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Graphene has put its foot in the door towards real-world electronics

Original news release was issued by the Iowa State University.
Graphene is essentially a wonderkid material, as we have reported time and time again. It’s great at conducting heat and electricity, and it’s extremely strong and stable, on top of being only an atom thick. These amazing properties would single-handedly transform the world of consumer electronics, not to mention industrial applications. But researchers have struggled to move beyond tiny lab samples for studying its material properties to larger pieces for real-world applications.
Recent projects that used inkjet printers to print multi-layer graphene circuits and electrodes had the engineers thinking about using it for flexible, wearable and low-cost electronics. For example, “Could we make graphene at scales large enough for glucose sensors?” asked Suprem Das, an Iowa State postdoctoral research associate in mechanical engineering and an associate of the U.S. Department of Energy’s Ames Laboratory.

“The breakthrough of this project is transforming the inkjet-printed graphene into a conductive material capable of being used in new applications,” Claussen said.

But there were problems with the existing technology. Once printed, the graphene had to be treated to improve electrical conductivity and device performance. That usually meant high temperatures or chemicals — both could degrade flexible or disposable printing surfaces such as plastic films or even paper.
Das and Claussen came up with the idea of using lasers to treat the graphene. Claussen, an Iowa State assistant professor of mechanical engineering and an Ames Laboratory associate, worked with Gary Cheng, an associate professor at Purdue University’s School of Industrial Engineering, to develop and test the idea.

Suprem Das holds graphene electronics printed on a sheet of paper. Das and Jonathan Claussen, right, are using lasers to treat the printed graphene electronics. The process improves conductivity and enables flexible, wearable and low-cost electronics. (Photo by Christopher Gannon)
Suprem Das holds graphene electronics printed on a sheet of paper. Das and Jonathan Claussen, right, are using lasers to treat the printed graphene electronics. The process improves conductivity and enables flexible, wearable and low-cost electronics. (Photo by Christopher Gannon)

And it worked: They found treating inkjet-printed, multi-layer graphene electric circuits and electrodes with a pulsed-laser process improves electrical conductivity without damaging paper, polymers or other fragile printing surfaces.
“This creates a way to commercialize and scale-up the manufacturing of graphene,” Claussen said.
Its applications could include sensors with biological applications, energy storage systems, electrical conducting components and even paper-based electronics.
To make all that possible, the engineers developed computer-controlled laser technology that selectively irradiates inkjet-printed graphene oxide. The treatment removes ink binders and reduces graphene oxide to graphene — physically stitching together millions of tiny graphene flakes. The process makes electrical conductivity more than a thousand times better.
That localized, laser processing also changes the shape and structure of the printed graphene from a flat surface to one with raised, 3-D nanostructures. The engineers say the 3-D structures are like tiny petals rising from the surface. The rough and ridged structure increases the electrochemical reactivity of the graphene, making it useful for chemical and biological sensors.
All of that, according to Claussen’s team of nanoengineers, could move graphene to commercial applications.
“This work paves the way for not only paper-based electronics with graphene circuits,” the researchers wrote in their paper, “it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells and (medical) devices.”

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Carbon nanotubes are about to dethrone silicon chips and reinstate Moore's law

Original news release was issued by American Technion Society, written by Kevin Hattori.

The next step in electronic design is clear as day. With silicon chips reaching their limit, development of carbon nanotubes may be about to usher us in the age of molecular electronics.

Our electronics, powered by silicon chips, are quickly reaching their limit, as chips smaller than 5nm will simply overheat. That raises question marks around Moore’s law, which has, since its formulation in 1965, become a tent pole that guides the market of digital electronics. Many researchers are hard at work to develop an alternative to silicon and it has been pretty clear for a while that carbon nanotubes (CNTs) will be the way to go because of their unprecedented electrical, optical, thermal and mechanical properties.
But due to the nanometer size of the CNTs (100,000 times smaller in diameter than the thickness of a human hair) it is very tricky to build uniform CNTs on a large scale. As stated by the leader of the research team, Prof. Yuval Yaish of the Viterbi Faculty of Electrical Engineering, “Current methods for the production of CNTs are slow, costly, and imprecise. As such, they generally cannot be implemented in industry.” Better methods for CNT growing are necessary before we can take the leap in computing, which is precisely what Yaish and his team have done.

