Category Archives: electronics

Quantum dots, televisions, and a counter-intuitive approach to environmental issues

There’s a very interesting Jan. 8, 2015 essay by Dr. Andrew Maynard, being hosted on Nanowerk, about the effects that quantum dot televisions could have on the environment (Note: A link has been removed),

Earlier this week, The Conversation reported that, “The future is bright, the future is … quantum dot televisions”. And judging by the buzz coming from this week’s annual Consumer Electronics Show (CES) that’s right – the technology is providing manufacturers with a cheap and efficient way of producing the next generation of brilliant, high-definition TV screens.

But the quantum dots in these displays also use materials and technologies – including engineered nanoparticles and the heavy metal cadmium – that have been a magnet for health and environmental concerns. Will the dazzling pictures this technology allow blind us to new health and environmental challenges, or do their benefits outweigh the potential risks?

If I understand things rightly, cadmium is toxic at both the macroscale and the nanoscale and Andrew goes on to describe quantum dots (cadmium at the nanoscale) and the problem they could present in his Jan. 7, 2015 essay on The Conversation,also hosted by Nanowerk, (Note: Link have been removed),

Quantum dots are a product of the emerging field of nanotechnology. They are made of nanometer-sized particles of a semiconducting material – often cadmium selenide. About 2,000 to 20,000 times smaller than the width of a single human hair, they’re designed to absorb light of one color and emit it as another color – to fluoresce. This property makes them particularly well-suited for use in products like tablets and TVs that need bright, white, uniform backlights.

… What is unique about quantum dots is that the color of the emitted light can be modified by simply changing the size of the quantum dot particles. And because this color-shifting is a physical phenomenon, quantum dots far outperform their chemical counterparts in brightness, color and durability.

Unfortunately, the heavy metal cadmium used in the production of many quantum dots is a health and environmental hazard.

On top of this, the potential health and environmental impacts of engineered nanoparticles like quantum dots have been raising concerns with toxicologists and regulators for over a decade now. Research has shown that the size, shape and surface properties of some particles influence the harm they are capable of causing in humans and the environment; smaller particles are often more toxic than their larger counterparts. That said, this is an area where scientific understanding is still developing.

Together, these factors would suggest caution is warranted in adopting quantum dot technologies. Yet taken in isolation they are misleading.

The essay describes the risk factors for various sectors (Note: A link has been removed),

The quantum dots currently being used in TVs are firmly embedded in the screens – usually enclosed behind multiple layers of glass and plastic. As a result, the chances of users being exposed to them during normal operation are pretty much nil.

The situation is potentially different during manufacturing, when there is a chance that someone could be inadvertently exposed to these nanoscopic particles. Scenarios like this have led to agencies like the US National Institute for Occupational Safety and Health taking a close look at safety when working with nanoparticles. While the potential risks are not negligible, good working practices are effective at reducing or eliminating potentially harmful exposures.

End-of-life disposal raises additional concerns. While the nanoparticles are likely to remain firmly embedded within a trashed TV’s screen, the toxic materials they contain, including cadmium, could well be released into the environment. Cadmium is certainly a health and environmental issue with poorly regulated e-waste disposal and recycling. However, when appropriate procedures are used, exposures should be negligible.

It seems quantum dot televisions impose a smaller burden than their cousins on the environment,

Although it seems counter-intuitive, analysis by the company that was made available to the EPA [US Environmental Protection Agency] showed QD Vision’s products lead to a net decrease in environmental cadmium releases compared to conventional TVs. Cadmium is one of the pollutants emitted from coal-fired electrical power plants. Because TVs using the company’s quantum dots use substantially less power than their non-quantum counterparts, the combined cadmium in QD Vision TVs and the power plant emissions associated with their use is actually lower than that associated with conventional flat screen TVs. In other words, using cadmium in quantum dots for production of more energy-efficient displays can actually results in a net reduction in cadmium emissions.

Not the conclusion one might have drawn at the outset, eh? You can read the essay in its entirety on either Nanowerk (Jan. 8, 2015 essay) or The Conversation (Jan. 7, 2015 essay). (Same essay just different publication dates.) Andrew has also posted his essay on the University of Michigan Risk Science Center website, Are quantum dot TVs – and their toxic ingredients – actually better for the environment? Note: Andrew Maynard is the center’s director.

