Category Archives: electronics

Flexible electronics and Inorganic-based Laser Lift-off (ILLO) in Korea

Korean scientists are trying to make the process of creating flexible electronics easier according to a Nov. 25, 2014 news item on ScienceDaily,

Flexible electronics have been touted as the next generation in electronics in various areas, ranging from consumer electronics to bio-integrated medical devices. In spite of their merits, insufficient performance of organic materials arising from inherent material properties and processing limitations in scalability have posed big challenges to developing all-in-one flexible electronics systems in which display, processor, memory, and energy devices are integrated. The high temperature processes, essential for high performance electronic devices, have severely restricted the development of flexible electronics because of the fundamental thermal instabilities of polymer materials.

A research team headed by Professor Keon Jae Lee of the Department of Materials Science and Engineering at KAIST provides an easier methodology to realize high performance flexible electronics by using the Inorganic-based Laser Lift-off (ILLO).

The process is described in a Nov. 26, 2014 KAIST news release on ResearchSEA, which originated the news item (despite the confusion of the date, probably due to timezone differentials), provides more detail about the technique for ILLO,

The ILLO process involves depositing a laser-reactive exfoliation layer on rigid substrates, and then fabricating ultrathin inorganic electronic devices, e.g., high density crossbar memristive memory on top of the exfoliation layer. By laser irradiation through the back of the substrate, only the ultrathin inorganic device layers are exfoliated from the substrate as a result of the reaction between laser and exfoliation layer, and then subsequently transferred onto any kind of receiver substrate such as plastic, paper, and even fabric.

This ILLO process can enable not only nanoscale processes for high density flexible devices but also the high temperature process that was previously difficult to achieve on plastic substrates. The transferred device successfully demonstrates fully-functional random access memory operation on flexible substrates even under severe bending.

Professor Lee said, “By selecting an optimized set of inorganic exfoliation layer and substrate, a nanoscale process at a high temperature of over 1000 °C can be utilized for high performance flexible electronics. The ILLO process can be applied to diverse flexible electronics, such as driving circuits for displays and inorganic-based energy devices such as battery, solar cell, and self-powered devices that require high temperature processes.”

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

Flexible Crossbar-Structured Resistive Memory Arrays on Plastic Substrates via Inorganic-Based Laser Lift-Off by Seungjun Kim, Jung Hwan Son, Seung Hyun Lee, Byoung Kuk You, Kwi-Il Park, Hwan Keon Lee, Myunghwan Byun and Keon Jae Lee. Advanced Materials Volume 26, Issue 44, pages 7480–7487, November 26, 2014 Article first published online: 8 SEP 2014 DOI: 10.1002/adma.201402472

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Here’s an image the researchers have made available,

This photo shows the flexible RRAM device on a plastic substrate. Courtesy: KAIST

This photo shows the flexible RRAM device on a plastic substrate. Courtesy: KAIST

Finally, the research paper is behind a paywall.

Norway and degradable electronics

It’s a bit higgledy-piggledy but a Nov. 20, 2014 news item on Nanowerk highlights some work with degradable electronics taking place in Norway,

When the FM frequencies are removed in Norway in 2017, all old-fashioned radios will become obsolete, leaving the biggest collection of redundant electronics ever seen – a mountain of waste weighing something between 25,000 and 30,000 tonnes.

The same thing is happening with today’s mobile telephones, PCs and tablets, all of which are constantly being updated and replaced faster than the blink of an eye. The old devices end up on waste tips, and even though we in the west recover some materials for recycling, this is only a small proportion of the whole.

And nor does the future bode well with waste in mind. Technologists’ vision of the future is the “Internet of Things”. Electronics are currently printed onto plastics. All products are fitted with sensors designed to measure something, and to make it possible to talk to other devices around them. Davor Sutija is General Manager at the electronics firm Thin Film, and he predicts that in the course of a few years each of us will progress from having a single sensor to having between a hundred and a thousand. This in turn will mean that billions of devices with electronic bar codes will be released onto the market.

Researchers are now getting to grips with this problem. Their aim is to develop processes in which electronics are manufactured in such a way that their entire life cycle is controlled, including their ultimate disappearance.

A Nov. 20, 2014 article by Åse Dragland for the Gemini newsletter (also found as a Nov. 20, 2014 news release on SINTEF [Norwegian: Stiftelsen for industriell og teknisk forskning]), describes the inspiration for the work in Norway while pointing out some signficant differences from US researchers in the approach to creating a commercial application,

In New Orleans in the USA, researchers have made electronic circuits which they implant into surgical wounds following operations on rats. Each wound is sewn up and the electricity in the circuits then accelerates the healing process. After a few weeks, the electronics are dissolved by the body fluids, making it unnecessary to re-open the wound to remove them manually.

In Norway, researchers at SINTEF have now succeeded in making components containing magnesium circuits designed to transfer energy. These are soluble in water and disappear after a few hours.

“We make no secret of the fact that we are putting our faith in the research results coming out of the USA”, says Karsten Husby at SINTEF ICT. “The Americans have made amazing contributions both in relation to medical applications, and towards resolving the issue of waste. We want to try to find alternative approaches to the same problem”, he says.

The circuit containing the small components is printed on a silicon wafer. At only a few nanometres thick, the circuits are extremely thin, and this enables them to dissolve more effectively. Some of the circuit components are made of magnesium, others of silicon, and others of silicon with a magnesium additive.

But the journey to the researchers’ goal from their current position leaves them with more than enough work to do. Making the ultra-thin circuits is a challenge enough in itself, but they also have to find a “coating” or “film” which will act as a protective packaging around the circuits.

The Americans use silk as their coating material, but the Norwegians are not in favour of this. The silk used is made as part of a process which involves the substance lithium, which is banned at MiNaLab – the laboratory where the SINTEF researchers work.

“Lithium generates a technical problem for our lab”, says Geir Uri Jensen, “so we’re considering alternatives, including a variety of plastics”, he says. “In order to achieve this, we’ve brought in some materials scientists here at SINTEF who are very skilled in this field”, he says.

The nature of the coating must be tailored to the time at which the electronics are required to degrade. In some cases this is just one week – in others, four. For example, if the circuit package is designed to be used in seawater, and fitted with sensors for taking measurements from oil spills, the film must be made so that it remains in place for the weeks in which the measurements are being taken.

“When the external fluids penetrate to the “guts” inside the packaging, the circuits begin to degrade. The job must be completed before this happens”, says Karsten Husby.

Geir Uri Jensen makes a sketch and explains how the nano researchers use horizontal and vertical etching processes in the lab to deposit all the layers onto the silicon circuits. And then – how they have to etch and lift the circuit loose from the silicon wafer in order later to transfer it across to the film.