Screen-Shot-2016-07-11-at-3.37.39-PM
Preferential adsorption of p-nitrobenzoic acid on carbon nanotubes. (a) Top: Chemical structure of p-nitrobenzoic acid (pNBA). Bottom: Schematic illustration of the monoclinic unit cell of pNBA powder as extracted from X-ray diffraction analysis. (b,c) Dark field optical microscopy images of pNBA nanocrystals adsorbed along CVD grown carbon nanotubes (CNTs). Scale bar, 50 and 20 µm, respectively. (d) Amplitude image of AFM of a single CNT with a few pNBA nanocrystals along. Scale bar, 1 µm. Inset: height cross sections along the marked lines of the main figure. (e) Dark field optical microscopy image of pNBA nanocrystals after intensive deposition. Note the black voids along the CNT. Scale bar, 20 µm. (f) Dark field optical microscopy image of pNBA nanocrystals adsorb onto commercial dispersed CNTs. Scale bar, 20 µm. (Source: ATS)

They have developed a simple, rapid, non-invasive and scalable technique that enables optical imaging of CNTs. Instead of depending upon the CNT chemical properties to bind marker molecules, the researchers relied on the fact that the CNT is both a chemical and physical defect on the otherwise flat and uniform surface. It can serve as a seed for the nucleation and growth of small, but optically visible nanocrystals, which can be seen and studied using a conventional optical microscope. Since the CNT surface is not used to bind the molecules, they can be removed completely after imaging, leaving the surface intact, and preserving the CNT’s electrical and mechanical properties.
“Our approach is the opposite of the norm,” Yaish continued. “We grow the CNTs directly, and with the aid of the organic crystals that coat them, we can see them under a microscope very quickly. Then image identification software finds and produces the device (transistor). This is the strategy. The goal is to integrate CNTs in an integrated circuit of miniaturized electronic components (mainly transistors) on a single chip (VLSI). These could one day serve as a replacement for silicon electronics.”

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Nanoparticles close in on cardiovascular diseases in a non-surgical strike

Via ScienceNews MagazineVol. 189, No. 12, June 11, 2016, p. 22, original article written by Sarah C. P. Williams
Cardiovascular diseases are still one of the deadliest killers in the world, with statistics even worse than cancer. In countries like the US, where more than 10 percent of the population has been diagnosed with a heart disease, it is a serious cause for concern. And while current treatment really only brings short-term effects, the new emerging area of nanomedicine is looking to get right down to the cause. The proposition is simple – to destroy waxy plaques in blood vessels with targeted nanomissiles.
Nanoparticles are tiny in comparison to red cells in our bloodstream, but they have already made a huge difference under experimental conditions. They are designed to carry molecules that break down clots and clean arteries, enabling natural free flow in the bloodstream. This approach of active substance being carried on a nanoparticle is already used in cancer treatment, but works on systems agaist cardiovascular disease have only just started. “Some nanoparticles home in on the plaques by binding to immune cells in the area, some do so by mimicking natural cholesterol molecules and others search for collagen exposed in damaged vessel walls. Once at the location of a plaque, either the nanoparticles themselves or a piggybacked drug can do the cleanup work”, reports ScienceNews.

Sources: ScienceNews/Nicolle Rager Fuller/M.E. Lobatto et al/Nat. Rev. Drug Discov. 2011; N. Korin et al/Science 2012

We are still ways off picking up preventative cardiovascular nanomedicine from our local pharmacies, but mice have shown significant results in the first reported tests, reaching the blockage decrease of 37%.
Furthermore, one of the plaque-targeting nanoparticles that is now used to treat rheumatoid arthritis has severe side effects such as vomiting and hair loss. Being able to target this substance to a specific area in the body would enable the use of lower volume at the same effectiveness. With side effects diminished, this drug could be comfortably used by more people than just those who need it desperately.
But before we all get really excited, we should remind ourselves that cardiovascular nanoparticles have only been tested on animals thus far, and although no signs of toxicity have been found, it remains a concern for such a novel drug. “I really don’t foresee that you would start preventively treating patients who don’t have symptoms with nanoparticles,” says Willem Mulder, a nanomedicine researcher at the University of Amsterdam and the Icahn School of Medicine at Mount Sinai in New York City. “But to take a person who’s hospitalized after a heart attack and stick a needle in their arm and infuse nanoparticles, that’s not hard.”
 