Patenting a new method for controlling the size and composition of nanoparticles

A research team at the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan has developed and patented a new more precise production technique for nanoparticles, specifically quantum dots. From a Jan. 5, 2014 news item on Nanowerk, (Note:  A link has been removed),

The Nanoparticles by Design Unit at the Okinawa Institute of Science and Technology Graduate University is constantly finding new ways to endow the tiniest of particles with more specific properties. They have developed methods to control the size and chemical composition of nanoparticles, and now they have found a way to control the degree of crystallinity, or the way that atoms align inside the nanoparticles. A nanoparticle’s crystallinity impacts its optical, magnetic, and electrical properties. Professor Mukhles Sowwan and the researchers in his unit Dr. Cathal Cassidy and Vidyadhar Singh have applied for a patent for their method, which describes exactly how to create semiconductor nanoparticles of varying crystallinity.

A Jan. 5, 2015 OIST news release, which originated the news item,  describes the researchers’ work in more detail,

“Most scientists and even companies nowadays are using nanoparticles not optimized for their applications or devices,” explains Sowwan. “We hope, at a certain time, we will optimize the nanoparticles for specific applications.” To start though, the researchers in the Nanoparticles by Design Unit must figure out how to control a few basic characteristics of nanoparticles, such as crystallinity. A crystalline nanoparticle will have all of its atoms aligned in neat rows, while an amorphous nanoparticle will have more disordered atoms. A polycrystalline structure has atoms aligned in groups, which are also known as grains. Crystallinity is responsible for profound differences between products made of the same material. For example, soot is amorphous carbon, or carbon without any crystal grains, while diamonds are crystalline carbon.

“It’s the first time to control the crystallinity and the number of crystallites of very small semiconductor nanoparticle,” Sowwan says, explaining that people have long known how to induce crystallinity in bulk semiconductor materials. But part of the reason why Sowwan can control certain characteristics is because of the experimental method he and his researchers use, based on a modified nanoparticle deposition system. One of the most important features of this system is the possibility to interact with or modify freshly formed semiconductor nanoparticles in flight before reaching a substrate. “That substrate is problematic,” explains Sowwan, “because it is always impacting the properties of the nanoparticle.” Following the steps described in the newly suggested method, nanoscientists expose these nanoparticles in flight to a beam of metal atoms. The metal atoms diffuse onto the surface of the nanoparticles and form metal nanoclusters, just a few nanometers wide, inducing crystallization in the product. The researchers can then selectively remove the metal nanoclusters with plasma cleaning, a fairly simple physical procedure, retaining only the intact semiconductor nanoparticles of desired crystallinity.

The new patent will credit this method to OIST.  “To use this method for commercial purposes, such as engineered nanoparticles in solar cells or for medical bio-imaging, the technology will have to be licensed from OIST,and academic researchers will have to credit us in their research.” Sowwan says this is one of many characteristics he would like to control in order to produce more specialized nanoparticles. At the end of the day, this is one new set of directions in the rulebook of how to customize a nanoparticle.

It’s not clear how much money, if any,  OIST will be charging should other researchers choose to avail themselves of this technology. At present, you can take a look at the patent application which makes for some very interesting reading,

Patent application number: WO 2014141662 A1, Metal Induced Crystallization of Semiconductor Quantum Dots via google

The present invention relates to metal induced crystallization of amorphous semiconductor, and in particular, to metal induced crystallization of amorphous semiconductor small dots and quantum dots.

Control of crystallinity and grain structure has been a central component of advanced materials engineering and metallurgy for centuries, ranging from forging of ancient Japanese katana or swords (Non-Patent Literature No. 1) to modern nano-engineered transistor gate electrodes (Non-patent Literature Nos. 2 and 3). …

My understanding is that this is a US patent.

Self-healing (high voltage installations) in the subsea and a search for funding

More concept than reality, nonetheless, the possibilities offered by this Scandinavian research are appealing. From a Dec. 16, 2014 news item on ScienceDaily,

Embryonic faults in subsea high voltage installations are difficult to detect and very expensive to repair. Researchers believe that self-repairing materials could be the answer.

The vital insulating material which encloses sensitive high voltage equipment may now be getting some ‘first aid’.

“We have preliminary results indicating that this is a promising concept, but we need to do more research to check out other solutions and try the technique out under different conditions.” So says SINTEF [largest independent research organisation in Scandinavial researcher Cédric Lesaint, who is hoping that the industry will soon wake up to the idea.

A Nov. 26, 2014 SINTEF press release, which originated the news item, describes the concept in more detail,

The technology used involves so-called ‘microcapsules’, which are added to traditional insulation materials and have the ability to ‘sniff out’ material fatigue and then release repairing molecules. The team working on this project is made up of chemists, physicists and electrical engineers. If they succeed, they may have discovered the next generation of insulating materials which can be applied in costly electrical installations.

