This method is not only small like the already demonstrated batteries made of nanotubes but it is also very cheap. Like batteries, capacitors hold an electric charge, but for a shorter period of time. However, capacitors can store and discharge electricity much more rapidly than a battery.

The small diameter helps the nanomaterial ink stick strongly to the fibrous paper, making the battery and supercapacitor very durable. The paper supercapacitor may last through 40,000 charge-discharge cycles, which is at least an order of magnitude more than lithium batteries. The nanomaterials also make ideal conductors because they move electricity along much more efficiently than ordinary conductors.

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Cui had previously created nanomaterial energy storage devices using plastics. His new research shows that a paper battery is more durable because the ink adheres more strongly to paper. Furthermore, you can crumple or fold the paper battery, or even soak it in acidic or basic solutions, and the performance does not degrade.

The flexibility of paper allows for many clever applications. “If I want to paint my wall with a conducting energy storage device,” Cui said, “I can use a brush.” In his lab, he demonstrated the battery to a visitor by connecting it to an LED (light-emitting diode), which glowed brightly.

A paper supercapacitor may be especially useful for applications like electric or hybrid cars, which depend on the quick transfer of electricity. The paper supercapacitor’s high surface-to-volume ratio gives it an advantage.

“This technology has potential to be commercialized within a short time,” said Peidong Yang, professor of chemistry at the University of California-Berkeley. “I don’t think it will be limited to just energy storage devices,” he said. “This is potentially a very nice, low-cost, flexible electrode for any electrical device.”

Cui predicts the biggest impact may be in large-scale storage of electricity on the distribution grid. Excess electricity generated at night, for example, could be saved for peak-use periods during the day. Wind farms and solar energy systems also may require storage.

“The most important part of this paper is how a simple thing in daily life – paper – can be used as a substrate to make functional conductive electrodes by a simple process,” Yang said. “It’s nanotechnology related to daily life, essentially.”

“Everybody talks about using hydrogen as a super-green fuel, but actually generating that fuel without using some other non-green energy in the process is not easy,” says Kara Bren, professor in the Department of Chemistry. “People have used sunlight to derive hydrogen from water before, but the trick is making the whole process efficient enough to be useful.”

Bren and the rest of the University of Rochester team will be investigating artificial photosynthesis, which uses sunlight to carry out chemical processes analogous to the ones the plants do. What makes the Rochester approach different from past attempts to use sunlight in order to produce hydrogen from water is that their device is divided into three “modules” that allow each stage of the process to be manipulated and optimized far more easily compared to other existing methods.

The first module uses visible light to create free electrons. A complex natural molecule called a chromophore that plants use to absorb sunlight will be re-engineered to efficiently generate reducing electrons. The second module will be a membrane covered with carbon nanotubes which act as molecular wires so small that they are only one-hundred-thousandth the thickness of a human hair. To prevent the chromophores from re-absorbing the electrons, the nanotube membrane channels the electrons away from the chromophores and toward the third module. In the third module, catalysts put the electrons to work forming hydrogen from water. The hydrogen can then be used in fuel cells in cars, homes, or power plants of the future.

By separating the first and third module with the nanotube membrane, the chemists hope to isolate the process of gathering sunlight from the process of generating hydrogen. This isolation will allow the team to maximize the system’s light-harvesting abilities without altering its hydrogen-generation abilities, and vice versa. Bren says this is a distinct advantage over other systems that have integrated designs because in those designs a change that enhances one trait may degrade another unpredictably and unacceptably.

Bren says it may be years before the team has a system that clearly works better than other designs, and even then the system would have to work efficiently enough to be commercially viable. “But if we succeed, we may be able to not only help create a fuel that burns cleanly, but the creation of the fuel itself may be clean.”

The project has caught the attention of the U.S. Department of Energy, which has just given the team nearly $1.7 million to pursue the design.