“This works well enough using sensors at full scale”, he says, “but when the wafers are as thin as this, things become more tricky”. Jensen shrugs. “Even if the angle is just a little off, the whole assembly will snap”, he says.

There’s no doubt that as the use of consumer electronics increases, so too does the need to remove obsolete electronic products. Just think of all the cheap electronics built into children’s toys which are thrown away every year.

The removal of “outdated electronics” can also be a very labour-intensive process. Every day, surgeons place implants fitted with sensors into our bodies in order to measure everything from blood pressure and pressure on the brain, to how our hip implants are working. Some weeks later they have to operate again in order to remove the electronics.

But not everyone is interested in the new technologies developing in this field. Electronics companies which manufacture circuits are more interested in selling their products than in investing in research that results in their products disappearing. And companies which rely on recycling for their revenues may regard these new ideas as a threat to their existence.
Eco-friendly electronics are on the way

“It’s important to make it clear that we’re not manufacturing a final product, but a demo that can show that an electronic component can be made with properties that make it degradable”, says Husby. “Our project is now in its second year, but we’ll need a partner active in the industry and more funding in the years ahead if we’re to meet our objectives. There’s no doubt that eco-friendly electronics is a field which will come into its own, also here in Norway. And we’ve made it our mission to reach our goals”, he says.

Here’s an image of dissolving electronic circuits made available by the researchers,

Electronic circuits can be implanted into surgical wounds and assist the healing process by accelerating wound closure. After a few weeks, the electronics are dissolved by the body fluids, making it unnecessary to re-open the wound to remove them manually. Photos: Werner Juvik/SINTEF - See more at: http://gemini.no/en/2014/11/tomorrows-degradable-electronics/#sthash.Erh1sZp2.dpuf

Electronic circuits can be implanted into surgical wounds and assist the healing process by accelerating wound closure. After a few weeks, the electronics are dissolved by the body fluids, making it unnecessary to re-open the wound to remove them manually. Photos: Werner Juvik/SINTEF – See more at: http://gemini.no/en/2014/11/tomorrows-degradable-electronics/#sthash.Erh1sZp2.dpuf

The researcher most associated with this kind of work is John Rogers at the University of Illinois at Urbana-Champaign and you can read more about biodegradable/dissolving electronics in a Sept. 27, 2012 article (open access) by Katherine Bourzac for Nature magazine. You can find more information about Thin Film Electronics or Thinfilm Electronics (mentioned in the third paragraph of the news item on Nanowerk) website here.

Super-capacitors on automobiles

Queensland University of Technology* (QUT; Australia) researchers are hopeful they can adapt supercapacitors in the form of a fine film tor use in electric vehicles making them more energy-efficient. From a Nov. 6, 2014 news item on ScienceDaily,

A car powered by its own body panels could soon be driving on our roads after a breakthrough in nanotechnology research by a QUT team.

Researchers have developed lightweight “supercapacitors” that can be combined with regular batteries to dramatically boost the power of an electric car.

The discovery was made by Postdoctoral Research Fellow Dr Jinzhang Liu, Professor Nunzio Motta and PhD researcher Marco Notarianni, from QUT’s Science and Engineering Faculty — Institute for Future Environments, and PhD researcher Francesca Mirri and Professor Matteo Pasquali, from Rice University in Houston, in the United States.

A Nov. 6, 2014 QUT news release, which originated the news item, describes supercapacitors, the research, and the need for this research in more detail,

The supercapacitors – a “sandwich” of electrolyte between two all-carbon electrodes – were made into a thin and extremely strong film with a high power density.

The film could be embedded in a car’s body panels, roof, doors, bonnet and floor – storing enough energy to turbocharge an electric car’s battery in just a few minutes.

“Vehicles need an extra energy spurt for acceleration, and this is where supercapacitors come in. They hold a limited amount of charge, but they are able to deliver it very quickly, making them the perfect complement to mass-storage batteries,” he said.

“Supercapacitors offer a high power output in a short time, meaning a faster acceleration rate of the car and a charging time of just a few minutes, compared to several hours for a standard electric car battery.”

Dr Liu said currently the “energy density” of a supercapacitor is lower than a standard lithium ion (Li-Ion) battery, but its “high power density”, or ability to release power in a short time, is “far beyond” a conventional battery.

“Supercapacitors are presently combined with standard Li-Ion batteries to power electric cars, with a substantial weight reduction and increase in performance,” he said.

“In the future, it is hoped the supercapacitor will be developed to store more energy than a Li-Ion battery while retaining the ability to release its energy up to 10 times faster – meaning the car could be entirely powered by the supercapacitors in its body panels.

“After one full charge this car should be able to run up to 500km – similar to a petrol-powered car and more than double the current limit of an electric car.”

Dr Liu said the technology would also potentially be used for rapid charges of other battery-powered devices.

“For example, by putting the film on the back of a smart phone to charge it extremely quickly,” he said.

The discovery may be a game-changer for the automotive industry, with significant impacts on financial, as well as environmental, factors.

“We are using cheap carbon materials to make supercapacitors and the price of industry scale production will be low,” Professor Motta said.

“The price of Li-Ion batteries cannot decrease a lot because the price of Lithium remains high. This technique does not rely on metals and other toxic materials either, so it is environmentally friendly if it needs to be disposed of.”

A Nov. 10, 2014 news item on Azonano describes the Rice University (Texas, US) contribution to this work,

Rice University scientist Matteo Pasquali and his team contributed to two new papers that suggest the nano-infused body of a car may someday power the car itself.

Rice supplied high-performance carbon nanotube films and input on the device design to scientists at the Queensland University of Technology in Australia for the creation of lightweight films containing supercapacitors that charge quickly and store energy. The inventors hope to use the films as part of composite car doors, fenders, roofs and other body panels to significantly boost the power of electric vehicles.

A Nov. 7, 2014 Rice University news release, which originated the news item, offers a few technical details about the film being proposed for use as a supercapacitor on car panels,

Researchers in the Queensland lab of scientist Nunzio Motta combined exfoliated graphene and entangled multiwalled carbon nanotubes combined with plastic, paper and a gelled electrolyte to produce the flexible, solid-state supercapacitors.

“Nunzio’s team is making important advances in the energy-storage area, and we were glad to see that our carbon nanotube film technology was able to provide breakthrough current collection capability to further improve their devices,” said Pasquali, a Rice professor of chemical and biomolecular engineering and chemistry. “This nice collaboration is definitely bottom-up, as one of Nunzio’s Ph.D. students, Marco Notarianni, spent a year in our lab during his Master of Science research period a few years ago.”