The press release then describes a phenomenon named ‘electrical trees’,

So-called electrical trees develop in electrical insulation materials that are approaching the end of their useful lives. Electrical stress fields exploit small weaknesses in the insulation material and generate hair-thin channels that spread through the material like the branches of a tree. When the channels finally reach the surface of the insulation material, the damage is done and short-circuiting will occur.

“Short-circuiting is almost always linked to an electrical tree”, explains Lesaint’s colleague, Øystein Hestad.

Faults of this kind are extremely expensive to repair, especially if they occur in a device installed on an offshore wind farm or a subsea oil production installation – perhaps even under inhospitable Arctic conditions.

Under such conditions, say researchers, self-repairing insulation materials represent a cost-effective alternative to traditional repair methods.

The specific solution the researchers propose (from the press release),

SINTEF researchers have based their work on an established idea developed to repair mechanical damage and cracks in composite materials. The composites are mixed with microcapsules filled with a liquid monomer – single molecules which have the property to join with each other (polymerise) to form long-chain molecules. If cracks or other forms of damage encroach on the capsules, the monomer is released and fills the cracks.

“As far as we know, we’re the first to have tested this technique on damage resulting from electrical stress fields”, says Lesaint.

The microcapsules they incorporated into the insulation materials burst when they encounter one of the branches of an electrical tree. The liquid monomer then invades the thin channels forming the ‘tree’ and polymerises. The channels are filled in and the electrical degradation of the insulation material is halted.

In this way the ‘immune defences’ of the insulation material are strengthened, and the lifetime of the installation extended.

As promising as the research is, the scientists are looking for funds (from the press release),

This summer [2014], the SINTEF research team presented the concept at a conference in Philadelphia, USA.

“Many people were surprised, especially when they realised that we had chosen to share the concept with others”, says Lesaint. “Taking the chance that other researchers might steal such a good idea is a risk we have to take”, he says.

The industry has also expressed some interest, but so far not enough to consider funding further research.

“We’re being met with curious interest, but have been told to come back when we have more test results”, says Lesaint. “The problem is that at present we have insufficient funds to conduct the research needed to carry the project forward”, he says.

Next year [2015?] will thus decide as to whether this self-repairing project will take the step from being a promising concept to becoming the next generation of insulation materials.

You can also find the press release/article by Lars Martin Hjortho here in  a Gemini.no newsletter.

Here’s an illustration the researchers have made available,

Subsea installations can get longer life-time with self-repairing materials. Illustration: SINTEF Energy  [downloaded from http://gemini.no/en/2014/11/self-repairing-subsea-material/]

Subsea installations can get longer life-time with self-repairing materials. Illustration: SINTEF Energy [downloaded from http://gemini.no/en/2014/11/self-repairing-subsea-material/]

Projecting beams of light from contact lenses courtesy of Princeton University (US)

Princeton University’s 3D printed contact lenses with LED (light-emitting diodes) included are not meant for use by humans or other living beings but they are a flashy demonstration. From a Dec. 10, 2014 news item on phys.org,

As part of a project demonstrating new 3-D printing techniques, Princeton researchers have embedded tiny light-emitting diodes into a standard contact lens, allowing the device to project beams of colored light.

Michael McAlpine, the lead researcher, cautioned that the lens is not designed for actual use—for one, it requires an external power supply. Instead, he said the team created the device to demonstrate the ability to “3-D print” electronics into complex shapes and materials.

“This shows that we can use 3-D printing to create complex electronics including semiconductors,” said McAlpine, an assistant professor of mechanical and aerospace engineering. “We were able to 3-D print an entire device, in this case an LED.”

A Dec. 9, 2014 Princeton University news release by John Sullivan, which originated the news item, describes the 3D lens, the objectives for this project, and an earlier project involving a ‘bionic ear’ in more detail (Note: Links have been removed),

The hard contact lens is made of plastic. The researchers used tiny crystals, called quantum dots, to create the LEDs that generated the colored light. Different size dots can be used to generate various colors.

“We used the quantum dots [also known as nanoparticles] as an ink,” McAlpine said. “We were able to generate two different colors, orange and green.”

The contact lens is also part of an ongoing effort to use 3-D printing to assemble diverse, and often hard-to-combine, materials into functioning devices. In the recent past, a team of Princeton professors including McAlpine created a bionic ear out of living cells with an embedded antenna that could receive radio signals.

Yong Lin Kong, a researcher on both projects, said the bionic ear presented a different type of challenge.

