Thin Films Power Electronics Mixed In Fabrics

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) reported significant advances in the thermoelectric performance of organic semiconductors based on carbon nanotube thin films that could be integrated into fabrics to convert waste heat into electricity or serve as a small power source.

The research demonstrates significant potential for semiconducting single-walled carbon nanotubes (SWCNTs) as the primary material for efficient thermoelectric generators, rather than being used as a component in a “compositethermoelectric material containing, for example, carbon nanotubes and a polymer. The discovery is outlined in the new Energy & Environmental Science paper, Large n- and p-type thermoelectric power factors from doped semiconducting single-walled carbon nanotube thin films.

There are some inherent advantages to doing things this way,” said Jeffrey Blackburn, a senior scientist in NREL’s Chemical and Materials Science and Technology center and co-lead author of the paper with Andrew Ferguson. These advantages include the promise of solution-processed semiconductors that are lightweight and flexible and inexpensive to manufacture. Other NREL authors are Bradley MacLeod, Rachelle Ihly, Zbyslaw Owczarczyk, and Katherine Hurst. The NREL authors also teamed with collaborators from the University of Denver and partners at International Thermodyne, Inc., based in Charlotte, N.C.

Ferguson, also a senior scientist in the Chemical and Materials Science and Technology center, said the introduction of SWCNT into fabrics could serve an important function for “wearable” personal electronics. By capturing body heat and converting it into electricity, the semiconductor could power portable electronics or sensors embedded in clothing.

Source: https://www.nrel.gov/

Rechargeable Lithium Metal Battery

Rice University scientists have created a rechargeable lithium metal battery with three times the capacity of commercial lithium-ion batteries by resolving something that has long stumped researchers: the dendrite problem.

The Rice battery stores lithium in a unique anode, a seamless hybrid of graphene and carbon nanotubes. The material first created at Rice in 2012 is essentially a three-dimensional carbon surface that provides abundant area for lithium to inhabit. Lithium metal coats the hybrid graphene and carbon nanotube anode in a battery created at Rice University. The lithium metal coats the three-dimensional structure of the anode and avoids forming dendrites.

The anode itself approaches the theoretical maximum for storage of lithium metal while resisting the formation of damaging dendrites or “mossy” deposits.

Dendrites have bedeviled attempts to replace lithium-ion with advanced lithium metal batteries that last longer and charge faster. Dendrites are lithium deposits that grow into the battery’s electrolyte. If they bridge the anode and cathode and create a short circuit, the battery may fail, catch fire or even explode.

Rice researchers led by chemist James Tour found that when the new batteries are charged, lithium metal evenly coats the highly conductive carbon hybrid in which nanotubes are covalently bonded to the graphene surface. As reported in the American Chemical Society journal ACS Nano, the hybrid replaces graphite anodes in common lithium-ion batteries that trade capacity for safety.

Lithium-ion batteries have changed the world, no doubt,” Tour said, “but they’re about as good as they’re going to get. Your cellphone’s battery won’t last any longer until new technology comes along.

He said the new anode’s nanotube forest, with its low density and high surface area, has plenty of space for lithium particles to slip in and out as the battery charges and discharges. The lithium is evenly distributed, spreading out the current carried by ions in the electrolyte and suppressing the growth of dendrites.

Source: http://news.rice.edu

How To Detect Nuclear Device

How to keep U.S. ports of entry safe and secure by detecting and interdicting illicit radioactive or nuclear materials? A team led by Northeastern’s Swastik Kar and Yung Joon Jung has developed a technology that could go a long way toward achieving that goal.

nuclear radiation

Our detector could dramatically change the manner and accuracy with which we are able to detect nuclear threats at home or abroad,” says Kar, associate professor in the Department of Physics. It could also help streamline radio-medicine, including radiation therapies and scanning diagnostics, boost the effectiveness of unmanned radiation monitoring vehicles in mapping and monitoring contaminated areas following disasters, and revolutionize radiometric imaging in space exploration. Made of graphene and carbon nanotubes, the researchers’ detector far outpaces any existing one in its ultrasensitivity to charged particles, minuscule size, low-power requirements, and low cost.