“We built on our earlier work on CNT films published in ACS Nano, where we developed a solution-based technique to produce carbon nanotube films for transparent electrodes in displays,” said Francesca Mirri, a graduate student in Pasquali’s research group and co-author of the papers. “Now we see that carbon nanotube films produced by the solution-processing method can be applied in several areas.”

As currently designed, the supercapacitors can be charged through regenerative braking and are intended to work alongside the lithium-ion batteries in electric vehicles, said co-author Notarianni, a Queensland graduate student.

“Vehicles need an extra energy spurt for acceleration, and this is where supercapacitors come in. They hold a limited amount of charge, but with their high power density, deliver it very quickly, making them the perfect complement to mass-storage batteries,” he said.

Because hundreds of film supercapacitors are used in the panel, the electric energy required to power the car’s battery can be stored in the car body. “Supercapacitors offer a high power output in a short time, meaning a faster acceleration rate of the car and a charging time of just a few minutes, compared with several hours for a standard electric car battery,” Notarianni said.

The researchers foresee such panels will eventually replace standard lithium-ion batteries. “In the future, it is hoped the supercapacitor will be developed to store more energy than an ionic battery while retaining the ability to release its energy up to 10 times faster – meaning the car would be powered by the supercapacitors in its body panels,” said Queensland postdoctoral researcher Jinzhang Liu.

Here’s an image of graphene infused with carbon nantoubes used in the supercapacitor film,

A scanning electron microscope image shows freestanding graphene film with carbon nanotubes attached. The material is part of a project to create lightweight films containing super capacitors that charge quickly and store energy. Courtesy of Nunzio Motta/Queensland University of Technology - See more at: http://news.rice.edu/2014/11/07/supercharged-panels-may-power-cars/#sthash.0RPsIbMY.dpuf

A scanning electron microscope image shows freestanding graphene film with carbon nanotubes attached. The material is part of a project to create lightweight films containing super capacitors that charge quickly and store energy. Courtesy of Nunzio Motta/Queensland University of Technology

Here are links to and citations for the two papers published by the researchers,

Graphene-based supercapacitor with carbon nanotube film as highly efficient current collector by Marco Notarianni, Jinzhang Liu, Francesca Mirri, Matteo Pasquali, and Nunzio Motta. Nanotechnology Volume 25 Number 43 doi:10.1088/0957-4484/25/43/435405

High performance all-carbon thin film supercapacitors by Jinzhang Liu, Francesca Mirri, Marco Notarianni, Matteo Pasquali, and Nunzio Motta. Journal of Power Sources Volume 274, 15 January 2015, Pages 823–830 DOI: 10.1016/j.jpowsour.2014.10.104

Both articles are behind paywalls.

One final note, Dexter Johnson provides some insight into issues with graphene-based supercapacitors and what makes this proposed application attractive in his Nov. 7, 2014 post on the Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website; Note: Links have been removed),

The hope has been that someone could make graphene electrodes for supercapacitors that would boost their energy density into the range of chemical-based batteries. The supercapacitors currently on the market have on average an energy density around 28 Wh/kg, whereas a Li-ion battery holds about 200Wh/kg. That’s a big gap to fill.

The research in the field thus far has indicated that graphene’s achievable surface area in real devices—the factor that determines how many ions a supercapacitor electrode can store, and therefore its energy density—is not any better than traditional activated carbon. In fact, it may not be much better than a used cigarette butt.

Though graphene may not help increase supercapacitors’ energy density, its usefulness in this application may lie in the fact that its natural high conductivity will allow superconductors to operate at higher frequencies than those that are currently on the market. Another likely benefit that graphene will yield comes from the fact that it can be structured and scaled down, unlike other supercapacitor materials.

I recommend reading Dexter’s commentary in its entirety.

*’University of Queensland’ corrected to “Queensland University of Technology’ on Nov. 10, 2014 at 1335 PST.

Toughening up your electronics: kevlar with a tungsten fibre coating

An upcoming presentation at the 61st annual AVS Conference (Nov. 9 – 14, 2014) features a fibre made of tungsten that when added to kevlar offers the possibility of ‘tough’ electronics. From an Oct. 31, 2014 news item on Nanowerk (Note: A link has been removed),

A group of North Carolina State University researchers is exploring novel ways to apply semiconductor industry processes to unique substrates, such as textiles and fabrics, to “weave together” multifunctional materials with distinct capabilities.

During the AVS 61st International Symposium & Exhibition, being held November 9-14, 2014, in Baltimore, Maryland, the researchers will describe how they were able to “weave” high-strength, highly conductive yarns made of tungsten metal on Kevlar — aka body armor material — by using atomic layer deposition (ALD), a process commonly used for producing memory and logic devices.

An Oct. 28, 2014 AVS: Science & Technology of Materials, Interfaces, and Processing news release on Newswire, which originated the news item provides more details about this multifunctional material and a good description of atomic layer deposition (ALD),

“As a substrate, Kevlar was intriguing to us because it’s capable of withstanding the relatively high temperature (220°C) required by the ALD deposition process,” explains Sarah Atanasov, a Ph.D. candidate in the Biomolecular Engineering Department at North Carolina State University. “Kevlar doesn’t begin to degrade until it reaches nearly 400°C.”

The group selected ALD as a process because it allows them to deposit highly conformal films on nonplanar surfaces with nanometer-thickness precision. “This ensures that the entire surface of the yarn — made of nearly 600 fibers, each 12 microns in diameter — is evenly coated,” said Atanasov.

How does the ALD process work? It’s actually a cyclical process, which begins by exposing the substrate’s surface to one gas-phase chemical, in this case tungsten hexafluoride (WF6), followed by removal of any unreacted material. This is chased with surface exposure to a second gas-phase chemical, silane (SiH4), after which any unreacted material is once again removed.

By the end of the ALD cycle, the two chemicals have reacted to produce tungsten. “This is a self-limited process, meaning that a single atomic layer is deposited during each cycle — in this case ~5.5 Angstroms per cycle,” Atanasov said. “The process can be cycled through a number of times to achieve any specifically desired thickness. As a bonus, ALD occurs in the gas phase, so it doesn’t require any solution processing and is considered to be a more sustainable deposition technique.”

While weaving together multiple fabrics to combine multiple capabilities certainly isn’t new, characteristics such as high strength, high conductivity, and flexibility are frequently regarded as being mutually exclusive — so concessions are often made to get the most important one.

The work by Atanasov and colleagues shows, however, that ALD of tungsten on Kevlar yields yarns that are highly flexible and highly conductive, around 2,000 S/cm (“Siemens per centimeter,” a common unit used for conductivity). The yards are also within 90 percent of their original prior-to-coating tensile strength.

