masdar Institute in Abu Dhabi of the United Arab Emirates. From a Sept. 1, 2016 news item on Nanowerk,

A Masdar Institute Assistant Professor may have brought engineers one step closer to developing the type of next-generation power lines needed to achieve sustainable and resilient electrical power grids.

Dr. Kumar Shanmugam, Assistant Professor of Materials and Mechanical Engineering, helped develop a novel coating made from carbon nanotubes that, when layered around an aluminum-conductor composite core (ACCC) transmission line, reduces the line’s operating temperature and significantly improves its overall transmission efficiency.

An Aug. 29, 2016 Masdar Institute news release by Erica Solomon, which originated the news item, provides more detail,

The coating is made from carbon nanostructures (CNS) – which are bundles of aligned carbon nanotubes that have exceptional mechanical and electrical properties – provided by the project’s sponsor, Lockheed Martin. The second component of the coating is an epoxy resin, which is the thick material used to protect things like appliances and electronics from damage.  Together, the CNS and epoxy resin help prevent power lines from overheating, increases their current carrying capacity (the amount of current that can flow through a transmission line), while also protecting them from damages associated with lightning strikes, ice and other environmental impacts.

The researchers found that by replacing traditional steel-core transmission lines with ACCC cables layered with a CNS-epoxy coating (referred to in the study as ACCC-CNS lines), the amount of aluminum used in an ACCC cable can be reduced by 25%, making the cable significantly lighter and cheaper to produce. The span length of a transmission line can also increase by 30%, which will make it easier to transmit electricity across longer distances while the amount of current the line can carry can increase by 40%.

“The coating helps to dissipate the heat generated in the conductor more efficiently through radiation and convection, thereby preventing the cable from overheating and enabling it to carry more current farther distances,” Dr. Kumar explained.

Ultimately, the purpose of the coating is to effectively eliminate the transmission line losses. Each year, anywhere from 5% to over 10% of the overall power generated in a power plant is lost in transmission and distribution lines. Most of this electrical energy is lost in the form of heat; as current runs through a conductor (the transmission line), the conductor heats up because it resists the flow of electrons to some extent – a phenomenon known as resistive Joule heating. Resistive Joule heating causes the energy that was moving the electrons forward to change into heat energy, which means some of the generated power gets converted into heat and lost to the surrounding environment instead of getting to its intended destination (like our homes and offices).

In addition to wasting energy, resistive Joule heating can lead to overheating, which can trigger a transmission line to “sag”, or physically droop low to the ground. Sagging power lines in turn can have catastrophic effects, including short circuits and power outages.

Efforts to reduce the problem of resistive heating and energy loss in power lines have led to significant improvements in transmission line technologies. For example, in 2002 ACCC transmission cables – which feature a carbon and glass-fiber reinforced composite core wrapped in aluminum conductor wires – were invented. The ACCC conductors are lighter and more heat-resistant than traditional steel-core cables, which means they can carry more current without overheating or sagging. Today, it is estimated that over 200 power and distribution networks use ACCC transmission cables.

While the advent of composite core cables marks the first major turning point in the development of energy-efficient transmission lines, Dr. Kumar’s CNS-epoxy coating may be the second significant advancement in the evolution of sustainable power lines.

The CNS-epoxy coating works by keeping the cable’s operating temperatures low. It does this by dissipating, any generated heat away from the conductor efficiently, thereby preventing further increase in temperature of the line and avoiding the trickle-effect that often leads to overheating.

The coating is layered twice in the ACCC cable – an outer layer, which dissipates the heat and protects the cable from environmental factors like lightning strikes and foreign object impact; and an inner layer, which protects the composite core from damage caused by stray radio frequency radiation generated by the electromagnetic pulse emanating from high electric current carrying aluminum conductor

The research team utilized a multi-physics modeling framework to analyze how the CNS-epoxy coating would influence the performance of ACCC transmission line. After fabricating the coating, they characterized it, which is a critical step to determine its mechanical, thermal and electrical properties. These properties were then used in the computational and theoretical models to evaluate and predict the coating’s performance. Finally, a design tool was developed and used to find the optimal combination of parameters (core diameter, span distance and sag) needed to reduce the cable’s weight, sag, and operating temperature while increasing its span distance and current carrying capacity.

Dr. Kumar’s innovative transmission line technology research comes at a pivotal time, when countries all over the world, including the UAE, are seeking ways to reduce their carbon footprint in a concerted effort to mitigate global climate change. Turning to energy-efficient power lines that waste less power and in turn produce less carbon dioxide emissions will be an obvious choice for nations devoted to greater sustainability.

