Tag Archives: carbon nanotubes

Carbon Yarn.

Researchers design carbon yarn that generates energy from motion or waste heat

An international research effort has produced high-tech yarns that pump out electricity when stretched or twisted.

Carbon Yarn.

Image credits Shi Hyeong Kim et al., 2017.

The “Twistron” yarns are the product of a research team led by scientists from the University of Texas at Dallas and Hanyang University in South Korea. Due to the high rate with which the twistrons transform motion into electricity, they could be used to tap into ambiental energy sources. Ocean waves, waste heat, even our breathing motions could be harvested for usable power.

Twist and turn on

“The easiest way to think of twistron harvesters is, you have a piece of yarn, you stretch it, and out comes electricity,” said Dr. Carter Haines, co-lead author of the paper and an associate research professor in the Alan G. MacDiarmid NanoTech Institute at UT Dallas.

The yarns are built from carbon nanotubes, hollow carbon cylinders which are about 10,000 times thinner than a strand of human hair. The team spun these into high-strength yarns, then twisted them until they coiled to make them elastic. The last step was to coat the strands with an electrolyte (an ionically conductive material), which can be something as mundane as a water and salt solution. The end result, the twistron, acts much like a supercapacitor. A capacitor is a device used to store electrical charges, and they usually require an external source of current such as a battery. But these yarns are capacitors capable of generating their own charge.

The fundamental working principle is that when the nanotube yarns get pushed into the electrolyte, they become electrically charged. Because of the twist imparted onto the strand, whenever the Twistron is twisted or stretched its volume decreases, bringing the electric charges on the yarn closer together and increasing the overall energy of the strand, Haines said. This increase translates into a higher voltage across the yarn. In essence, mechanical motions in our scale of reference lead to changes on a very small scale that produce energy we can harvest.

According to the study’s corresponding author, Dr. Ray Baughman, director of the NanoTech Institute, 30 stretches a second generated 250 watts per kilogram of peak electrical power normalized to the harvester’s weight (i.e. this is a calculated value). Which is actually quite a lot of energy from simple motion.

“Although numerous alternative harvesters have been investigated for many decades, no other reported harvester provides such high electrical power or energy output per cycle as ours for stretching rates between a few cycles per second and 600 cycles per second,” he explains.

Experimentally, a twistron yarn weighing a few milligrams (for comparison, a typical male housefly weighs around 11,5 mg) could light up a small LED on every stretch. When sewed into a shirt, the yarn generated an electrical signal on each breath, showcasing its potential as a self-powered breathing biomonitor. To make it able to tap into wasted thermal energy, the team connected the Twistron to an artificial polymer muscle which contracts and expands with temperature.

All of this could mean that Twistron technology is ideally-suited to power wearable electronics and supply energy for really small devices where batteries would simply be impractical.

“There is a lot of interest in using waste energy to power the Internet of Things, such as arrays of distributed sensors,” said Dr. Na Li, a research scientist at the NanoTech Institute and co-lead author of the study.

Bigger fish to fry

It’s not all about the very small, however. The team also wanted to show that their strands can be used to tap into currently under-exploited forms of power, such as sea waves. As a proof-of-concept demonstration of both this and the strands’ ability to work in more chemically-complex environments, such as ocean water, the team deployed a Twistron on the east coast of South Korea. A 1-milligram, 10 centimeter-(4 inch-) long strand was tied to a balloon on one end and a weight that rested on the seabed. With every wave, the balloon would rise and stretch the yarn by up to 25%, generating electricity.

Although it only produced very small amounts of power in this attempt, the team showed that the technology’s output is scalable either by increasing diameter or by employing bundles of the strands in parallel. The only barrier to their mastery of wave-energy is cost, as building enough strands for this application would be quite pricey. However, for applications requiring relatively low levels of power, such as sensors or sensor communications, you only need small twistrons — which don’t cost very much. The team reports that “just 31 milligrams of carbon nanotube yarn harvester could provide the electrical energy needed to transmit a 2-kilobyte packet of data over a 100-meter radius every 10 seconds for the Internet of Things.”

The paper “Harvesting electrical energy from carbon nanotube yarn twist” has been published in the journal Science.

Inside carbon nanotubes, MIT researchers found water solidifies at temperatures that would normally see it boiling. Credit: MIT

Water trapped in carbon nanotubes starts freezing at the temperature it should be boiling

Inside carbon nanotubes, MIT researchers found water solidifies at temperatures that would normally see it boiling. Credit: MIT

Inside carbon nanotubes, MIT researchers found water solidifies at temperatures that would normally see it boiling. Credit: MIT

Phase change — the transition substances make from solid, liquid, gas — is a lot more dynamic than most people think. At sea-level, water starts boiling at around 100 degrees Celsius and freezes at zero C. If you confine the same volume of water in a small space, thus exerting pressure, you’ll need more energy to boil water. This is common knowledge but few thought you could drastically alter normal boiling point conditions by trapping water in small cavities. MIT did this recently with carbon nanotubes and found water started freezing at 100 C.

The weirdest ice

Carbon nanotubes are among the thinnest materials we know. Inside them, you can’t cram something thicker than a couple of water molecules. “If you confine a fluid to a nanocavity, you can actually distort its phase behavior,” Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. That’s to say everyone expected phase change conditions to be altered but the magnitude blew everyone away.

Experiments suggest the water inside the carbon nanotubes solidified at 105 degrees Celsius. At this scale, well below the billionth of a meter, reading temperature can prove challenging. It’s possible that the actual freezing temperature is in excess of 150 degrees Celsius, the MIT researchers note in their paper.

Nevertheless, the challenge of, firstly, squeezing water inside carbon nanotubes, a typically hydrophobic material, and, secondly, measuring the interactions inside this tiny space was huge. But the MIT researchers rose to it.

[ALSO SEE] Three facts that prove water doesn’t play by the rules

Highly sensitive imaging systems were used to measure temperature and behaviour of water inside the carbon nanotubes. The technique called vibrational spectroscopy can not only detect the presence of water in the tube, but also its phase changes. Concerning the water’s phase trapped inside the tubes, the MIT researchers are still reserved. They don’t want to call it ice yet because the crystalline structure is unknown but it’s definitely a solid. “It’s an ice-like phase,” Strano said in a statement. 

The behaviour change directly depends on the diameter of the tubes. Even a tiny difference between nanotubes 1.05 nanometers and 1.06 nanometers resulted in a difference of tens of degrees in the apparent freezing point. “All bets are off when you get really small,” Strano says. “It’s really an unexplored space.”

Besides being an excellent science experiment, the MIT research could actually lead to a new class of materials. To liquefy in this state, the water needs to reach temperatures exceeding its boiling point at sea level. This suggests that at room temperature, it will stay solid. It’s not just water — anything can be squeezed inside, theoretically. One potential application is ‘ice wires’ — cables with carbon nanotubes which trap ice inside. Previous research suggests ice can conduct protons 10 times better than conventional conductors.