The technology is also a potential fit for extreme applications where conventional loudspeakers are likely to get damaged. “It will still emit sound if part of the film is broken, and it can be put on any flexible substrate, such as flags,” said Kaili Jiang, a professor at Tsinghua University in Beijing. He and other researchers from Tsinghua University and Beijing University created the thin CNT films by using two simple electrodes, and several films can be put together to make a large area loudspeaker. A cylindrical cage-like CNT thin film loudspeaker can also be shaped to emit sound in all directions. A sinusoidal voltage is applied across the two electrodes to create clear and loud tones.

Sound generation mechanism of the CNT film can be understood with the aid of a thermo-acoustic picture. The alternating current from the two electrodes periodically heats the CNT thin films, resulting in a temperature oscillation. This fluctuation excites the pressure to oscillate in the surrounding air, resulting in sound generation. The mechanism that produces the sound is not the mechanical movement of the film, but the thermal expansion and contraction of the air in the vicinity of the thin film.

When an alternating current passes through the CNT, the thin film will be heated for the duration of the positive and negative half-cycles. This results in a double frequency temperature oscillation, as well with a double frequency sound pressure.

The most promising property is the stretch-ability of the film. Using springs (which double up as electrodes), the film can be uniformly stretched up to a maximum of 200% of its original size and with this, the film increases in transparency. This see-through feature could enable the CNT film loudspeaker to be adapted to LCD modules. If the loudspeaker film is mounted on top of a LCD module, transmittance is reduced to 80%, with the view being only slightly darker than usual. However, by stretching the film or by administering a laser treatment, the transmittance increases to 95%.

The other important characteristic is the flexibility of the film which can be molded into any shape and placed onto a range of rigid or flexible insulating surfaces. The loudspeaker films can be placed on flags or even on clothes – to create a speaking or singing jacket. With all these incredible future applications, the project has many more hurdles to cross. The CNT would need to be freestanding and able to be developed into any shape or size.

There is no doubt that more and more applications using CNT films could be developed as time goes on.  The CNT thin films can also be made into small area devices such as earphones and buzzers. This technique might open up new applications and approaches to manufacturing loudspeakers and other acoustic devices. If you’re a sounded instrument player just imagine it had a coating of CNT speakers on it that could enhance the sound of your instrument. The film can also be applied to the iPod, placed on window glass, or even over paintings to make transparent loudspeakers.

Previous research into self-healing materials has mostly focused on restoring mechanical properties after a damaging event. We already wrote about self-healing concrete and the University of Illinois researchers have already made self-healing coatings that can repair scratches and prevent corrosion on boats or car chassis. Now the group has brought the same techniques to the problem of restoring electronic properties.

“We want to address common failures in cell phones and other portable electronics,” says Paul Braun, a professor of materials science and engineering at the University of Illinois who leads the research project with Jeffrey Moore, a professor of chemistry, materials science, and engineering. These failures may become an even bigger problem as flexible electronics, which are subject to much more mechanical stress, become widespread, says Braun.

To make their self-healing material, Braun and Moore encapsulated carbon nanotubes inside polymer spheres about 200 micrometers in diameter each. They selected carbon nanotubes because of their high electrical conductivity and because their elongated shape does a good job of lining up to bridge gaps.

In their experiments (PDF), the researchers ripped the capsules apart and placed the resulting mixture between the tips of two electrical probes. The released nanotubes formed a bridge that completed the circuit between the two probes. Though the polymer itself isn’t conductive, there was a net positive increase in conductivity after it filled the rupture.

The researchers are currently developing ways to precisely position the spheres. Braun says the group has had a paper accepted describing the use of a technique called electrospraying to place the nanotube bubbles. The group is also working on more realistic tests for the capsules, including fracture studies in conductive materials.

With their further development, self-healing circuits could lead to lighter, cheaper and more efficient devices, particularly in critical, hard-to-repair situations. Currently, engineers build redundancy into such systems to guard against a total failure, but if the devices were able to heal themselves such redundancy systems wouldn’t be necessary. There is also potential for the technology to be used in batteries to restore the electrical conductivity of damaged battery electrodes, thereby preventing a short circuit that could lead to the battery exploding and also prolonging lifespans of rechargeable batteries.