“Introducing well-established processes from one area into a completely new field can lead to some very interesting and useful results,” Atanasov noted.

The group’s tungsten-on-Kevlar yarns are expected to find applications in multifunctional protective electronics materials for electromagnetic shielding and communications, as well as erosion-resistant antistatic fabrics for space and automated technologies.

Presentation #MS+PS+TF-ThA4, “Multifunctional Fabrics via Tungsten ALD on Kevlar,” authored by Sarah Atanasov, B. Kalanyan and G.N. Parsons, will be at 3:20 p.m. ET on Thursday, Nov. 13, 2014.

Atanasov recently published a paper about another kevlar project where she worked to enhance its ‘stab resistance’ with a titanium dioxide/aluminum mixture as Anisha Ratan notes in her Sept. 12, 2014 article (Oxide armour offers Kevlar better stab resistance)  (excerpt from Ratan’s article for the Royal Society; Note: Links have been removed),

Scientists in the US have synthesised an ultrathin inorganic bilayer coating for Kevlar that could improve its stab resistance by 30% and prove invaluable for military and first-responders requiring multi-threat protection clothes.

Developed in 1965 by Stephanie Kwolek at DuPont, poly(p-phenylene terephthalamide) (PPTA), or Kevlar, is a para-aramid synthetic fiber deriving its strength from interchain hydrogen bonding. It finds use in flexible energy and electronic systems, but is most commonly associated with bullet-proof body armour.

However, despite its anti-ballistic properties, it offers limited cut and stab protection. In a bid to overcome this drawback, Sarah Atanasov, from Gregory Parsons’ group at North Carolina State University, and colleagues, have developed a TiO2/Al2O3 bilayer that significantly enhances the cut resistance of Kevlar fibers. The coating is added to Kevlar by atomic layer deposition, a low temperature technique with nanoscale precision.

Unfortunately the team’s research paper is no longer open access but you can find a link to it from Ratan’s article.

Friendlier (halogen-free) lithium-ion batteries

An Oct. 24, 2014 news item on ScienceDaily mentions a greener type of lithium-ion battery from a theoretical (keep reading till you reach the first paragraph of the university news release) perspective,

Physics researchers at Virginia Commonwealth University have discovered that most of the electrolytes used in lithium-ion batteries — commonly found in consumer electronic devices — are superhalogens, and that the vast majority of these electrolytes contain toxic halogens.

At the same time, the researchers also found that the electrolytes in lithium-ion batteries (also known as Li-ion batteries) could be replaced with halogen-free electrolytes that are both nontoxic and environmentally friendly.

“The significance [of our findings] is that one can have a safer battery without compromising its performance,” said lead author Puru Jena, Ph.D., distinguished professor in the Department of Physics of the College of Humanities and Sciences. “The implication of our research is that similar strategies can also be used to design cathode materials in Li-ion batteries.”

An Oct. 24, 2014 Virginia Commonwealth University news release by Brian McNeill (also on EurekAlert), which originated the news item, describes the researchers’ hopes and the inspiration for this work,

“We hope that our theoretical prediction will stimulate experimentalists to synthesize halogen-free salts which will then lead manufacturers to use such salts in commercial applications,” he said.

The researchers also found that the procedure outlined for Li-ion batteries is equally valid for other metal-ion batteries, such as sodium-ion or magnesium-ion batteries.

Jena became interested in the topic several months ago when he saw a flyer on Li-ion batteries that mentioned the need for halogen-free electrolytes.

“I had not done any work on Li-ion batteries at the time, but I was curious to see what the current electrolytes are,” he said. “I found that the negative ions that make up the electrolytes are large and complex in nature and they contain one less electron than what is needed for electronic shell closure.”

Jena had already been working for more than five years on superhalogens, a class of molecules that mimic the chemistry of halogens but have electron affinities that are much larger than that of the halogen atoms.

“I knew of many superhalogen molecules that do not contain a single halogen atom,” he said. “My immediate thought was first to see if the anionic components of the current electrolytes are indeed superhalogens. And, if so, do the halogen-free superhalogens that we knew serve the purpose as halogen-free electrolytes? Our research proved that to be the case.”

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

Superhalogens as Building Blocks of Halogen-Free Electrolytes in Lithium-Ion Batteries by Dr. Santanab Giri, Swayamprabha Behera and Prof. Puru Jena. Angewandte Chemie, DOI: 10.1002/ange.201408648 Article first published online: 14 OCT 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

See-through medical sensors from the University of Wisconsin-Madison

This is quite the week for see-through medical devices based on graphene. A second team has developed a transparent sensor which could allow scientists to make observations of brain activity that are now impossible, according to an Oct. 20, 2014 University of Wisconsin-Madison news release (also on EurekAlert),

Neural researchers study, monitor or stimulate the brain using imaging techniques in conjunction with implantable sensors that allow them to continuously capture and associate fleeting brain signals with the brain activity they can see.

However, it’s difficult to see brain activity when there are sensors blocking the view.

“One of the holy grails of neural implant technology is that we’d really like to have an implant device that doesn’t interfere with any of the traditional imaging diagnostics,” says Justin Williams, the Vilas Distinguished Achievement Professor of biomedical engineering and neurological surgery at UW-Madison. “A traditional implant looks like a square of dots, and you can’t see anything under it. We wanted to make a transparent electronic device.”

The researchers chose graphene, a material gaining wider use in everything from solar cells to electronics, because of its versatility and biocompatibility. And in fact, they can make their sensors incredibly flexible and transparent because the electronic circuit elements are only 4 atoms thick—an astounding thinness made possible by graphene’s excellent conductive properties. “It’s got to be very thin and robust to survive in the body,” says Zhenqiang (Jack) Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor of electrical and computer engineering at UW-Madison. “It is soft and flexible, and a good tradeoff between transparency, strength and conductivity.”

Drawing on his expertise in developing revolutionary flexible electronics, he, Williams and their students designed and fabricated the micro-electrode arrays, which—unlike existing devices—work in tandem with a range of imaging technologies. “Other implantable micro-devices might be transparent at one wavelength, but not at others, or they lose their properties,” says Ma. “Our devices are transparent across a large spectrum—all the way from ultraviolet to deep infrared.”

The transparent sensors could be a boon to neuromodulation therapies, which physicians increasingly are using to control symptoms, restore function, and relieve pain in patients with diseases or disorders such as hypertension, epilepsy, Parkinson’s disease, or others, says Kip Ludwig, a program director for the National Institutes of Health neural engineering research efforts. “Despite remarkable improvements seen in neuromodulation clinical trials for such diseases, our understanding of how these therapies work—and therefore our ability to improve existing or identify new therapies—is rudimentary.”