 

A highly pure array of carbon nanotubes was deposited onto 1 inch by 1 inch substrates. The resulting nanotube transistors outperformed the silicon transistors used for the benchmark. Credit: Stephanie Precourt

Carbon nanotube transistor outperform silicon for the first time — a turning point in electronics

A highly pure array of carbon nanotubes was deposited onto 1 inch by 1 inch substrates. The resulting nanotube transistors outperformed the silicon transistors used for the benchmark. Credit: Stephanie Precourt

A highly pure array of carbon nanotubes was deposited onto 1-inch by 1-inch substrates. The resulting nanotube transistors outperformed the silicon transistors used for the benchmark. Credit: Stephanie Precourt

Theoretically speaking, carbon nanotubes are some of the best electrical conductors ever discovered. Transistors made out of these one-atom-thick rolls of carbon ought to be five times faster or five times more efficient than silicon transistors — a holy grail in electronics given silicon is very close to reaching its peak performance. But despite decades of research, carbon nanotubes have failed to live up to this hype — until now. Researchers at the University of Wisconsin–Madison report for the first time carbon nanotube transistors that outperform state-of-the-art silicon transistors.

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

The process

The biggest challenges researchers face when using carbon nanotubes for electronics is purity. The tubes need to be as pristine as possible for their stellar properties to shine, otherwise they massively underperform. Specifically, metal impurities are the worst since these act like copper wires and disrupt the semiconductor properties (switching current on and off).

Using polymers and a novel technique, the UW-M researchers isolated semiconducting nanotubes with an unprecedented degree of purity — the solution has only 0.01 percent metallic nanotubes.

Another thing that stands in the way of carbon nanotube transistors is their arrangement. When you assemble carbon nanotubes on a wafer, these need to be spaced by just the right distance and in the right order. This has proven very difficult to control as we’re in the nanorange, or scales hundreds of times smaller than the thickness of a human hair.

This challenge was overcome using a technique invented in 2014 called “floating evaporative self-assembly”. This is a self-assembly phenomenon triggered by rapidly evaporating a carbon nanotube solution.

Of course, the previous process used to isolate the semiconducting nanotubes also insulates the tubes from the conducting electrodes. The team solved this minor setback by baking the insulating layer in a vacuum oven which removed this insulating interface.

Finally, a treatment is applied to remove any leftover impurities and residues from the tubes after they’ve been processed in a solution.

Dawn of a new era

When the carbon nanotube transistor was benchmarked against a silicon transistor of the same size, geometry and leakage current, the former achieved current that’s 1.9 times higher than the latter. This marks the first time that carbon naotubes outperfom silicon transistors — a milestone which might finally spur manufacturers to adopt carbon nanotubes at a commercial scale.

The most interesting short-term applications are for wireless communications technologies that require a lot of current flowing across a relatively small area. In the long-run, a decade from now, carbon nanotubes might become ubiquitous in computing. There are also applications in energy since carbon nanotubes can up the efficiency of solar panels.

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

Next on the drawing board is scaling down the transistors from the one by one-inch wafer they’ve experimented to match the miniature silicon variety used commercially nowadays. There’s also a plan to experiment with these carbon nanotubes in high-performance radio frequency amplifiers.

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

The new design uses a special material called carbon nanotubes, which allows memory and processor layers to be stacked in three dimensions. Image: Max Shulaker

3D stacked computer chips could make computers 1,000 times faster

Computer chips today have billions of tiny transistors just a few nanometers wide (a hair is 100nm thick), all crammed up in a small surface. This huge density allows multiple complex operations to run billions of times per second. This has been going on since the ’60s when Gordan Moore first predicted that  the number of transistors on a given silicon chip would roughly double every two years. So far, so good – Moore is still right! But for how long? There’s only so much you can scale down a computer chip. At some point, once you cross a certain threshold, you pass from the macroworld into the spooky domain of quantum physics. Past this point, quantum fluctuations might render the chips useless. Moore might still be right, though. Or he could be wrong, but in a way that profits society: computer chips could increase in computer power at a far grater pace than Moore initially predicted (if you still keep Moore’s law but replace transistors with the equivalent computing power). This doesn’t sound so crazy when you factor in quantum computers or, more practical, a 3D computer architecture demonstrated by a team at Stanford University which crams both CPU and memory into the same chip. This vastly reduces the “commuting time” electrons typically have to go through while traveling through conventional circuits and makes them more efficient. Such a 3D design could make a chip 1,000 faster than what we typically see today, according to the researchers.

 The new design uses a special material called carbon nanotubes, which allows memory and processor layers to be stacked in three dimensions. Image: Max Shulaker

The new design uses a special material called carbon nanotubes, which allows memory and processor layers to be stacked in three dimensions. Image: Max Shulaker

According to Max Shulaker, one of the designers of the chip, the breakthrough lies in interweaving memory (store data) and processors (compute date) into the same space. That’s because, Shulaker says, the greatest barrier that’s holding today’s processors from reaching higher computing speeds lies not with transistors but with memory. As a computer shuttles vasts amounts of data, it constantly dances electrons between storage mediums (hard drives and RAM) and the processors through data highways (the wires).  “You’re wasting an enormous amount of power,” said Shulaker at the  “Wait, What?” technology forum hosted by DARPA. Basically, 96% of the time a computer stays idle, waiting for information to be retrieved. So, what you do is you put the RAM and processor together.

Sounds simple enough, but in reality there are a number of challenges. One of them is that you can’t put the two on the same silicon wafer. During manufacturing, these wafers are heated to 1,000 degrees Celsius, far too much for the metal parts that make up hard drives or solid state drives. So, the workaround was found to be using a novel material: carbon nanotubes –  tubular cylinders of carbon atoms that have extraordinary mechanical, electrical, thermal, optical and chemical properties. Because of their electrical properties similar to silicon, many believe someday these could replace silicon as the de facto semiconductor building block of choice. In this particular case, carbon nanotubes can be processed at low temperatures.

The challenge with working with nanotubes is these are very difficult to ‘grow’ in a predictable, regular pattern. They’re like spaghetti, but in computing if only a couple of your nanotubes are misaligned this spells disaster. Also, inherent defects in manufacturing means that while most CNTs will work as semiconductors (switch current on/off), some will work as conductors and fry your transistors. Luckily, the Stanford researchers found a nifty trick: turn off all the CNTs then run a powerful current through the circuit to blow off the defective conductive CNTs, just like fuses.

The image on the left depicts today’s single-story electronic circuit cards, where logic and memory chips exist as separate structures, connected by wires. Like city streets, those wires can get jammed with digital traffic going back and forth between logic and memory. On the right, Stanford engineers envision building layers of logic and memory to create skyscraper chips. Data would move up and down on nanoscale “elevators” to avoid traffic jams. Credit: Wong/Mitra Lab, Stanford

The image on the left depicts today’s single-story electronic circuit cards, where logic and memory chips exist as separate structures, connected by wires. Like city streets, those wires can get jammed with digital traffic going back and forth between logic and memory. On the right, Stanford engineers envision building layers of logic and memory to create skyscraper chips. Data would move up and down on nanoscale “elevators” to avoid traffic jams. Credit: Wong/Mitra Lab, Stanford

 

Ultimately, the Stanford team built a system that stacks memory and processing power in the same unit, with tiny wires connecting the two. The architecture can produce lightning-fast computing speeds up to 1,000 times faster than would otherwise be possible. To demonstrate, they used this architecture to devise sensors that detect anything from infrared light to various chemicals.