The results of this research showed that E-Skin, originally made of organic transistors developed by combination of carbon nanotubes, fused in ionized liquid and polymers, has the ability of stretching 1.7 times of its original size without any loss of its conductivity or stretching up to 2.3 times of the original size when the conductivity drops roughly by half. The material can be placed over any rough surface without conductivity losses.

Practical uses of this super conductor are unlimited. One of the uses is in car industry on the surface of the steering wheels, where E-Skin could analyze perspiration, body temperature and other data of the driver in order to judge the drivers current condition in order to determine if the driver is capable for driving in that moment. It could be used as a protection against theft etc.

Tsuyoshi Sekitani, a research associate in the team, said:” It could be completely integrated into the normal driving system, making users unaware of using it”.

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If this special material would be implemented onto robots it would be able to give them a sense of touch even more advanced than ours. Someya and his colleagues are convinced that the functionality of E-Skin can be expanded so it would be able to incorporate additional types of sensors. In their words, in near future it will be possible to make electronic skin with functions that human skin lacks. The additional sensing would include sensors for temperature, pressure, light, humidity, strain and even the sensors for ultrasonic sound.

The new batteries could be manufactured with a cheap and environmentally friendly process: The synthesis takes place at and below room temperature and requires no harmful organic solvents, and the materials that go into the battery are non-toxic. Unlike traditional lithium-ion battery where lithium ions flow between a negatively charged anode (usually graphite) and the positively charged cathode (usually cobalt oxide or lithium iron phosphate) the viruses build an anode by coating themselves with cobalt oxide and gold and self-assembling to form a nanowire.

“In the latest work, the team focused on building a highly powerful cathode to pair up with the anode”, said Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering. “Cathodes are more difficult to build than anodes because they must be highly conducting to be a fast electrode, however, most candidate materials for cathodes are highly insulating (non-conductive).”

To achieve that, the researchers, including MIT Professor Gerbrand Ceder of materials science and Associate Professor Michael Strano of chemical engineering, genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material.

Each iron phosphate nanowire can be electrically “wired” to conducting carbon nanotube networks because the viruses recognize and bind specifically to certain materials (carbon nanotubes in this case). Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time.

The team found that incorporating carbon nanotubes increases the cathode’s conductivity without adding too much weight to the battery. In lab tests, batteries with the new cathode material could be charged and discharged at least 100 times without losing any capacitance. That is fewer charge cycles than currently available lithium-ion batteries, but the researchers expect them to be able to go much longer.

The prototype is packaged as a typical coin cell battery, but the technology allows for the assembly of very lightweight, flexible and conformable batteries that can take the shape of their container.

“Now that the researchers have demonstrated they can wire virus batteries at the nanoscale, they intend to pursue even better batteries using materials with higher voltage and capacitance, such as manganese phosphate and nickel phosphate”, said Belcher, “Once that next generation is ready, the technology could go into commercial production.”

This entirely new approach to nano-production does appear greener, and though there is some genetic engineering involved it doesn’t raise too much disagreement with the project development.

Thermodynamics, the crown jewel of 19th-century physics, concerns systems with many particles. Quantum mechanics, developed in the 20th century, works best when applied to just a few. The UCLA team is using their tiny light bulb to study Planck’s black-body radiation law, which was derived in 1900 using principles now understood to be native to both theories.

Planck’s law describes radiation from large, hot objects, such as the Sun or a light bulb. Some such radiation is of fundamental and current scientific interest; the thermal radiation left over from the Big Bang, for instance, which is called the cosmic microwave background, is described by Planck’s law.