All radiation, of course, is not harmful, and even the type that may be depends on dosage and length of exposure. The word “radiation” refers simply to the emission and propagation of energy in the form of waves or particles. It has many sources, including the sun, electronic devices such as microwaves and cellphones, visible light, X-rays, gamma waves, cosmic waves, and nuclear fission, which is what produces power in nuclear reactors. Most of the harmful radiations are “ionizing radiations”—they have sufficient energy to remove electrons from the orbits of surrounding atoms, causing them to become charged, or “ionized.” It is those charged particles, or ions, that the detectors pick up and quantify, revealing the intensity of the radiation. Most current detectors, however, are not only bulky, power hungry, and expensive, they also cannot pick up very low levels of ions. Kar and Yung Joon’s detector, on the other hand, is so sensitive it can pick up just a single charged particle.

Our detectors are many orders of magnitude more sensitive in terms of how small a signal they can detect,” says Yung Joon, associate professor in the Department of Mechanical and Industrial Engineering. “Ours can detect one ion, the fundamental limit. If you can detect a single ion, then you can detect everything larger than that.”

Source: http://news.northeastern.edu/

How To Track Stem Cells In The Body

Rice University researchers have synthesized a new and greatly improved generation of contrast agents for tagging and real-time tracking of stem cells in the body. The agent combines ultrashort carbon nanotubes and bismuth clusters that show up on X-rays taken with computed tomography (CT) scanners. The stable compound performs more than eight times better than the first-generation material introduced in 2013, according to the researchers.

XRAY
An improved compound of bismuth and carbon nanotubes called Bi4C@US-tubes, developed at Rice University could enhance the ability to track stem cells as they move through the body and target diseases

The primary application will be to track them in stem-cell therapies to see if the cells are attracted to the site of disease — for example, cancer — and in what concentration,” said Rice chemist Lon Wilson of the compound the researchers call Bi4C@US-tubes.

Magnetic resonance imaging is currently used for that purpose and it works quite well, but X-ray technology in the clinic is much more available,” he said. “It’s faster and cheaper, and it could facilitate preclinical studies to track stem cells in vivo.”

Bismuth is used in cosmetics, pigments and pharmaceuticals, notably as the active ingredient in pink bismuth (aka Pepto-Bismol), an antacid. For this application, bismuth nanoclusters developed by the lab of Rice chemist Kenton Whitmire, a co-author of the paper, are combined with carbon nanotubes chemically treated to shorten them to between 20 and 80 nanometers and add defects to their side walls. The nanoclusters, which make up about 20 percent of the compound, appear to strongly attach to the nanotubes via these defects.

When introduced into stem cells, the treated nanotubes become easy to spot, Wilson said. “It’s very interesting to see a cell culture that is opaque to X-rays. They’re not as dark as bone (which X-rays cannot penetrate), but they’re really dark when they’re loaded with these agents.”

The process developed by Wilson’s team and colleagues at CHI St. Luke’s Health-Baylor St. Luke’s Medical Center and Baylor College of Medicine is detailed this month in the American Chemical Society journal ACS Applied Materials and Interfaces.

Source: http://news.rice.edu/

Smart Textile Senses And Moves Like A Muscle

The ARC Center of Excellence for Electromaterials Science (ACES – Australia) researchers have for the first time, developed a smart textile from carbon nanotube and spandex fibres that can both sense and move in response to a stimulus like a muscle or joint.

Lead researcher Dr Javad Foroughi explains that the key difference between this, and previous ACES work, is the textile’s dual functionality.

katharina_schirmer_graduates

We have already made intelligent materials as sensors and integrated them into devices such as a knee sleeve that can be used to monitor the movement of the joint, providing valuable data that can be used to create a personalised training or rehabilitation program for the wearer,” Dr Foroughi said. “Our recent work allowed us to develop smart clothing that simultaneously monitors the wearer’s movements, senses strain, and adjusts the garment to support or correct the movement,” he adds.

The smart textile, which is easily scalable for the fabrication of industrial quantities, generates a mechanical work capacity and a power output which higher than that produced by human muscles. It has many potential applications ranging from smart textiles to robotics and sensors for lab on a chip devices. The team, having already created the knee sleeve prototype, is now working on using the smart textile as a wearable antenna, as well as in other biomedical applications.

Source: http://www.electromaterials.edu.au/

Molecular Electronics

Technion researchers in Israel  have developed a method for growing carbon nanotubes that could lead to the day when molecular electronics replace the ubiquitous silicon chip as the building block of electronicsCarbon nanotubes (CNTs) have long fascinated scientists because of their unprecedented electrical, optical, thermal and mechanical properties, and chemical sensitivity. But significant challenges remain before CNTs can be implemented on a wide scale, including the need to produce them in specific locations on a smooth substrate, in conditions that will lead to the formation of a circuit around them.