So, when will we see stacked interfaces like these in our computers or smartphones? Nobody knows for sure due to one issue: cooling. We’ve yet to see a solution that works well for a 3D stacked CPU-memory unit.

This illustration represents the four-layer prototype high-rise chip built by Stanford engineers. The bottom and top layers are logic transistors. Sandwiched between them are two layers of memory. The vertical tubes are nanoscale electronic "elevators" that connect logic and memory, allowing them to work together to solve problems. Credit: Max Shulaker, Stanford

Stacked “high-rise” computer chips add a new dimension to manufacturing

Moore’s law says that the number of transistors in an integrated circuit doubles every two years, hence doubling also the computing power. Since it was first predicted in 1965, this trend has hold true allowing computers to evolve at an exponential rate. To support the law, scientists tweak one or all of these three main manufacturing parameters: chip size, speed and price. Now, a new dimension might be factored in: tallness.

Making chips in 3-D

Researchers at Stanford University show how this might happen after they revealed a novel manufacturing technique which can be used to make multi-story logic and memory chips. Of course, scaling chips vertically has been considered before but it wasn’t until recently that the numerous challenges that come with it were overcome. The main issues are operating temperature (lost electrons transform into heat and the more circuits you have packed the more heat generated) and so-called traffic jams that happen when computers get too busy.

This illustration represents the four-layer prototype high-rise chip built by Stanford engineers. The bottom and top layers are logic transistors. Sandwiched between them are two layers of memory. The vertical tubes are nanoscale electronic "elevators" that connect logic and memory, allowing them to work together to solve problems. Credit: Max Shulaker, Stanford

This illustration represents the four-layer prototype high-rise chip built by Stanford engineers. The bottom and top layers are logic transistors. Sandwiched between them are two layers of memory. The vertical tubes are nanoscale electronic “elevators” that connect logic and memory, allowing them to work together to solve problems. Credit: Max Shulaker, Stanford

The approach ingeniously stacks both logic and memory chips atop one another, interconnecting them with thousands of nanoscale electronic “elevators” that move data fast between the layers. This would allow data to flow  faster and using less electricity, than the traditional bottle-neck prone wires connecting single-story logic and memory chips today.

“This research is at an early stage, but our design and fabrication techniques are scalable,” said  Subhasish Mitra, a Stanford professor of electrical engineering and computer science. “With further development this architecture could lead to computing performance that is much, much greater than anything available today.”

The de facto material used for making transistors and computer chips today is silicon. The material has proven to be a great fit for the electronics industry, but it’s now nearing the full extent of its capabilities. One problem with silicon is heat. We all feel this when we hold a smartphone and put our hands over a computer. This heat is in fact electricity that leaks out of the silicon transistors. To solve this problem, Stanford researchers turned to carbon nanotubes

Carbon Nanotubes (CNTs) and their compounds exhibit extraordinary electrical properties for organic materials, and have a huge potential in electrical and electronic applications such as photovoltaics, sensors, semiconductor devices, displays, conductors, smart textiles and energy conversion devices (e.g., fuel cells, harvesters and batteries). They are so slender that nearly 2 billion CNTs could fit within a human hair. Because of their tiny diameter, CNTs are thought to lose less electrons, but packaging enough of them to became effective has proven to be difficult.

Mitra and colleagues employed a nifty trick. They started by growing CNTs the standard way, on round quartz wafers, then added a metal film that acts like a tape. Just like an adhesive, when a silicon wafer was  placed atop, the CNTs came off the quartz growth medium. To make sure they made a CNT layer with sufficient density the lift and deposit technique was repeated 13 times. The researchers report  they achieved some of the highest density, highest performance CNTs ever made – an impressive feat considering they didn’t have  sophisticated equipment at their disposal like those at a commercial plant.

The CNTs were only one part of the equation – the logic part for the transistors. They still had to figure out how to make memory for vertical chips. So, again they devised a storage medium that isn’t based on silicon, like most of today’s RAM. Instead, the Stanford team fabricated memory using titanium nitride, hafnium oxide and platinum. This formed a metal/oxide/metal sandwich. Applying electricity to this three-metal sandwich one way causes it to resist the flow of electricity. Reversing the electric jolt causes the structure to conduct electricity again. Changing from resistance to flow is how this new memory type creates digital zeroes and ones, hence the name resistive random access memory, or RRAM.

Authors write that RRAM uses less energy, which translates into a prolonged battery life for smartphones or notebooks.

The image on the left depicts today's single-story electronic circuit cards, where logic and memory chips exist as separate structures, connected by wires. Like city streets, those wires can get jammed with digital traffic going back and forth between logic and memory. On the right, Stanford engineers envision building layers of logic and memory to create skyscraper chips. Data would move up and down on nanoscale "elevators" to avoid traffic jams. Credit: Wong/Mitra Lab, Stanford

The image on the left depicts today’s single-story electronic circuit cards, where logic and memory chips exist as separate structures, connected by wires. Like city streets, those wires can get jammed with digital traffic going back and forth between logic and memory. On the right, Stanford engineers envision building layers of logic and memory to create skyscraper chips. Data would move up and down on nanoscale “elevators” to avoid traffic jams. Credit: Wong/Mitra Lab, Stanford

Ultimately, Max Shulaker and Tony Wu, Stanford graduate students in electrical engineering, unveiled a four-story high-rise chip at the IEEE International Electron Devices Meeting in San Francisco. There, they explained the key parameter that helped them achieve this amazing feat: manufacturing temperature. Typically, memory or transistors from silicon are manufactured at very high temperatures of around 1,000 degrees Celsius. The Stanford process for making RRAM and CNTs uses low temperature so they could stack memory and logic boards atop one another without risking melting anything below.

Now, imagine not four but eight, sixten or 512 of these layers stacked. You’d get a chip that’s 512 times more powerful than the same ones found today that occupy the same surface area. Truly, this has the potential to change computing. Before you make your hopes up for a quantum computer of your own at home (better wait until someone actually makes one in the lab first), you might want to consider paying more attention to this sort of advances.

 

Modern Blacksmithery: forging a 320 Layer Damascus Steel Blade

In the Middle Ages, Blacksmiths were highly regarded, and this was one of the most active industries. Nowadays, with modern technology, blacksmiths are all but extinct; yet some of them are still forging, working on spectacular blades. Here is such an example:

Damascus steel was a type of steel used in Middle Eastern swordmaking. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water. Blades with Damascus steel are especially resilient, and the reputation of this steel has given rise to many legends, such as the ability to cut through a rifle barrel or to cut a hair falling across the blade.

A study conducted in Germany in 2006 revealed that Damascus steel contains nanowires and carbon nanotubes, generated through the forging process. The team of researchers was based at the Technical University of Dresden and they used x-rays and electron microscopy to examine Damascus steel discovering the presence of cementite nanowires.

A Damascus Blade

A Damascus Blade

A sample of the new material. Image credit: Surrey Nanosystems

Blackest material resembles a black hole. It’s so black you can’t even see it

A sample of the new material. Image credit: Surrey Nanosystems

A sample of the new material. Image credit: Surrey Nanosystems

You might have thought black is too solemn or boring, but you may just change your mind. Through careful material science manipulation, involving thousands of tightly packed carbon nanotubes, British company Surrey NanoSystems made a super black coating that absorbs almost 99.96%  of visual light – a world record. Practically only a tiny fraction of the visual spectrum is reflected, so the only thing our eyes can discern is a bizarre abyss, akin to a black hole.