Their tiny light bulb utilizes a filament made from a single carbon nanotube that is only 100 atoms wide. To the unaided eye, the filament is completely invisible when the lamp is off, but it appears as tiny point of light when the lamp is turned on. Even with the best optical microscope, it is only just possible to resolve the nanotube’s non-zero length. To image the filament’s true structure, the team uses an electron microscope capable of atomic resolution at the Electron Imaging Center for Nanomachines (EICN) core lab at CNSI.

With less than 20 million atoms, the nanotube filament is both large enough to apply the statistical assumptions of thermodynamics and small enough to be considered as a molecular — that is, quantum mechanical — system.

“Our goal is to understand how Planck’s law gets modified at small length scales,” Regan said. “Because both the topic (black-body radiation) and the size scale (nano) are on the boundary between the two theories, we think this is a very promising system to explore.”

The carbon nanotube makes an ideal filament for this experiment, since it has both the requisite smallness and the extraordinary temperature stability of carbon. While the intensive study of carbon nanotubes only began in 1991, using carbon in a light bulb is not a new idea. Thomas Edison’s original light bulbs used carbon filaments.

The UCLA research team’s light bulb is very similar to Edison’s, except that their filament is 100,000 times narrower and 10,000 times shorter, for a total volume only one one-hundred-trillionth that of Edison’s.

This breakthrough comes at a time when inventors are moving away from the usage of common light bulbs and even looking beyond the environmentally friendlier compact fluorescent bulbs (CFLs), and trying to figure out how to make LED lights cheap enough to take over the job of lighting homes and offices.

The invention is aiming to help the scientists in order to have a better understanding on the potential relation between the physics of large things and the physics of particles. If no lights went on for you there, be comforted by the thought that all this bears on the anticipated “theory of everything” which would, if discovered, help our understanding of gravity and how the universe works.

Graphene, an atom-thick sheet of honeycombed carbon, is one of the hottest materials around. It conducts electrons well, but is thin, transparent and strong, making it potentially useful in displays and solar panels. Ribbons of graphene could be more useful still. At widths of around 10 nanometers or less, electrons are forced to move lengthwise, and make the graphene behave as a semiconductor.

However, the ribbons have proved extremely difficult to produce. In previously used methods nanoribbons of graphene were cut from larger sheets using chemical methods that, like a blunt pair of scissors, offer little control over the width of the ribbons. In the two new studies the research groups found ways to unroll carbon nanotubes to produce nanoribbons.

One team, led by the Hongjie Dai from the Stanford University, is making graphene nanoribbons (GNRs) – materials with properties distinct from those of other carbon allotropes. The all-semi-conducting nature of GNRs could bypass the problem of the extreme chirality dependence of the metal or semiconductor nature of CNTs in future electronics. Currently, making GNRs using lithographic chemical or sonochemical methods is challenging. It is difficult to obtain GNRs with smooth edges and controllable widths at high yields. The making of GNRs is done by fixing nanotubes onto a polymer film and then using ionized argon gas to cut away a strip of each tube.

Once cleaned, the GNRs have smooth edges and a narrow width distribution (10–20nm). Raman spectroscopy and electrical transport measurements reveal the high quality of the GNRs. Unzipping CNTs with well-defined structures in an array will allow the production of GNRs with controlled widths, edge structures, placement and alignment in a scalable fashion for device integration.

The other team, led by the James Tour from the Rice University lab, has uncovered a room-temperature chemical process that splits CNTs in order to make flat nanoribbons. The technique makes it possible to produce the ultra thin ribbons in bulk quantities. These ribbons are straight-edged sheets of graphene, the single-layer form of common graphite found in pencils. You’d have to place thousands of them side by side to equal the width of a human hair, but tests show graphene is 200 times stronger than steel.

The process involves sulfuric acid and potassium permanganate. The chemical reacts with single and multi-walled carbon nanotubes and unzips them in a straight line. The unzipping action can start on the end or in the middle, but the result is the same – the tubes turn into flat, straight-edged, water-soluble ribbons of graphene. When produced in bulk, these microscopic sheets can be “painted” onto a surface or combined with a polymer to let it conduct electricity. The resulting ribbons are wider (around 100–500 nm) and aren’t semi-conducting, but are easier to make in large quantities.