Currently, he says, researchers are limited in their ability to directly observe how the body generates electrical signals, as well as how it reacts to externally generated electrical signals. “Clear electrodes in combination with recent technological advances in optogenetics and optical voltage probes will enable researchers to isolate those biological mechanisms. This fundamental knowledge could be catalytic in dramatically improving existing neuromodulation therapies and identifying new therapies.”

The advance aligns with bold goals set forth in President Barack Obama’s BRAIN (Brain Research through Advancing Innovative Neurotechnologies) Initiative. Obama announced the initiative in April 2013 as an effort to spur innovations that can revolutionize understanding of the brain and unlock ways to prevent, treat or cure such disorders as Alzheimer’s and Parkinson’s disease, post-traumatic stress disorder, epilepsy, traumatic brain injury, and others.

The UW-Madison researchers developed the technology with funding from the Reliable Neural-Interface Technology program at the Defense Advanced Research Projects Agency.

While the researchers centered their efforts around neural research, they already have started to explore other medical device applications. For example, working with researchers at the University of Illinois-Chicago, they prototyped a contact lens instrumented with dozens of invisible sensors to detect injury to the retina; the UIC team is exploring applications such as early diagnosis of glaucoma.

Here’s an image of the see-through medical implant,

Caption: A blue light shines through a clear implantable medical sensor onto a brain model. See-through sensors, which have been developed by a team of University of Wisconsin Madison engineers, should help neural researchers better view brain activity. Credit: Justin Williams research group

Caption: A blue light shines through a clear implantable medical sensor onto a brain model. See-through sensors, which have been developed by a team of University of Wisconsin Madison engineers, should help neural researchers better view brain activity.
Credit: Justin Williams research group

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

Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications by Dong-Wook Park, Amelia A. Schendel, Solomon Mikael, Sarah K. Brodnick, Thomas J. Richner, Jared P. Ness, Mohammed R. Hayat, Farid Atry, Seth T. Frye, Ramin Pashaie, Sanitta Thongpang, Zhenqiang Ma, & Justin C. Williams. Nature Communications 5, Article number: 5258 doi:10.1038/ncomms6258 Published
20 October 2014

This is an open access paper.

DARPA (US Defense Advanced Research Projects Agency), which funds this work at the University of Wisconsin-Madison, has also provided an Oct. 20, 2014 news release (also published an an Oct. 27, 2014 news item on Nanowerk) describing this research from the military perspective, which may not be what you might expect. First, here’s a description of the DARPA funding programme underwriting this research, from DARPA’s Reliable Neural-Interface Technology (RE-NET) webpage,

Advancing technology for military uniforms, body armor and equipment have saved countless lives of our servicemembers injured on the battlefield.  Unfortunately, many of those survivors are seriously and permanently wounded, with unprecedented rates of limb loss and traumatic brain injury among our returning soldiers. This crisis has motivated great interest in the science of and technology for restoring sensorimotor functions lost to amputation and injury of the central nervous system. For a decade now, DARPA has been leading efforts aimed at ‘revolutionizing’ the state-of-the-art in prosthetic limbs, recently debuting 2 advanced mechatronic limbs for the upper extremity. These new devices are truly anthropomorphic and capable of performing dexterous manipulation functions that finally begin to approach the capabilities of natural limbs. However, in the absence of a high bandwidth, intuitive interface for the user, these limbs will never achieve their full potential in improving the quality of life for the wounded soldiers that could benefit from this advanced technology.

DARPA created the Reliable Neural-Interface Technology (RE-NET) program in 2010 to directly address the need for high performance neural interfaces to control dexterous functions made possible with advanced prosthetic limbs.  Specifically, RE-NET seeks to develop the technologies needed to reliably extract information from the nervous system, and to do so at a scale and rate necessary to control many degree-of-freedom (DOF) machines, such as high-performance prosthetic limbs. Prior to the DARPA RE-NET program, all existing methods to extract neural control signals were inadequate for amputees to control high-performance prostheses, either because the level of extracted information was too low or the functional lifetime was too short. However, recent technological advances create new opportunities to solve both of these neural-interface problems. For example, it is now feasible to develop high-resolution peripheral neuromuscular interfaces that increase the amount of information obtained from the peripheral nervous system.  Furthermore, advances in cortical microelectrode technologies are extending the durability of neural signals obtained from the brain, making it possible to create brain-controlled prosthetics that remain useful over the full lifetime of the patient.

Graphene used to create electrodes one atom thick and transparent for brain research applications

It’s usually a ‘John Rogers (at the University of Illinois)’ story when there’s mention of transparent electronic devices but not this time. In an Oct. 20, 2014 news item on ScienceDaily, the University of Pennsylvania’s researchers are in the spotlight,

Researchers from the Perelman School of Medicine and School of Engineering at the University of Pennsylvania and The Children’s Hospital of Philadelphia have used graphene — a two-dimensional form of carbon only one atom thick — to fabricate a new type of microelectrode that solves a major problem for investigators looking to understand the intricate circuitry of the brain.

Pinning down the details of how individual neural circuits operate in epilepsy and other neurological disorders requires real-time observation of their locations, firing patterns, and other factors, using high-resolution optical imaging and electrophysiological recording. But traditional metallic microelectrodes are opaque and block the clinician’s view and create shadows that can obscure important details. In the past, researchers could obtain either high-resolution optical images or electrophysiological data, but not both at the same time.

The Center for NeuroEngineering and Therapeutics (CNT), under the leadership of senior author Brian Litt, PhD, has solved this problem with the development of a completely transparent graphene microelectrode that allows for simultaneous optical imaging and electrophysiological recordings of neural circuits. [emphasis mine] Their work was published this week in Nature Communications.

An Oct. 20, 2014 University of Pennsylvania news release (also on EurekAlert), which originated the news item, further describes the research,

“There are technologies that can give very high spatial resolution such as calcium imaging; there are technologies that can give high temporal resolution, such as electrophysiology, but there’s no single technology that can provide both,” says study co-first-author Duygu Kuzum, PhD. Along with co-author Hajime Takano, PhD, and their colleagues, Kuzum notes that the team developed a neuroelectrode technology based on graphene to achieve high spatial and temporal resolution simultaneously.

Aside from the obvious benefits of its transparency, graphene offers other advantages: “It can act as an anti-corrosive for metal surfaces to eliminate all corrosive electrochemical reactions in tissues,” Kuzum says. “It’s also inherently a low-noise material, which is important in neural recording because we try to get a high signal-to-noise ratio.”