Dubbed Vantablack, the coating is made up of carbon nanotubes – rolled-up sheets of carbon 10,000 thinner than a strand of human hair – that are so tightly packed together that light can’t pass through. It’s only the ultra-short wavelength light that peers through, but that’s far from being enough to actually make the material look like … anything but void.

The nanotubes were grown on sheets of aluminium, but even if you fold and twist the Vantablack material in any direction any shapes, counters or depth become entirely lost because of the material’s light absorbing capabilities.

“You expect to see the hills and all you can see … it’s like black, like a hole, like there’s nothing there. It just looks so strange,” said Ben Jensen, the firm’s chief technical officer.

The material will be used to calibrate optical instruments like astronomical cameras, telescopes and infrared scanning systems to get better readings. Also, because it’s SO black, the material conducts heat seven and a half times more effectively (remember Planck’s law) than copper and has 10 times the tensile strength of steel (an inherent property of carbon nanotubes).

“It reduces stray-light, improving the ability of sensitive telescopes to see the faintest stars, and allows the use of smaller, lighter sources in space-borne black body calibration systems. Its ultra-low reflectance improves the sensitivity of terrestrial, space and air-borne instrumentation”, said Jensen in a release.
“Many people think black is the absence of light. I totally disagree with that. Unless you are looking at a black hole, nobody has actually seen something which has no light,” professor of colour science and technology Stephen Westland from Leeds University in the UK told The Independent. “These new materials, they are pretty much as black as we can get, almost as close to a black hole as we could imagine.”

The Vantablack coating was described in a paper published in the journal Optics Express.

Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions — air, argon, nitrogen and a vacuum — to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University)

Carbon nanotube fiber can carry four times more charge than copper

Reliable, well supplied and with years and years of manufacturing experience behind it, copper is the most widespread material used for delivering electrical charge. Some applications warrant more efficient materials, though,  and researchers at Rice recently showed that carbon nanotubes spun into fiber can carry four times as much electrical charge than copper cables of the same mass.

Of course, carbon nanotubes taken individually can deliver 1,000 times more current than copper, but real-world applications require macroscopic conductors. Previous attempts at mustering carbon nanotubes for high power electrical charge failed, however Rice University researchers demonstrated that wet-spun carbon nanotube fiber is a good alternative.

Rice professors Junichiro Kono and Matteo Pasquali developed a strong and flexible cable even though at 20 microns wide, it’s thinner than a human hair. For benchmark purposes, the researchers analyzed the “current carrying capacity” (CCC), or ampacity, of the nanotube fiber against that of copper cables. Four mediums were chosen for this analysis: open air, in a vacuum and in nitrogen or argon environments.

Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions — air, argon, nitrogen and a vacuum — to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University)

Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions — air, argon, nitrogen and a vacuum — to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University)

The number one cause of electrical cable failure is overheating. When current passes through a conductor, it also produces heat because of the material’s resistivity. When temperatures exceed rated values, the cable gets too hot, breaks and, of course, can potentially become a fire hazard. Concerning the carbon nanotube fibers, those working in nitrogen atmosphere proved to have the best CCC, followed   by argon and open air, all of which were able to cool through convection. The same nanotube fibers in a vacuum could only cool by radiation and had the lowest CCC.

“The outcome is that these fibers have the highest CCC ever reported for any carbon-based fibers,” Kono said. “Copper still has better resistivity by an order of magnitude, but we have the advantage that carbon fiber is light. So if you divide the CCC by the mass, we win.”

Ever carried a copper or aluminium cable? That’s some heavy gear, but not because of the conducting material itself, but rather because both copper and aluminium don’t have a high tensile strength, a heavy steel-core reinforcement is needed to support the cable. In applications where weight is an important factor to consider, like aerial or spacial projects, carbon nanotube fiber could prove to be a better option, according to the Rice scientists.

Pasquali even suggested the thread-like fibers are light enough to deliver power to aerial vehicles. We’ve heard of wackier stuff work.

 “Suppose you want to power an unmanned aerial vehicle from the ground,” he mused. “You could make it like a kite, with power supplied by our fibers. I wish Ben Franklin were here to see that!”

Details were published in the journal Nanoscale. [story via Kurzeweil]

The carbon nanotube array is arranged as horizontal over vertical tubes in a chamber that is filled metal in gaseous form. The tubes' internal resistivity to electron flow causes them to heat more at the junction. (Credit: Joseph W. Lyding/University of Illinois)

New technique that allows self-soldering of carbon nanotubes may help replace silicon transistors

Carbon nanotubes and graphene have been hailed time and again as the wonder materials that will change the face of technology in the future. Before silicon can be dethroned from its reigning position, however, a lot of manufacturing issues need to be addressed. A new technique developed by researchers at University of Illinois provides a simple and straight-forward way of soldering carbon nanotubes together, that is consistent with current manufacturing technologies and thus inexpensive. The method basically allows researchers to arrange carbon nanotubes for use as transistors where they could be embedded into thin sheets of plastic or flat-panel displays and effectively allow highly flexible electronics to be made, where silicon is currently unsuited for.

Carbon nanotubes, as the name implies, are extremely thin  tube-shaped materials, made of carbon, having a diameter measuring on the nanometer scale.  A nanometer is one-billionth of a meter, or about one ten-thousandth of the thickness of a human hair.  The graphite layer appears somewhat like a rolled-up chicken wire with a continuous unbroken hexagonal mesh and carbon molecules at the apexes of the hexagons. Carbon nanotubes are extremely sought after because of their amazing properties. For instance you can construct them with length-to-diameter ratio of up to 132,000,000:1! Where they truly sparkle, however, is in their fantastic electrical conductivity properties, so naturally they’re seen as great contenders for the material that will dominate the technological age of tomorrow.

To make transistors out of carbon nanotubes is very difficult as of now, unfortunately. In an array of nanotubes, to make transistors, you need to slow down or stop the current altogether at junctions. In a standard circuit, the connecting wires are soldered together, but with nanotubes we’re talking on an extremely minuscule scale. Not even the tinniest soldering iron in the world could help you out. When there’s a will, there’s a way, though – you just need to think outside the box.

[ALSO READ] First computer made out of carbon nanotubes spells silicon demise in electronics 

Joseph Lyding, a professor of electrical and computing engineering at University of Illinois, along with colleagues have found one such way of soldering carbon nanotubes. Though carbon nanotubes have amazing electrical conductivity properties, that doesn’t mean that they’re superconductive too. As current passes through them, some of that energy is lost as heat which causes a temperature gradient in their vicinity. In a stroke of ingenuity, the researchers controlled chemical reactions that occur at certain temperatures to happen only in certain hot spots. This caused tiny amounts of metal to deposit in this spots – just enough to solder nanotube junctions. The  technique is called CVD [chemical vapor deposition] and is currently widely used by most major manufacturing companies. This means that, if they wish it in the future, they can integrate this process with existing technology dramatically cutting the huge costs that are associated with replacing infrastructure.