Nearly all of the nanotubes subjected to unzipping turn into graphene ribbons, Tour said, and the basic process is the same for single or multi-walled tubes. Single-walled carbon nanotubes convert to sheets at room temperature and are good for small electronic devices because the width of the unzipped sheet is highly controllable. But the multi-walled nanotubes are much cheaper starting materials and the resulting nanoribbons would be useful in a host of applications.

The researchers say there are an enormous number of potential applications for nanoribbons. Tour’s larger ribbons could be used in touch-screen displays, flexible electronics, and solar panels, he says, noting that his nanoribbons are easy to process because they are graphene oxide, which is soluble in water. Dai’s thinner ribbons are more likely to be used in electronics due to their semi-conducting ability and smaller size. The researchers say that the methods are being licensed for commercial development.

There are many different techniques which are used to produce nanotubes in sizeable quantities. Among most accepted are arc discharge, laser ablation, high pressure carbon monoxide (HiPCO), and chemical vapor deposition (CVD). Most of these processes take place in vacuum or with process gases. CVD growth of carbon naotubes can occur in vacuum or at atmospheric pressure. Advances in catalysis and continuous growth processes are making carbon nanotubes more commercially viable.

Carbon nanotubes (CNTs) are allotropes of carbon with a nanostructure that can have a length-to-diameter ratio of up to 28,000,000:1, which is considerably larger than any other material. These cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science, as well as potential uses in architectural fields. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Their final usage, however, may be limited by their potential toxicity.

A study named “Direct imaging of single-walled carbon nanotubes in cells” led by Alexandra Porter from the University of Cambridge shows that CNTs can enter human cells and accumulate in the cytoplasm, causing cell death.

A group of other studies collectively show that regardless of the process by which CNTs were synthesized and the types and amounts of metals they contained, CNTs were capable of producing inflammation, microscopic nodules, fibrosis, and biochemical/toxicological changes in the lungs.

The needle-like fiber shape of CNTs, similar to asbestos fibers, raises fears that widespread use of carbon nanotubes may lead to cancer of the lining of the lungs often caused by exposure to asbestos.

Despite those facts researchers invest a lot of their resources into the development of technologies which rely on nanotubes. The technology is used in many applications such as nanotechnology, electronics, optics and other fields of materials science, as well as potential uses in architectural fields.

Multi-walled nanotubes (MWNT) consist of concentric tubes of graphite. There are two models which can be used to describe the structures of multi-walled nanotubes – the Russian Doll model and the Parchment model. In the Russian Doll model, sheets of graphite are arranged in concentric cylinders while in the Parchment model, a single sheet of graphite is rolled in around itself, like a scroll of parchment or a rolled newspaper.

The double-walled carbon nanotubes (DWNT) are widely used because of their morphology and properties. DWNTs are similar to SWNT but their resistance to chemicals is significantly improved. This is especially important when chemical functions are added to the surface of the nanotubes thus adding new properties to the CNT.

A nanotorus is a theoretically described carbon nanotube bent into a torus. Nanotori are predicted to have many unique properties, such as magnetic moments 1000 times larger than previously expected.

Carbon nanobuds are a newly created material combining two previously discovered allotropes of carbon; carbon nanotubes and fullerenes. In composite materials, the attached fullerene molecules may function as molecular anchors or bonds. By this means, carbon nanobds could be used to prevent the slipping of the nanotubes or to connect them as in a manner similar to building blocks. thus improving the composite’s mechanical properties.

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The strength and flexibility of carbon nanotubes makes them of potential use in controlling other nanoscale structures, which suggests they will have an important role in nanotechnology engineering.

Comparing to other contemporary technologies which are close to their permeation, nanotubes are still relatively expensive to produce. However, the market of nanotubes keeps on growing and the prices are more acceptable.

Many applications of this technology are going to be reviewed in our future articles.