While previous efforts have been made to construct transparent electrodes using indium tin oxide, they are expensive and highly brittle, making that substance ill-suited for microelectrode arrays. “Another advantage of graphene is that it’s flexible, so we can make very thin, flexible electrodes that can hug the neural tissue,” Kuzum notes.

In the study, Litt, Kuzum, and their colleagues performed calcium imaging of hippocampal slices in a rat model with both confocal and two-photon microscopy, while also conducting electrophysiological recordings. On an individual cell level, they were able to observe temporal details of seizures and seizure-like activity with very high resolution. The team also notes that the single-electrode techniques used in the Nature Communications study could be easily adapted to study other larger areas of the brain with more expansive arrays.

The graphene microelectrodes developed could have wider application. “They can be used in any application that we need to record electrical signals, such as cardiac pacemakers or peripheral nervous system stimulators,” says Kuzum. Because of graphene’s nonmagnetic and anti-corrosive properties, these probes “can also be a very promising technology to increase the longevity of neural implants.” Graphene’s nonmagnetic characteristics also allow for safe, artifact-free MRI reading, unlike metallic implants.

Kuzum emphasizes that the transparent graphene microelectrode technology was achieved through an interdisciplinary effort of CNT and the departments of Neuroscience, Pediatrics, and Materials Science at Penn and the division of Neurology at CHOP.

Ertugrul Cubukcu’s lab at Materials Science and Engineering Department helped with the graphene processing technology used in fabricating flexible transparent neural electrodes, as well as performing optical and materials characterization in collaboration with Euijae Shim and Jason Reed. The simultaneous imaging and recording experiments involving calcium imaging with confocal and two photon microscopy was performed at Douglas Coulter’s Lab at CHOP with Hajime Takano. In vivo recording experiments were performed in collaboration with Halvor Juul in Marc Dichter’s Lab. Somatasensory stimulation response experiments were done in collaboration with Timothy Lucas’s Lab, Julius De Vries, and Andrew Richardson.

As the technology is further developed and used, Kuzum and her colleagues expect to gain greater insight into how the physiology of the brain can go awry. “It can provide information on neural circuits, which wasn’t available before, because we didn’t have the technology to probe them,” she says. That information may include the identification of specific marker waveforms of brain electrical activity that can be mapped spatially and temporally to individual neural circuits. “We can also look at other neurological disorders and try to understand the correlation between different neural circuits using this technique,” she says.

It’s fascinating work and I hope it’s helpful but I can’t help noticing that these researchers, in common with most, tend to view the brain or whatever body part they’re examining in isolation from the rest of the body, whatever species is being examined. The answers as to why there are brain disorders and diseases may not lie wholly within the brain itself but within the totality of the organism in which the brain resides, i.e., the body. That reservation aside, there’s a link to and a citation for the research paper,

Transparent and flexible low noise graphene electrodes for simultaneous electrophysiology and neuroimaging by Duygu Kuzum, Hajime Takano, Euijae Shim, Jason C. Reed, Halvor Juul, Andrew G. Richardson, Julius de Vries, Hank Bink, Marc A. Dichter, Timothy H. Lucas, Douglas A. Coulter, Ertugrul Cubukcu, & Brian Litt. Nature Communications 5, Article number: 5259 doi:10.1038/ncomms6259 Published 20 October 2014

This paper is behind a paywall but there is a free preview available through ReadCube Access.

‘Genius’ grant (MacArthur Fellowship) for reseacher Mark Hersam and his work on carbon nanotubes and the next generation of electronics

It took a few minutes to figure out why Mark Hersam, professor at Northwestern University (Chicago, Illinois, US) is being featured in an Oct. 21, 2014 news item on Nanowerk,

One of the longstanding problems of working with nanomaterials–substances at the molecular and atomic scale–is controlling their size. When their size changes, their properties also change. This suggests that uniform control over size is critical in order to use them reliably as components in electronics.

Put another way, “if you don’t control size, you will have inhomogeneity in performance,” says Mark Hersam. “You don’t want some of your cell phones to work, and others not.”

Hersam, a professor of materials science engineering, chemistry and medicine at Northwestern University, has developed a method to separate nanomaterials by size, therefore providing a consistency in properties otherwise not available. Moreover, the solution came straight from the life sciences–biochemistry, in fact.

The technique, known as density gradient ultracentrifugation, is a decades-old process used to separate biomolecules. The National Science Foundation (NSF)-funded scientist theorized correctly that he could adapt it to separate carbon nanotubes, rolled sheets of graphene (a single atomic layer of hexagonally bonded carbon atoms), long recognized for their potential applications in computers and tablets, smart phones and other portable devices, photovoltaics, batteries and bioimaging.

The technique has proved so successful that Hersam and his team now hold two dozen pending or issued patents, and in 2007 established their own company, NanoIntegris, jump-started with a $150,000 NSF small business grant. The company has been able to scale up production by 10,000-fold, and currently has 700 customers in 40 countries.
“We now have the capacity to produce ten times the worldwide demand for this material,” Hersam says.

NSF supports Hersam with a $640,000 individual investigator grant awarded in 2010 for five years. Also, he directs Northwestern’s Materials Research Science and Engineering Center (MRSEC), which NSF funds, including support for approximately 30 faculty members/researchers.

Hersam also is a recent recipient of one of this year’s prestigious MacArthur fellowships, a $625,000 no-strings-attached award, popularly known as a “genius” grant. [emphases mine] These go to talented individuals who have shown extraordinary originality and dedication in their fields, and are meant to encourage beneficiaries to freely explore their interests without fear of risk-taking.

An Oct. 20, 2014 US National Science Foundation Discoveries article by Marlene Cimons, which originated the news item, describes Hersam’s research and his hopes for it in more detail,

The carbon nanotubes separation process, which Hersam developed, begins with a centrifuge tube. Into that, “we load a water based solution and introduce an additive which allows us to tune the buoyant density of the solution itself,” he explains.

“What we create is a gradient in the buoyant density of the aqueous solution, with low density at the top and high density at the bottom,” he continues. “We then load the carbon nanotubes and put it into the centrifuge, which drives the nanotubes through the gradient. The nanotubes move through the gradient until their density matches that of the gradient. The result is that the nanotubes form separated bands in the centrifuge tube by density. Since the density of the nanotube is a function of its diameter, this method allows separation by diameter.”

One property that distinguishes these materials from traditional semiconductors like silicon is that they are mechanically flexible. “Carbon nanotubes are highly resilient,” Hersam says. “That allows us to integrate electronics on flexible substrates, like clothing, shoes, and wrist bands for real time monitoring of biomedical diagnostics and athletic performance. These materials have the right combination of properties to realize wearable electronics.”