“Other methods have been developed to address the nanotube junction resistance problem, but they are generally top-down and quite slow,” Lyding said. “Our method is self-aligned and self-limiting and is therefore easily implemented.”

Here’s an illustrated view of the carbon nanotube self-soldering process, which only lasts a few seconds but improves device performance by a whole order of magnitude.

Step 1

 The carbon nanotube array is arranged as horizontal over vertical tubes in a chamber that is filled metal in gaseous form. The tubes' internal resistivity to electron flow causes them to heat more at the junction. (Credit: Joseph W. Lyding/University of Illinois)

The carbon nanotube array is arranged as horizontal over vertical tubes in a chamber that is filled metal in gaseous form. The tubes’ internal resistivity to electron flow causes them to heat more at the junction. (Credit: Joseph W. Lyding/University of Illinois)

Step 2

The gas molecules surrounding the nanotubes react to the heat and depose on the hot spots, soldering the junctions. The resistance then drops, cooling the junction and effectively stopping the reaction. (Credit: Joseph W. Lyding/University of Illinois)

The gas molecules surrounding the nanotubes react to the heat and depose on the hot spots, soldering the junctions. The resistance then drops, cooling the junction and effectively stopping the reaction. (Credit: Joseph W. Lyding/University of Illinois)

Step 3

Finally, this how the  metallized nanotube-nanotube junctions look like.  (Credit: Joseph W. Lyding/University of Illinois)

Finally, this how the metallized nanotube-nanotube junctions look like. (Credit: Joseph W. Lyding/University of Illinois)

The findings were reported in the journal Nano Letters.

Carbon_nanotube_working_computer

First computer made out of carbon nanotubes spells silicon demise in electronics

Carbon_nanotube_working_computer

In an inspiring breakthrough, Stanford researchers have created the first ever working computer made entirely out of carbon nanotubes. The technology is still very infant, as the computer  operates on just one bit of information, and can only count to 32. Theoretically, however, it can be scaled up to perform billions of operations given enough memory.  With more refining, computers such as these hint towards a new digital age where carbon nanotubes reign supreme and silicon models are obsolete.

The prototype was dubbed “Cedric” and was made part of an extensive collaborative effort. Scientists have been trying to develop a working carbon nanotubes (CNTs) based machine for years, however past attempts have failed. The interest is huge because CNTs offer a wide array of intrinsic material properties far superior to silicon, the currently industry standard used in electronics. CNTs are basically rolled-up tubes of pure carbon only one atom thick. They’re fantastic electrical conductors and due to their incredible thinness, these can be employed as very efficient semiconducting materials capable of switching on and off electrical current flowing through very fast – a property indispensable for building working transistors.

Not that fast, not that stupid either

Wafer filled with CNTs transistors.

Wafer filled with CNTs transistors.

A number of challenges have kept previous attempts for developing a working computer from CNTs. For one, transistors made out of CNTs have been around for some 15 years already, the biggest problem however is lining and connecting these up. When CNTs are put on a wafer these aren’t perfectly aligned, and as such a machine would rend errors. The Stanford scientists used a method however that built chips with CNTs which are 99.5% aligned. What about the remaining 0.5%? Of course, the scientists din’t ignore this offset – after all it would have introduced a significant error in the resulting machine’s computations. Instead, they developed a neat algorithm that factored these misalignment our of computations.

Then, a second imperfection had to be overcome. Some of the CNTs have an inherent manufacturing imperfection that makes them exclusively metallic instead of semiconducting. This means these flawed CNTs always conduct electricity which is a big problem. The researchers employed an extremely simple, yet ingenious trick to overcome this. Since they could switch on or off the good, semiconducting CNTs, the researchers switched these off and pumped a lot of current into the circuit. The good CNTs weren’t touched at all since these were switched off, while the flawed CNTs vaporized from all the energy that went through. A perfect method for filtering out the flawed tubes. In the end they assembled their machine – Cedric – which works perfectly with no errors, even if it can only count on two hands.

“People have been talking about a new era of carbon nanotube electronics, but there have been few demonstrations. Here is the proof,” said Prof Subhasish Mitra, lead author on the study.

“These are initial necessary steps in taking carbon nanotubes from the chemistry lab to a real environment,” said Supratik Guha, director of physical sciences for IBM’s Thomas J Watson Research Center.

Scaling Cedric to count billions

So far, Cedric is only a proof of concept and it’s quite bulky even by silicon standards – eight microns fat. Shrinking down the transistors will be the next obvious step. This doesn’t mean that it’s a sort of herculean task. Far from it – the technology necessary to scale up Cedric to say 64 bit with nanoscale transistors is well in place. It’s just a matter of trial and error before the scientists can get this moving. In a matter of years we may actually be able to type on a CNTs computer. In fact Cedric is already capable of achieving any task – it just needs more memory!

“In terms of size, IBM has already demonstrated a nine-nanometre CNT transistor.

“And as for manufacturing, our design is compatible with current industry processes. We used the same tools as Intel, Samsung or whoever.

“So the billions of dollars invested into silicon has not been wasted, and can be applied for CNTs.”

Silicon, the most employed material in electronics, has served mankind well. It’s cheap, durable and efficiency, however the material is reaching it’s absolute limits. It can only be shrunk so much, and for computing power to grow you need as many transistors as you can crammed up on minimally large surface. Carbon nanotubes are considered key by many industry experts into breaching the silicon limit and allow Moore’s law to still remain valid.

 

As cells squeeze through a narrow channel, tiny holes open in their membranes, allowing large molecules such as RNA to pass through. Image: Armon Sharei and Emily Jackson

New method allows large molecules to get squeezed through cell membranes

A group of researchers at MIT have devised a new method for infiltrating cells with large molecules such as nanoparticles or proteins that is a lot more non-intrusive and doesn’t damage the cell. Imaging target cells or growing more stable stem cells might thus be possible with this method.

As cells squeeze through a narrow channel, tiny holes open in their membranes, allowing large molecules such as RNA to pass through. Image: Armon Sharei and Emily Jackson

As cells squeeze through a narrow channel, tiny holes open in their membranes, allowing large molecules such as RNA to pass through.
Image: Armon Sharei and Emily Jackson

Every cell has a membrane, which is put to great use as it protects the cell’s inner environment by regulating what gets in and what gets out. Typically, you don’t want foreign molecules entering your cells, but sometimes you do. Various methods have been employed to breach cell membranes and introduce other bodies, however these tend to be intrusive and sometimes can lead to the damaging and even destruction of the cell.

The MIT method of introducing large molecules in cell is a lot safer and efficient and implies squeezing the cell through a narrow construction just enough for tiny, yet temporary, gaps to surface. Prior to squeezing the cell, large molecules – be it RNA, proteins or nanoparticles – are tasked to float outside cell, such that when the holes pop these slide through the membrane instantly.

Through this technique the MIT researchers were able to deliver reprogramming proteins which turned the target cells into pluripotent stem cells – notoriously difficult to generate efficiently – with a success rate 10 to 100 times better than any other existing method. A simply massive advancement. Also, they’ve also tested the method with other large molecules like special nanoparticles, like carbon nanotubes or quantum dots, to image cells and thus monitor their activity.