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DNA assembly is approaching 3D-printing levels of convenience

Original news release was published by MIT, written by Helen Knight.

Researchers can build complex, nanometer-scale structures of almost any shape and form, using strands of DNA. But these particles must be designed by hand, in a complex and laborious process. This has limited the technique, known as DNA origami, to just a small group of experts in the field.

Now a team of researchers at MIT and elsewhere has developed an algorithm that can build these DNA nanoparticles automatically.

In this way the algorithm, which is reported together with a novel synthesis approach in the journal Science this week, could allow the technique to be used to develop nanoparticles for a much broader range of applications, including scaffolds for vaccines, carriers for gene editing tools, and in archival memory storage.

Unlike traditional DNA origami, in which the structure is built up manually by hand, the algorithm starts with a simple, 3-D geometric representation of the final shape of the object. It then decides how it should be assembled from DNA, according to Mark Bathe, an associate professor of biological engineering at MIT, who led the research.

“The paper turns the problem around from one in which an expert designs the DNA needed to synthesize the object, to one in which the object itself is the starting point, with the DNA sequences that are needed automatically defined by the algorithm,” Bathe says.

“Our hope is that this automation significantly broadens participation of others in the use of this powerful molecular design paradigm.”

The algorithm first represents the object as a perfectly smooth, continuous outline of its surface. It then breaks the surface up into a series of polygonal shapes. Next, it routes a long, single strand of DNA, called the scaffold, which acts like a piece of thread, throughout the entire structure to hold it together. The algorithm weaves the scaffold in one fast and efficient step, which can be used for any shape of 3-D object, Bathe says.

The algorithm, which is known as DAEDALUS (DNA Origami Sequence Design Algorithm for User-defined Structures), can build any type of 3-D shape, provided it has a closed surface.

The researchers are now investigating a number of applications for the DNA nanoparticles built by the DAEDALUS algorithm. One such application is a scaffold for viral peptides and proteins for use as vaccines.

The researchers demonstrated that the DNA nanoparticles are stable for more than six hours in serum, and are now attempting to increase their stability further. The team is also investigating the use of the nanoparticles as DNA memory blocks. Previous research has shown that information can be stored in DNA, in a similar way to the 0s and 1s used to store data digitally. The information to be stored is “written” using DNA synthesis and can then be read back using DNA sequencing technology.

The most exciting aspect of the work, however, is that it should significantly broaden participation in the application of this technology, Bathe says, much like 3-D printing has done for complex 3-D geometric models at the macroscopic scale.

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Combining water-repellence methods makes water bounce off surface

An anomalous phenomenon was observed by Doo Jin Lee and Young Seok Song from Department of Materials Science and Engineering of Seoul National University in South Korea. This anomaly was observed when two methods of water repellence were combined. Leidenfrost effect in combination with Cassie state made the water droplets bounce on the surface. And while sliding on the surface, or even levitating above it is ‘normal’, this bouncy anomaly may have impending implications for the future water repelling materials.

Leidenfrost effect is something we observe in the kitchen every now and then. When a surface is heated above Leidenfrost temperature (varying for different liquids of course) it won’t get wet, because the liquid will boil upon coming to contact with the surface, creating a vapor on which the liquid can then levitate. The German scientist discovered this back in 1756.

Cassie state on the other hand, relies on textured surfaces. If these are structured in a way that leaves enough space for air, the water will be supported by its high surface tension. In other words, if the surface is rough enough, the water will not get it wet. This hydrophobic property is characteristic of lotus plants. This property is copied on man made materials and widely used in various designs and installations.

In their study, the Lee and Song tested Leidenfrost effect on nanostructured Cassie surface and on a classic hydrophobic surface (achieved by fluorination). The results from the two surfaces varied significantly. The experiment was a lot more successful on the Cassie nanostructure than on its classic counterpart. The said bouncing only occurred on the nanosurface. “Our future work will focus on developing multiscale structures with microscale and nanoscale regularities, and explore the nonwetting characteristics of their surfaces with the dynamic Leidenfrost effect,” noted Doo Jin Lee in an interview.