He and his colleagues also are working on energy technologies, such as solar cells and batteries “that can improve efficiency and reduce the cost of solar cells, and increase the capacity and reduce the charging time of batteries,” he says. “The resulting batteries and solar cells are also mechanically flexible, and thus can be integrated with flexible electronics.”

They likely even will prove waterproof. “It turns out that carbon nanomaterials are hydrophobic, so water will roll right off of them,” he says.

A Sept. 17, 2014 Northwestern University news release congratulates Hersam on his award while describing his response to the news and providing more information about his work as a researcher and teacher (Note: Links have been removed),

The phone call from the John D. and Catherine T. MacArthur Foundation delivering the very good news was so out of the blue that Hersam initially thought it was a joke.

“Then I went into shock, and, I think, to some extent I remain in shock,” said Hersam, who received the call in his Cook Hall office. “As time has gone on, I’ve appreciated, of course, that it’s a great honor and, more importantly, a great opportunity.”

A dedicated and popular teacher, Hersam is the Bette and Neison Harris Chair in Teaching Excellence and professor of materials science and engineering at the McCormick School of Engineering and Applied Science.

“There are very few awards that provide unrestricted resources, and this one does. No strings attached,” he said. “That’s a great opportunity for a researcher — to have that level of freedom.”

Hersam is one of 21 new MacArthur Fellows recognized today (Sept. 17) by the MacArthur Foundation for “extraordinary originality and dedication in their creative pursuits and a marked capacity for self-direction.”

“I am very grateful and thankful to the MacArthur Foundation, to current and previous members of my research group and to my colleagues and collaborators over the years,” Hersam said. “Scientific research is a team effort.”

Hersam views his principal job as that of an educator — a role in which he can have more impact on unsolved problems by harnessing the minds of hundreds of young scientists and engineers.

“I love to teach in the classroom, but I also believe that scientific research is a vehicle for teaching,” Hersam said. “Research exposes students to difficult unsolved problems, forcing them to be creative. I want them to come up with truly new ideas, not just regurgitate established concepts.”

Hersam, who joined Northwestern in 2000, also is professor of chemistry in the Weinberg College of Arts and Sciences, professor of medicine at the Northwestern University Feinberg School of Medicine and director of Northwestern’s Materials Research Center.

Taking an interdisciplinary approach that draws on techniques from materials science, physics, engineering and chemistry, Hersam has established himself as a leading experimentalist in the area of hybrid organic-inorganic materials, with a focus on the study of the electrical and optical properties of carbon and related nanomaterials.

Hersam and his research lab have been working primarily with carbon nanotubes and graphene, but the support of the MacArthur award will allow the lab to diversify its materials set to other elements in the periodic table.

Earlier this year Hersam testified before U.S. Congress to push for “coordinated, predictable and sustained federal funding” for nanotechnology research and development.

The MacArthur Foundation’s website hosts a video on its ‘Mark Hersam’ webpage,

Interestingly, Hersam, in the video, describes a carbon nanotube as a rolled up sheet of graphene (it’s also described that way on the Foundation’s ‘Hersam’ webpage),

Graphene, a single atomic layer of hexagonally bonded carbon atoms, and carbon nanotubes, rolled sheets of graphene in single or multiple layers, have long been recognized for their potential applications in electronics, photovoltaics, batteries, and bioimaging.

It’s a good way of describing carbon nanotubes but the odd thing is that carbon nanotubes were discovered in 1991 (Timeline of carbon nanotubes entry on Wikipedia and in The History of Carbon Nanotubes on nanogloss.com) before graphene was first isolated in 2004 (my Oct. 7, 2010 posting).

Bendable, stretchable, light-weight, and transparent: a new competitor in the competition for ‘thinnest electric generator’

An Oct. 15, 2014 Columbia University (New York, US) press release (also on EurekAlert), describes another contender for the title of the world’s thinnest electric generator,

Researchers from Columbia Engineering and the Georgia Institute of Technology [US] report today [Oct. 15, 2014] that they have made the first experimental observation of piezoelectricity and the piezotronic effect in an atomically thin material, molybdenum disulfide (MoS2), resulting in a unique electric generator and mechanosensation devices that are optically transparent, extremely light, and very bendable and stretchable.

In a paper published online October 15, 2014, in Nature, research groups from the two institutions demonstrate the mechanical generation of electricity from the two-dimensional (2D) MoS2 material. The piezoelectric effect in this material had previously been predicted theoretically.

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

Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics by Wenzhuo Wu, Lei Wang, Yilei Li, Fan Zhang, Long Lin, Simiao Niu, Daniel Chenet, Xian Zhang, Yufeng Hao, Tony F. Heinz, James Hone, & Zhong Lin Wang. Nature (2014) doi:10.1038/nature13792 Published online 15 October 2014

This paper is behind a paywall. There is a free preview available with ReadCube Access.

Getting back to the Columbia University press release, it offers a general description of piezoelectricity and some insight into this new research on molybdenum disulfide,

Piezoelectricity is a well-known effect in which stretching or compressing a material causes it to generate an electrical voltage (or the reverse, in which an applied voltage causes it to expand or contract). But for materials of only a few atomic thicknesses, no experimental observation of piezoelectricity has been made, until now. The observation reported today provides a new property for two-dimensional materials such as molybdenum disulfide, opening the potential for new types of mechanically controlled electronic devices.

“This material—just a single layer of atoms—could be made as a wearable device, perhaps integrated into clothing, to convert energy from your body movement to electricity and power wearable sensors or medical devices, or perhaps supply enough energy to charge your cell phone in your pocket,” says James Hone, professor of mechanical engineering at Columbia and co-leader of the research.

“Proof of the piezoelectric effect and piezotronic effect adds new functionalities to these two-dimensional materials,” says Zhong Lin Wang, Regents’ Professor in Georgia Tech’s School of Materials Science and Engineering and a co-leader of the research. “The materials community is excited about molybdenum disulfide, and demonstrating the piezoelectric effect in it adds a new facet to the material.”

Hone and his research group demonstrated in 2008 that graphene, a 2D form of carbon, is the strongest material. He and Lei Wang, a postdoctoral fellow in Hone’s group, have been actively exploring the novel properties of 2D materials like graphene and MoS2 as they are stretched and compressed.

Zhong Lin Wang and his research group pioneered the field of piezoelectric nanogenerators for converting mechanical energy into electricity. He and postdoctoral fellow Wenzhuo Wu are also developing piezotronic devices, which use piezoelectric charges to control the flow of current through the material just as gate voltages do in conventional three-terminal transistors.