“It’s very useful to be able to get large molecules into cells. We thought it might be interesting if you could have a relatively simple system that could deliver many different compounds,” says Klavs Jensen, the Warren K. Lewis Professor of Chemical Engineering, professor of materials science and engineering, and a senior author of a paper describing the new device in this week’s issue of the Proceedings of the National Academy of Sciences.

The team’s fantastic research builds upon previous work, when Jensen and Robert Langer, the David H. Koch Institute Professor at MIT and also a study lead author, forced molecules into cells as they flowed through a microfluidic device. The process was slow and not very effective, but it was during this time that the researchers learned that if you squeeze a cell just right now, tiny holes will appear – pure windows of opportunity.

Capitalizing on this, the scientists then proceeded to adjust their set-up and devised some rectangular microfluidic chips, no larger than a quarter, fitted with 40 to 70 parallel channels.  Cells are suspended in a solution with the material to be delivered and flowed through the channel at high speed — about one meter per second. Halfway through the channel, the cells pass through a constriction about 30 to 80 percent smaller than the cells’ diameter. The cells don’t suffer any irreparable damage, and they maintain their normal functions after the treatment.

“This appears to be a very broadly applicable approach for loading a diversity of different compounds into a diversity of different cells,” says Mark Prausnitz, a professor of chemical and biomolecular engineering at Georgia Tech, who was not part of the research team. “It’s a really nice example of taking devices from the world of engineering and microelectronics and using them in quite different ways to solve problems in medicine that could have really great impact.”

 

source: MIT

Nanootech yarn muscle

Super-strong artificial muscles made from nanotech yarn

Scientists at University of Texas Dallas have made artificial muscles capable of supporting 100,000 times their own weight and generate 85 times more mechanical power than natural muscle of the same size. Applications for this kind of technology are quite numerous, ranging from extremely strong and intelligent textiles to high-temperature applications since the fabric has a negative thermal expansion coefficient.

Nanootech yarn muscle

The diameter of this coiled yarn is about twice the width of a human hair. (c) UT Dallas

The artificial muscles were constructed from carbon nanotubes, tiny hallow cylinders made from the same made from the same type of graphite layers found in the core of ordinary pencils. The nanotubes were put together as to constitute a string of yarn. The yarn was infiltrated with simple paraffin wax, commonly found in candles, and then twisted. Because the wax is a “volume changer”, when the composite twisted yarn was heated either electrically or using a flash of light the wax expanded. As such the yarn volume increased, and the yarn length contracted.

“The artificial muscles that we’ve developed can provide large, ultrafast contractions to lift weights that are 200 times heavier than possible for a natural muscle of the same size,” said Dr. Ray Baughman, team leader, Robert A. Welch Professor of Chemistry and director of the Alan G. MacDiarmid NanoTech Institute at UT Dallas. “While we are excited about near-term applications possibilities, these artificial muscles are presently unsuitable for directly replacing muscles in the human body.”

Smart fabric made out of nanotech yarn

Muscle contraction – also called actuation – can be ultrafast, occurring in 25-thousandths of a second. Including times for both actuation and reversal of actuation, the researchers demonstrated a contractile power density of 4.2 kW/kg, which is four times the power-to-weight ratio of common internal combustion engines.

“Because of their simplicity and high performance, these yarn muscles could be used for such diverse applications as robots, catheters for minimally invasive surgery, micromotors, mixers for microfluidic circuits, tuneable optical systems, microvalves, positioners and even toys,” said Baughman.

For instance, because of their ultra-fast expansion/contraction to slight temperature changes, the artificial muscles could be employed in smart clothing whose textile porosity could change in order to provide thermal or chemical comfort. The yarn can be easily twisted together, woven, sewn, braided and knotted.

Also the yarn has been found to contract only by 7% when lifting heavy loads at a whooping 2,500 degrees Celsius – that’s 1000 degrees past the melting point of steel, where no other high-work-capacity actuator has been able to survive.

“The remarkable performance of our yarn muscle and our present ability to fabricate kilometer-length yarns suggest the feasibility of early commercialization as small actuators comprising centimeter-scale yarn length,” Baughman said. “The more difficult challenge is in upscaling our single-yarn actuators to large actuators in which hundreds or thousands of individual yarn muscles operate in parallel.”


The findings were reported in the journal Science,

source

This shows the new all-carbon solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. Credit: Mark Shwartz / Stanford University

First all-carbon solar cell promises to lower industry cost

Scientists at Stanford University have successfully devised the world’s first solar cell made entirely out of carbon. This alternative to typical silicon solar panels is not only a lot cheaper to produce, but also a lot less simpler to use. Such carbon cells can be coated on any surface and turn it into a solar panel, be it windows, roof tops and so on.

“Carbon has the potential to deliver high performance at a low cost,” said study senior author Zhenan Bao, a professor of chemical engineering at Stanford. “To the best of our knowledge, this is the first demonstration of a working solar cell that has all of the components made of carbon. This study builds on previous work done in our lab.”

This shows the new all-carbon solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. Credit: Mark Shwartz / Stanford University

This shows the new all-carbon solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. Credit: Mark Shwartz / Stanford University

A solar cell is made out of a photoactive layer, sandwiched between two electrodes. As light hits the the photoactive layer, photons are sucked in and turned into electrons. Typically, the electrode bottom and top layers are made out of  indium tin oxide (ITO), a very rare and expensive material. The Stanford scientists chose to take an alternate, more sustainable path by using carbon, a low-cost and Earth-abundant material.

Bao and colleagues replaced the ITO used in conventional electrodes with graphene – sheets of carbon that are one atom thick –and single-walled carbon nanotubes that are 10,000 times narrower than a human hair. “Carbon nanotubes have extraordinary electrical conductivity and light-absorption properties,” Bao said.

As for the photoactive layer, the researchers used  a new material comprised of buckyballs and carbon nanotubes. The carbon films can be made from thin solution can be coated on any surface, which makes it a highly versatile solution. I know this sounds too good to be true, truth is it still is. It’s main drawback is in its efficiency  – only 1% which is really, really low by any standards. This is because the carbon film  primarily absorbs near-infrared wavelengths of light.

“We clearly have a long way to go on efficiency,” Bao said. “But with better materials and better processing techniques, we expect that the efficiency will go up quite dramatically.”

The researchers are now experimenting with carbon nanomaterials that can absorb a broader spectrum of light, including the visible spectrum. This should kick up the efficiency a notch or two. Despite this, however, as they are currently they could still become viable, since they can make up in volume, where they lack in efficiency.

“Photovoltaics will definitely be a very important source of power that we will tap into in the future,” Bao said. “We have a lot of available sunlight. We’ve got to figure out some way to use this natural resource that is given to us.”

Findings were published in the journal ACS Nano.

 

MIT scientists have devised a new technique for carbon nanotube sensors, as simple as etching on a sheet of paper. (c) Jan Schnorr

Carbon nanotubes drawn with a pencil render cheap and reliable sensors

Researchers at MIT have developed a novel technique of creating cheap and reliable sensors for toxic gases by simply etching carbon nanotubes with a mechanical pen on a special paper, fitted with electrodes. The method allows for easy to make, cheap and reliable sensors that detect noxious gases in the environment, without the hassle that usually follows carbon nanotube manufacturing.