Here’s a link to and a citation for the paper,

High-Ampacity Overhead Power Lines With Carbon Nanostructure–Epoxy Composites by V. S. N. Ranjith Kumar, S. Kumar, G. Pal, and Tushar Shah. J. Eng. Mater. Technol 138(4), 041018 (Aug 09, 2016) (9 pages) Paper No: MATS-15-1217; doi: 10.1115/1.4034095

This paper is behind a paywall.

Harvard University announced new Center on Nano-safety Research

The nano safety center at Harvard University (Massachusetts, US) is a joint center with the US National Institute of Environmental Health  Sciences according to an Aug. 29, 2016 news item on Nanowerk,

Engineered nanomaterials (ENMs)—which are less than 100 nanometers (one millionth of a millimeter) in diameter—can make the colors in digital printer inks pop and help sunscreens better protect against radiation, among many other applications in industry and science. They may even help prevent infectious diseases. But as the technology becomes more widespread, questions remain about the potential risks that ENMs may pose to health and the environment.

Researchers at the new Harvard-NIEHS [US National Institute of Environmental Health Sciences] Nanosafety Research Center at Harvard T.H. Chan School of Public Health are working to understand the unique properties of ENMs—both beneficial and harmful—and to ultimately establish safety standards for the field.

An Aug. 16, 2016 Harvard University press release, which originated the news item, provides more detail (Note: Links have been removed),

“We want to help nanotechnology develop as a scientific and economic force while maintaining safeguards for public health,” said Center Director Philip Demokritou, associate professor of aerosol physics at Harvard Chan School. “If you understand the rules of nanobiology, you can design safer nanomaterials.”

ENMs can enter the body through inhalation, ingestion, and skin contact, and toxicological studies have shown that some can penetrate cells and tissues and potentially cause biochemical damage. Because the field of nanoparticle science is relatively new, no standards currently exist for assessing the health risks of exposure to ENMs—or even for how studies of nano-biological interactions should be conducted.

Much of the work of the new Center will focus on building a fundamental understanding of why some ENMs are potentially more harmful than others. The team will also establish a “reference library” of ENMs, each with slightly varied properties, which will be utilized in nanotoxicology research across the country to assess safety. This will allow researchers to pinpoint exactly what aspect of an ENM’s properties may impact health. The researchers will also work to develop standardized methods for nanotoxicology studies evaluating the safety of nanomaterials.

The Center was established with a $4 million dollar grant from the National Institute of Environmental Health Science (NIEHS) last month, and is the only nanosafety research center to receive NIEHS funding for the next five years. It will also play a coordinating role with existing and future NIEHS nanotoxicology research projects nantionwide. Scientists from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), MIT, University of Maine, and University of Florida will collaborate on the new effort.

The Center builds on the existing Center for Nanotechnology and Nanotoxicology at Harvard Chan School, established by Demokritou and Joseph Brain, Cecil K. and Philip Drinker Professor of Environmental Physiology, in the School’s Department of Environmental Health in 2010.

A July 5, 2016 Harvard University press release announcing the $4M grant provides more information about which ENMs are to be studied,

The main focus of the new HSPH-NIEHS Center is to bring together  scientists from across disciplines- material science, chemistry, exposure assessment, risk assessment, nanotoxicology and nanobiology- to assess the potential  environmental Health and safety (EHS) implications of engineered nanomaterials (ENMs).

The $4 million dollar HSPH based Center  which is the only Nanosafety Research  Center to be funded by NIEHS this funding cycle, … The new HSPH-NIEHS Nanosafety Center builds upon the nano-related infrastructure in [the] collaborating Universities, developed over the past 10 years, which includes an inter-disciplinary research group of faculty, research staff and students, as well as state-of-the-art platforms for high throughput synthesis of ENMs, including metal and metal oxides, cutting edge 2D/3D ENMs such as CNTs [carbon nanotubes] and graphene, nanocellulose, and advanced nanocomposites, [emphasis mine] coupled with innovative tools to assess the fate and transport of ENMs in biological systems, statistical and exposure assessment tools, and novel in vitro and in vivo platforms for nanotoxicology research.

“Our mission is to integrate material/exposure/chemical sciences and nanotoxicology-nanobiology   to facilitate assessment of potential risks from emerging nanomaterials.  In doing so, we are bringing together the material synthesis/applications and nanotoxicology communities and other stakeholders including industry,   policy makers and the general public to maximize innovation and growth and minimize environmental and public health risks from nanotechnology”, quoted by  Dr Philip Demokritou, …

This effort certainly falls in line with the current emphasis on interdisciplinary research and creating standards and protocols for researching the toxicology of engineered nanomaterials.