There are two keys to using molybdenum disulfide for generating current: using an odd number of layers and flexing it in the proper direction. The material is highly polar, but, Zhong Lin Wang notes, so an even number of layers cancels out the piezoelectric effect. The material’s crystalline structure also is piezoelectric in only certain crystalline orientations.

For the Nature study, Hone’s team placed thin flakes of MoS2 on flexible plastic substrates and determined how their crystal lattices were oriented using optical techniques. They then patterned metal electrodes onto the flakes. In research done at Georgia Tech, Wang’s group installed measurement electrodes on samples provided by Hone’s group, then measured current flows as the samples were mechanically deformed. They monitored the conversion of mechanical to electrical energy, and observed voltage and current outputs.

The researchers also noted that the output voltage reversed sign when they changed the direction of applied strain, and that it disappeared in samples with an even number of atomic layers, confirming theoretical predictions published last year. The presence of piezotronic effect in odd layer MoS2 was also observed for the first time.

“What’s really interesting is we’ve now found that a material like MoS2, which is not piezoelectric in bulk form, can become piezoelectric when it is thinned down to a single atomic layer,” says Lei Wang.

To be piezoelectric, a material must break central symmetry. A single atomic layer of MoS2 has such a structure, and should be piezoelectric. However, in bulk MoS2, successive layers are oriented in opposite directions, and generate positive and negative voltages that cancel each other out and give zero net piezoelectric effect.

“This adds another member to the family of piezoelectric materials for functional devices,” says Wenzhuo Wu.

In fact, MoS2 is just one of a group of 2D semiconducting materials known as transition metal dichalcogenides, all of which are predicted to have similar piezoelectric properties. These are part of an even larger family of 2D materials whose piezoelectric materials remain unexplored. Importantly, as has been shown by Hone and his colleagues, 2D materials can be stretched much farther than conventional materials, particularly traditional ceramic piezoelectrics, which are quite brittle.

The research could open the door to development of new applications for the material and its unique properties.

“This is the first experimental work in this area and is an elegant example of how the world becomes different when the size of material shrinks to the scale of a single atom,” Hone adds. “With what we’re learning, we’re eager to build useful devices for all kinds of applications.”

Ultimately, Zhong Lin Wang notes, the research could lead to complete atomic-thick nanosystems that are self-powered by harvesting mechanical energy from the environment. This study also reveals the piezotronic effect in two-dimensional materials for the first time, which greatly expands the application of layered materials for human-machine interfacing, robotics, MEMS, and active flexible electronics.

I see there’s a reference in that last paragraph to “harvesting mechanical energy from  the environment.” I’m not sure what they mean by that but I have written a few times about harvesting biomechanical energy. One of my earliest pieces is a July 12, 2010 post which features work by Zhong Lin Wang on harvesting energy from heart beats, blood flow, muscle stretching, or even irregular vibrations. One of my latest pieces is a Sept. 17, 2014 post about some work in Canada on harvesting energy from the jaw as you chew.

A final note, Dexter Johnson discusses this work in an Oct. 16, 2014 post on the Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website).

Replacing copper wire in motors?

Finnish researchers at Lappeenranta University of Technology (LUT) believe it may be possible to replace copper wire used in motors with spun carbon nanotubes. From an Oct. 15, 2014 news item on Azonano,

Lappeenranta University of Technology (LUT) introduces the first electrical motor applying carbon nanotube yarn. The material replaces copper wires in windings. The motor is a step towards lightweight, efficient electric drives. Its output power is 40 W and rotation speed 15000 rpm.

Aiming at upgrading the performance and energy efficiency of electrical machines, higher-conductivity wires are searched for windings. Here, the new technology may revolutionize the industry. The best carbon nanotubes (CNTs) demonstrate conductivities far beyond the best metals; CNT windings may have double the conductivity of copper windings.

”If we keep the design parameters unchanged only replacing copper with carbon nanotube yarns, the Joule losses in windings can be reduced to half of present machine losses. By lighter and more ecological CNT yarn, we can reduce machine dimensions and CO2 emissions in manufacturing and operation. Machines could also be run in higher temperatures,” says Professor Pyrhönen [Juha Pyrhönen], leading the prototype design at LUT.

An Oct. ??, 2014 (?) LUT press release, which originated the news item, further describes the work,

Traditionally, the windings in electrical machines are made of copper, which has the second best conductivity of metals at room temperature. Despite the high conductivity of copper, a large proportion of the electrical machine losses occur in the copper windings. For this reason, the Joule losses are often referred to as copper losses. The carbon nanotube yarn does not have a definite upper limit for conductivity (e.g. values of 100 MS/m have already been measured).

According to Pyrhönen, the electrical machines are so ubiquitous in everyday life that we often forget about their presence. In a single-family house alone there can be tens of electrical machines in various household appliances such as refrigerators, washing machines, hair dryers, and ventilators.

“In the industry, the number of electrical motors is enormous: there can be up to tens of thousands of motors in a single process industry unit. All these use copper in the windings. Consequently, finding a more efficient material to replace the copper conductors would lead to major changes in the industry,” tells Professor Pyrhönen.

There are big plans for this work according to the press release,

The prototype motor uses carbon nanotube yarns spun and converted into an isolated tape by a Japanese-Dutch company Teijin Aramid, which has developed the spinning technology in collaboration with Rice University, the USA. The industrial applications of the new material are still in their infancy; scaling up the production capacity together with improving the yarn performance will facilitate major steps in the future, believes Business Development Manager Dr. Marcin Otto from Teijin Aramid, agreeing with Professor Pyrhönen.

“There is a significant improvement potential in the electrical machines, but we are now facing the limits of material physics set by traditional winding materials. Superconductivity appears not to develop to such a level that it could, in general, be applied to electrical machines. Carbonic materials, however, seem to have a pole position: We expect that in the future, the conductivity of carbon nanotube yarns could be even three times the practical conductivity of copper in electrical machines. In addition, carbon is abundant while copper needs to be mined or recycled by heavy industrial processes.”

The researchers have produced this video about their research,

There’s a reference to some work done at Rice University (Texas, US) with Teijin Armid (Japanese-Dutch company) and Technion Institute (Israel) with spinning carbon nanotubes into threads that look like black cotton (you’ll see the threads in the video). It’s this work that has made the latest research in Finland possible. I have more about the the Rice/Teijin Armid/Technion CNT project in my Jan. 11, 2013 posting, Prima donna of nanomaterials (carbon nanotubes) tamed by scientists at Rice University (Texas, US), Teijin Armid (Dutch/Japanese company), and Technion Institute (based in Israel).