MIT scientists have devised a new technique for carbon nanotube sensors, as simple as etching on a sheet of paper. (c) Jan Schnorr

MIT scientists have devised a new technique for carbon nanotube sensors, as simple as etching on a sheet of paper. (c) Jan Schnorr

Instead of graphite, MIT chemists developed a special pencil lead made out of compressed carbon nanotube powder, which can be used with any kind of mechanical pencil. A carbon nanotube is a tube shaped carbon molecule arranged in a hexagon lattice, only one nanometer in diameter or 50,000 times thinner than a human hair. Using the pencil,  Timothy Swager, the lead researcher, and colleagues, inscribed a sheet of paper, fitted with electrodes made out of gold. An electrical current was then applied to the sheet of paper, and measured as it flows through the carbon nanotube strip, now transmuted into a resistor.  Many gases bind to the carbon atoms in the carbon nanotubes, and thus disrupt electrical flow. By detecting this flow disruption, the presence of the gas can be determined.

For their research, the MIT scientists focused on detecting minute quantities of ammonia, a highly dangerous gas, but they claim the system can easily be adapted to a slew of gases. Two major advantages of the technique are that it is inexpensive and the “pencil lead” is extremely stable, says Swager. On top of that, conventional carbon nanotube sensors rely on hazardous manufacturing techniques likedissolving nanotubes in a solvent such as dichlorobenzene  – the present research  uses a solvent-free fabrication method.

“I can already think of many ways this technique can be extended to build carbon nanotube devices,” says Zhenan Bao, an associate professor of chemical engineering at Stanford University, who was not part of the research team. “Compared to other typical techniques, such as spin coating, dip coating or inkjet printing, I am impressed with the good reproducibility of sensing response they were able to get.”

The carbon nanotube sensor was described in the journal Angewandte Chemie

source: MIT

Electron micrograph of a carbon nanotube resonator. (c) Universitat Autònoma de Barcelona

The most sensitive scale in the world can measure to the yoctogram (proton’s mass)

Electron micrograph of a carbon nanotube resonator. (c) Universitat Autònoma de Barcelona

Electron micrograph of a carbon nanotube resonator. (c) Universitat Autònoma de Barcelona

While on the macro-scale conventional scales make us of gravity to measure mass, on the microscale there are a myriad of factors that interfere with measurements. Scientists at Universitat Autònoma de Barcelona have successfully created a scale made out of a single carbon nanotube which can accurately measure the smallest unit of mass, a yoctogram (one septillionth of a gram – 10-24 grams) or the mass of a single proton. That’s 100 times less massive than previous experiments were able to determine.

This incredible sensitivity is made possible by measuring the difference in vibrational frequency. One  single carbon nanotube approximately 150 nanometers (nm) long and 1.7 nm in diameter had both of its ends fixed, while at its center a one nanometer narrow trench was suspended. The nanotube has a resonant vibrational frequency of approximately 2 gigahertz (GHz), so when even the tiniest unit binds to its surface, it causes a change in  resonant frequency, which is used to measure mass. Thus, the mass resolution they achieved is 1.7 yoctograms (1.7 × 10-24 grams) – the mass of a single proton.

To make the rig as accurate as possible, the operation was performed at about 6 degrees above absolute zero, to isolate it from thermal vibrations, and was placed in vacuum to minimise interference from other atom. Due to the extreme sensitivity of the nanotube resonator, the researchers were able to detect individual xenon atoms and naphthalene (C10H8) molecules which adhered to the surface of the nanotube resonator.

“The yoctogram mass sensitivity achieved by the Catalan team is certainly spectacular ‐ the challenge ahead will be to routinely manufacture nanotube sensors at low cost,” says Rachel McKendry, a nanoscientist at University College London.

The Spanish scientists’ device might pose a great potential for measuring very small masses, allowing for extremely high precision in mass spectroscopy, although subatomic particles are out of its range. Also, different elements in a sample, which might differ only by a few protons, could be distinguished by the carbon nanotube resonating scale.

The findings were reported in the journal Nature Nanotechnology.

via Ars Technica

Graphene nanoribbons can be transformed into carbon nanotubes by twisting. Photo: Pekka Koskinen

Scientists discover novel way of making carbon nanotubes

A team of researchers comprised of scientists at the NanoScience Center of the University of Jyväskylä, Finland, and at Harvard University, US, have shown through computer simulations a novel technique for generation nanomaterials. The whole process revolves around the extremely simple idea of twisting narrow graphene nanoribbons until they become rolled up into carbon nanotubes, which are 20 times stronger than steel and offer a diverse array of high-tech application – truly one of the most marvelous materials developed by scientists in the past few decades.

The mechanism is trivial, indeed – twisting a ribbon until it becomes a tube. You can check it out for yourself simply by twisting the end strap of your backpack and see what happens. Being a classical mechanism, it renders the same effect both in the macro- and micro-scale. The mechanism also enables experimental control, which has earlier been impossible.

Graphene nanoribbons can be transformed into carbon nanotubes by twisting. Photo: Pekka Koskinen

Graphene nanoribbons can be transformed into carbon nanotubes by twisting. Photo: Pekka Koskinen

Since their development more than twenty years ago, carbon nanotubes have been described as “rolled-up graphenes”, even though there wasn’t any rolling implied in the manufacturing process. Currently, they’re made by atom-by-atom growth, just like most other nanomaterials available today.

The new technique can be use to make various kinds of novel carbon nanotubes, to encapsulate molecules insides the tubes, or to make tubules from ribbons made out of other planar nanomaterials, opening a new realm of manufacturing possibilities, one that could lead to more affordable nanomaterials.

The results were published in Physical Review B. The research was funded by the Finish Academy.

 

Space Elevator

Going WAY Up? Japanese corporation wants to build space elevator by 2050

This is the kind of engineering feat that sounds so preposterous, so crazy, so … foolish, that it might actually work. A Japanese construction company plans to build an elevator that can lift tourists in space, up to a quarter the distance between Earth and the moon.

While entrepreneurs like Richard Branson or Paul Allen are busy planning exclusive private space flights for the rich, the Japanese are considering another alternative, which isn’t that down to earth at all. The said elevator would carry up to 30 people at a time, travel at 120 mph and take 7 days to reach its destination – 22,370 miles above Earth. I can only presume another 7 days are needed for descent.

Space ElevatorObayashi Corp. has a solid portfolio of impressive skyscrapers under its belt, including, among others, Japan’s tallest building, the Tokyo Sky Tree. This isn’t some kind of fantasy, SciFi project – they actually want to make it work! The Tokyo-based company said its so-called space elevator could be ready in 40 years, if work on construction would being soon enough.

“Humans have long adored high towers,” said Satomi Katsuyama, the project’s leader. “Rather than building it from the earth, we will construct it from the space.”

The concept of a space elevator isn’t something new, either. The idea has been thrown around for more than 100 years now, before space flight was even conceivable. Sure, it was oddball enough to deem who ever proposed it legally insane, however in time many saw the practicability of such an exploit. Heavy cargo, usually transported in space by rockets, could be sent constantly and at a much lower cost, in the long run, using a space elevator.