Research in this area could be used to produce better materials for windows, paint, coating and windshields. This high water-repellent materials could save time cleaning windows, but also lives lost in traffic accidents during rainy days. The potential of these materials is immense and that is why more and more research is conducted in this area.

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The world's tiniest engine could power tomorrow's nanomachines

Original press release was issued by the University of Cambridge.

Nanomachines have long been the dream of many scientists and science-fiction fans alike. However, with the latest research into nano-scale engines from the University Cambridge, we may finally be on the cusp of real life, fully functional nano-bots that appear to be extraordinarily efficient and scalable.

What researchers have developed is essentially the world’s tiniest engine that is just a billionth of a metre small, and uses light to power itself. The technology used would allow it to power nanomachines capable of navigating in the water, sense the environment around them, or enter living cells to fight disease.

“We know that light can heat up water to power steam engines,” said study co-author Dr Ventsislav Valev. “But now we can use light to power a piston engine at the nanoscale.”

The prototype device is made of tiny charged particles of gold, bound together with temperature-responsive polymers in the form of a gel. When the ‘nano-engine’ is heated to a certain temperature with a laser, it stores large amounts of elastic energy in a fraction of a second, as the polymer coatings expel all the water from the gel and collapse. This has the effect of forcing the gold nanoparticles to bind together into tight clusters. But when the device is cooled, the polymers take on water and expand, and the gold nanoparticles are strongly and quickly pushed apart, like a spring.

“It’s like an explosion,” said Dr Tao Ding from Cambridge’s Cavendish Laboratory, and the paper’s first author. “We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them.”

The prototype isn’t just functional – it is efficient. Its ratio of force per unit weight exceeds those of all previously produced devices, including ordinary engines and muscles. On top of that, it is reported to be bio-compatible, cost-effective to manufacture, fast to respond, and energy efficient.

Professor Jeremy Baumberg from the Cavendish Laboratory, who led the research, has named the devices ‘ANTs’, or actuating nano-transducers. “Like real ants, they produce large forces for their weight. The challenge we now face is how to control that force for nano-machinery applications.”

The research suggests how to turn Van de Waals energy – the attraction between atoms and molecules – into elastic energy of polymers and release it very quickly. “The whole process is like a nano-spring,” said Baumberg. “The smart part here is we make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible.”

The team is currently working with Cambridge Enterprise, the University’s commercialisation arm, and several other companies with the aim of commercialising this technology for microfluidics bio-applications.

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After 200 thousand recharges, California-made battery lives on

Original news release was published by University of California.

Another daily struggle of smart-device users might have been solved in Irvine, California. Nearly all the devices we use on daily basis have one vital flaw. The battery. No matter the manufacturer, no matter the miliampere-hours, batteries significantly lose their capacity to carry electricity after a certain number of recharges. In consumer tech, this number is in hundreds, in advanced and specialized batteries it spans in thousands. With usage of nanorods (wires with diameter thousands times thinner than human hair) and graphene, they were able to get around 10 thousand recharges before significant battery fade.

battery
Scheme portraying the effect of PMMA gel. A – before B – after; Image courtesy of ACS Energy Letters

The problem with nanorods was, that because of their size, they are very fragile. In a typical lithium-ion battery, they quickly crack and the recharging cycle gets damaged. So far, the problem tackled by placing them into a liquid electrolyte, which led to a very long lifetime. Several thousand recharges were easily achievable, with only variable being the materials used.

UCI researchers tried an innovative approach, and instead of focusing on different liquids, they used a Plexiglas-like gel electrolyte. Golden nano-wires, each 5 milimeters in total length, were first coated in manganese dioxide and then covered with poly(methyl methacrylate) (PMMA) gel electrolyte. It took Mya Le Thai, the leader of this study and a doctoral candidate at UCI, eleven weeks to get the battery capacity to 94-96% of the original charge. It amounts to 200 thousand cycles of discharging and recharging.

“Mya was playing around, and she coated this whole thing with a very thin gel layer and started to cycle it,” said Reginald Penner, chair of UCI’s chemistry department. “She discovered that just by using this gel, she could cycle it hundreds of thousands of times without losing any capacity.”