“The main focus of the bionic ear project was to demonstrate the merger of electronics and biological materials,” said Kong, a graduate student in mechanical and aerospace engineering.

Kong, the lead author of the Oct. 31 [2014] article describing the current work in the journal Nano Letters, said that the contact lens project, on the other hand, involved the printing of active electronics using diverse materials. The materials were often mechanically, chemically or thermally incompatible — for example, using heat to shape one material could inadvertently destroy another material in close proximity. The team had to find ways to handle these incompatibilities and also had to develop new methods to print electronics, rather than use the techniques commonly used in the electronics industry.

“For example, it is not trivial to pattern a thin and uniform coating of nanoparticles and polymers without the involvement of conventional microfabrication techniques, yet the thickness and uniformity of the printed films are two of the critical parameters that determine the performance and yield of the printed active device,” Kong said.

To solve these interdisciplinary challenges, the researchers collaborated with Ian Tamargo, who graduated this year with a bachelor’s degree in chemistry; Hyoungsoo Kim, a postdoctoral research associate and fluid dynamics expert in the mechanical and aerospace engineering department; and Barry Rand, an assistant professor of electrical engineering and the Andlinger Center for Energy and the Environment.

McAlpine said that one of 3-D printing’s greatest strengths is its ability to create electronics in complex forms. Unlike traditional electronics manufacturing, which builds circuits in flat assemblies and then stacks them into three dimensions, 3-D printers can create vertical structures as easily as horizontal ones.

“In this case, we had a cube of LEDs,” he said. “Some of the wiring was vertical and some was horizontal.”

To conduct the research, the team built a new type of 3-D printer that McAlpine described as “somewhere between off-the-shelf and really fancy.” Dan Steingart, an assistant professor of mechanical and aerospace engineering and the Andlinger Center, helped design and build the new printer, which McAlpine estimated cost in the neighborhood of $20,000.

McAlpine said that he does not envision 3-D printing replacing traditional manufacturing in electronics any time soon; instead, they are complementary technologies with very different strengths. Traditional manufacturing, which uses lithography to create electronic components, is a fast and efficient way to make multiple copies with a very high reliability. Manufacturers are using 3-D printing, which is slow but easy to change and customize, to create molds and patterns for rapid prototyping.

Prime uses for 3-D printing are situations that demand flexibility and that need to be tailored to a specific use. For example, conventional manufacturing techniques are not practical for medical devices that need to be fit to a patient’s particular shape or devices that require the blending of unusual materials in customized ways.

“Trying to print a cellphone is probably not the way to go,” McAlpine said. “It is customization that gives the power to 3-D printing.”

In this case, the researchers were able to custom 3-D print electronics on a contact lens by first scanning the lens, and feeding the geometric information back into the printer. This allowed for conformal 3-D printing of an LED on the contact lens.

Here’s what the contact lens looks like,

Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton, is leading a research team that uses 3-D printing to create complex electronics devices such as this light-emitting diode printed in a plastic contact lens. (Photos by Frank Wojciechowski)

Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton, is leading a research team that uses 3-D printing to create complex electronics devices such as this light-emitting diode printed in a plastic contact lens. (Photos by Frank Wojciechowski)

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

3D Printed Quantum Dot Light-Emitting Diodes by Yong Lin Kong, Ian A. Tamargo, Hyoungsoo Kim, Blake N. Johnson, Maneesh K. Gupta, Tae-Wook Koh, Huai-An Chin, Daniel A. Steingart, Barry P. Rand, and Michael C. McAlpine. Nano Lett., 2014, 14 (12), pp 7017–7023 DOI: 10.1021/nl5033292 Publication Date (Web): October 31, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

I’m always a day behind for Dexter Johnson’s postings on the Nanoclast blog (located on the IEEE [institute of Electrical and Electronics Engineers]) so I didn’t see his Dec. 11, 2014 post about these 3Dprinted LED[embedded contact lenses until this morning (Dec. 12, 2014). In any event, I’m excerpting his very nice description of quantum dots,

The LED was made out of the somewhat exotic nanoparticles known as quantum dots. Quantum dots are a nanocrystal that have been fashioned out of semiconductor materials and possess distinct optoelectronic properties, most notably fluorescence, which makes them applicable in this case for the LEDs of the contact lens.

“We used the quantum dots [also known as nanoparticles] as an ink,” McAlpine said. “We were able to generate two different colors, orange and green.”

I encourage you to read Dexter’s post as he provides additional insights based on his long-standing membership within the nanotechnology community.

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.