The company claims that the project is realistically feasible, thanks to the introduction of carbon nanotubes in 1991, which are 20 times stronger than steel. Obayashi intends on stretching a carbon nanotube-made cable 60,000 miles into space, about a quarter of the distance between the Earth and the moon, where it would be jointed to a counterweight. At the other end, ground-side, would lie a spaceport where tourists will be able to embark on the elevator.

The elevator would climb tourists up to 22,370 miles up, where a terminal station will be located, complete with living quarters, while scientists and researchers could go all the way up to the tether. Magnetic linear motors would ensure a steady 125 mph ascending velocity, which would add up to 7 days of continuous climbing.

“We were inspired by construction of Sky Tree,” which will open for business in May, Katsuyama said. “Our experts on construction, climate, wind patterns, design, they say it’s possible.”

The Japanese news site, Daily Yomiuri, reports that the some other organizations have also been studying the development of space elevators, including NASA. The agency actually considered building an elevator leading from Earth to the Moon directly in the 1970s, but hey… it was the 70’s!

“At this moment, we cannot estimate the cost for the project,” an Obayashi official said. “However, we’ll try to make steady progress so that it won’t end just up as simply a dream.”

Nanostructures off a butterfly wings' surface inspire scientists to design the next generation of accurate and sensitive thermal imaging sensors, which could detect inflamed areas in people, or points of friction in machines. (c) Patrick Landmann/Science Photo Librar

Butterfly wings inspire ultra-sensitive infrared thermal imaging

Butterflies are one of the most enchanting beings in the animal kingdom, a symbol of grace and beauty encountered in every art form. From a crawling larva to a majestic winged creature, it’s difficult not to take notice of the similarities between the butterfly’s metamorphosis process and the ups and downs life serves before one may truly find himself. Before we deviate too far into the metaphysical, however, let’s take a look at what makes a butterfly truly special, namely its wings, and how science has learned to capitalize from them.

Nanostructures off a butterfly wings' surface inspire scientists to design the next generation of accurate and sensitive thermal imaging sensors, which could detect inflamed areas in people, or points of friction in machines. (c) Patrick Landmann/Science Photo Librar

Nanostructures off a butterfly wings' surface inspire scientists to design the next generation of accurate and sensitive thermal imaging sensors, which could detect inflamed areas in people, or points of friction in machines. (c) Patrick Landmann/Science Photo Librar

Butterfly wings, along with a peacock’s feathers, are a perfect example of structural colour display. Typically, butterfly wings contain nanostructured chitin which refracts and reflects light in such manner that it confers them the iridescent colour butterflies are known and treasured for. General Electric chemists, based at the company’s Global Research Center in Niskayuna, New York, seized this opportunity and turned these nanostructures into an infrared (IR) detector, which doesn’t require neither cooling or a heat sink.

The team of researchers lead by Radislav Potyrailo, coated the rows of tiny tree-like structures on scales, taken from a butterfly’s wings, with single walled carbon nanotubes (SWNTs) to absorb more infrared radiation. These allowed the butterfly to absorb even more heat, which caused the nano-structures to expand and in the process, altered the reflected light wavelength.

 ‘The chitin-based material of the Morpho tree nanostructures does absorb over the 3-8µm spectral range [the IR spectrum runs from 0.7-300µm],’ explains Potyrailo

Thermal infrared imaging currently has a myriad of applications, ranging from seeing in the dark (thermal night vision goggles) to sensors that check for insulation, however this kind of equipment is extremely complicated to build and expensive.  The General Electric research infrared detector, just less then a micrometer in size, currently has a resolution 20 times sharper than existing detectors, and because of the chitin’s physical properties and its extremely small scale, it can go from cool to hot extremely fast, making it perfect for applications where fleeting changes in temperature, albeit very small (temperature drops no greater than 0.018 °C may be recorded), need to be constantly monitored.

This doesn’t mean though that we’re going to see any butterfly farms that harvest tons of butterfly wings in the near future, though. What a desolate sight that would’ve been. The GE scientists suggest other materials, such as fluoropolymers and silicones, would be far more suited for manufacturing IR imaging gear, actually outperforming the nanostructures based on the butterfly.

 

“We plan that the infrared light will come from one side of the bio-inspired thin film and will heat up the film,’ he says. ‘The other side of the film will be iridescent and iridescence will locally change its colours upon local heating.’

 

source / image

World’s lightest material can really take a hit

Recently, a team of scientists has created a new metallic material which they claim to be the lightest in all the world, not even coming close to styrofoam or aerogels, and even making carbon nanotubes seem heavy.

This lightest material has an estimated density of just of 0.9 milligrams per cubic centimeter (mg/cc), compared with carbon nanotubes, which come at 1.3-mg/cc; it was designed as a joint effort by researchers from HRL, CalTech and the University of California, Irvine. This metallic material is practically made of hollow tubes just 100 nanometers across that are formed in a micro-lattice process; it is 99.99% open volume (air), and perhaps the most interesting fact about it, it is extremely shock absorbent. If you were to crush it even more than halfway through, it would just bounce back to its initial size and shape.

This technology of lightest material was developed with a horde of applications in thought, including “battery electrodes, catalyst supports, and acoustic, vibration or shock energy damping”, but if you ask me, it could be used in so much more than this, including impact technology, saving laptops or phones, earthquake management, and so on.

Captioned above is the Stanford University developed transparent sensor, which is capable of stretching to great lengths without getting deformed. (c) Stanford University

Skin-like material that stretches and senses might bring the tactile to the artificial

Captioned above is the Stanford University developed transparent sensor, which is capable of stretching to great lengths without getting deformed. (c) Stanford University

Captioned above is the Stanford University developed transparent sensor, which is capable of stretching to great lengths without getting deformed. (c) Stanford University

In the new mobile information age where smartphones have become an ever common part of our lives, there seems to be a dominant trend which tends to incorporate interactive touch screen capabilities to more and more consumer electronics. It’s pretty clear that our electronics are getting smarter day by day – I, for one, am still waiting for the next generation of vacuums to outwit me – and as such, the demand for innovative interactive tech is high.

Researchers at Stanford University have made a great forward in this sense after they developed a highly ductile smart-material, filled with sensors, while has the capability to stretch and return to its original size without a problem; much like the human skin. The material is made out of two layers of sillicon, coated by extremely thin single-walled carbon nanotubes, which basically act like two parallel plates. When one of the layers is pressed, the distance between the layers becomes thinner, the capacity of the sensor is increased. Silicone can store electrical charge, and thus whenever this charge is modified by pressing the plates, it is quantified by the sensors which can correlate the charge to a pressure. Basically, the material can feel, or rather sense.

RELATED: Scientists create artificial muscles from nanotubes 

The highly important stretching ability is offered by the carbon nanotubes characteristics. After being sprayed on to the sillicone layer, they randomly positioned themselves. When they are tensioned, the nanotubes stretch orientating towards the stretch direction, only to revert to their exact initial position when released.

The stretchy sensor can detect a wide array of touches, according to Darren Lipomi, a postdoctoral researcher on the team. Just like skin, the material can sense whether it’s being pressed or pinched.

Applications are numerous, the most realistic example being the prosthetic industry. However, think of robots capable of extremely sensitive manipulations, instead of the stiff maneuvers conventional robots have today. You wouldn’t want to shake hands with a robotic arm, nowadays.

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