Hard work and creativity of the scientists in California has paid off. Lifespans of consumer-used batteries could be greatly improved thanks to this discovery. Successfully implementing this technology on market would bring more consumer satisfaction, less energy consumption, and lesser amount of toxic waste – a topic tightly connected to disposal of old batteries. Hopefully, PMMA-electrolyte battery will make a smooth transition to consumer tech.

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Tesla coil causes these nanotubes to self-assemble into circuits

The original news released was published by the Rice University News & Media department, written by Mike Williams.

Although visually impressive, the inventions of Nikola Tesla haven’t been used for much aside from entertainment and education for the better part of the last century. This may be about to change, as scientists at Rice University have discovered that the strong force field emitted by a Tesla coil causes carbon nanotubes to self-assemble into long wires, a phenomenon they call “Teslaphoresis.” Paul Cherukuri, the lead researcher, sees these findings as a clear path towards scalable assembly of nanotubes.

The system works by remotely oscillating positive and negative charges in each nanotube, causing them to chain together into long wires. We recommend looking at the Rice University News video below to see the self-assembly in action.

Tesla coil causes nanotubes to do more than just self-assemble. As demonstrated in the video, nanotubes have formed a kind of circuit that connected two LED lights, and powered them by absorbing electric energy from the coil’s field. Additionally, it moved the assembled nanotubes towards the coil from across the room in a tractor beam-like effect.

“Electric fields have been used to move small objects, but only over ultrashort distances,” Cherukuri said. “With Teslaphoresis, we have the ability to massively scale up force fields to move matter remotely.”

It has been suggested that by using Tesla coils of various sizes and in different numbers, it should be possible to form more intricate self-assembling nanostructures. Entire electrical grids would be the obvious first choice, but as Lindsey Bornhoeft, the paper’s lead author, suggested, its uses are potentially huge: “These nanotube wires grow and act like nerves, and controlled assembly of nanomaterials from the bottom up may be used as a template for applications in regenerative medicine.”

“There are so many applications where one could utilize strong force fields to control the behavior of matter in both biological and artificial systems,” Cherukuri said. “And even more exciting is how much fundamental physics and chemistry we are discovering as we move along. This really is just the first act in an amazing story.”

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Self-assembling bio-inspired nanotubes discovered

Original news release was first published at EurekAlert.

We still have ways to go when it comes to reliable nanotechnology. It is already being used in modern computer parts and variety of consumer electronics, as well as water-resistant fabrics. However, consistent production of more sophisticated nanostructures is still proving extremely difficult. Nanotubes with diameter of a few bilionths of a meter would enable advanced applications, such as injecting cancer-fighting drugs directly into cells, or removing salt from seawater, but some serious precision is required for mass production of such miniscule structures.

Progress has been made, though. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have discovered a family of polymers that spontaneously assemble into hollow crystalline nanotubes upon being placed in water. These tubes can even be adjusted to a diameter between 5 and 10 nanometers, depending on the length of the polymer chain. They are made out of two chemically disctinct bars which form a molecular tile ring, bundling up into nanotubes up to 100 nanometers long.

“This points to a new way we can use synthetic polymers to create complex nanostructures in a very precise way,” says Ron Zuckermann, who directs the Biological Nanostructures Facility in Berkeley Lab’s Molecular Foundry, where much of this research was conducted.

Zuckermann has also suggested that the adjustable diameter of the tubes could theoratically allow for advanced filtration and desalination technologies. It is the kind of functionality that resembles proteins found in nature, but made out of durable materials. There is still research to be done to determine how exactly these tubes are formed, but Berkeley Lab’s findings have cleared up a lot of questions regarding their structure. This information could reveal new design principles, helping us put together complex nanostructures in the future.

What makes these nanotubes stand out, is that they are created without the approaches traditionally used in nanotechnology, mainly electrostatic interactions or hydrogen bond networks. Zuckerman added: “You wouldn’t expect something as intricate as this could be created without these crutches, but it turns out the chemical interactions that hold these nanotubes together are very simple. What’s special here is that the two peptoid blocks are chemically distinct, yet almost exactly the same size, which allows the chains to pack together in a very regular way. These insights could help us design useful nanotubes and other structures that are rugged and tunable – and which have uniform structures.”