Led by Prof. Yuval Yaish of the Viterbi Faculty of Electrical Engineering and the Zisapel Nanoelectronics Center at the Technion, the researchers have developed a technology that addresses these challenges. Their breakthrough also makes it possible to study the dynamic properties of CNTs, including acceleration, resonance (vibration), and the transition from softness to hardness. The method could serve as an applicable platform for the integration of nano-electronics with silicon technologies, and possibly even the replacement of these technologies in molecular electronics.

Carbon naotube

Due to the nanometer size of the CNTs (100,000 times smaller in diameter than the thickness of a human hair) it is extremely difficult to find or locate them at specific locations. Prof. Yaish, and graduate students Gilad Zeevi and Michael Shlafman, developed a simple, rapid, non-invasive and scalable technique that enables optical imaging of CNTs.

 

The CNT is an amazing and very strong building block with remarkable electrical, mechanical and optical properties,” said Prof. Yaish. “Some are conductors, and some are semiconductors, which is why they are considered a future replacement for silicon. But current methods for the production of CNTs are slow, costly, and imprecise. As such, they generally cannot be implemented in industry.”

Our approach is the opposite of the norm,” he continued. “We grow the CNTs directly, and with the aid of the organic crystals that coat them, we can see them under a microscope very quickly. Then image identification software finds and produces the device (transistor). This is the strategy. The goal is to integrate CNTs in an integrated circuit of miniaturized electronic components (mainly transistors) on a single chip (VLSI). These could one day serve as a replacement for silicon electronics.”

The findings have been published in Nature Communications.

Source: http://www.ats.org/

How To Remove All Nanomaterials From Water

Nano implies small—and that’s great for use in medical devices, beauty products and smartphones—but it’s also a problem. The tiny nanoparticles, nanowires, nanotubes and other nanomaterials that make up our technology eventually find their way into water. The Environmental Protection Agency says more 1,300 commercial products use some kind of nanomaterial. And we just don’t know the full impact on health and the environment.

Michigan Technological

Look at plastic,” says Yoke Khin Yap, a professor of physics at Michigan Technological University. “These materials changed the world over the past decades—but can we clean up all the plastic in the ocean? We struggle to clean up meter-scale plastics, so what happens when we need to clean on the nano-scale?”

That challenge is the focus of a new study co-authored by Yap, recently published in the American Chemical Society’s journal Applied Materials and Interfaces. Yap and his team found a novel—and very simple—way to remove nearly 100 percent of nanomaterials from water.

Source: http://www.mtu.edu/

Nanotube-based Transistor For Nanocomputers

Individual transistors made from carbon nanotubes are faster and more energy efficient than those made from other materials. Going from a single transistor to an integrated circuit full of transistors, however, is a giant leap.

carbon nanotube integrated circuits

A single microprocessor has a billion transistors in it,” said Northwestern Engineering’s Mark Hersam. “All billion of them work. And not only do they work, but they work reliably for years or even decades.

When trying to make the leap from an individual, nanotube-based transistor to wafer-scale integrated circuits, many research teams, including Hersam’s, have met challenges. For one, the process is incredibly expensive, often requiring billion-dollar cleanrooms to keep the delicate nano-sized components safe from the potentially damaging effects of air, water, and dust. Researchers have also struggled to create a carbon nanotube-based integrated circuit in which the transistors are spatially uniform across the material, which is needed for the overall system to work.

Now Hersam and his team have found a key to solving all these issues. The secret lies in newly developed encapsulation layers that protect carbon nanotubes from environmental degradation.

Supported by the Office of Naval Research and the National Science Foundation, the research appears online in Nature Nanotechology on September 7. Tobin J. Marks,  professor of materials science and engineering in the McCormick School of Engineering, coauthored the paper. Michael Geier, a graduate student in Hersam’s lab, was first author. “One of the realities of a nanomaterial, such as a carbon nanotube, is that essentially all of its atoms are on the surface,” said Hersam, the Walter P. Murphy Professor of Materials Science and Engineering. “So anything that touches the surface of these materials can influence their properties. If we made a series of transistors and left them out in the air, water and oxygen would stick to the surface of the nanotubes, degrading them over time. We thought that adding a protective encapsulation layer could arrest this degradation process to achieve substantially longer lifetimes.

Hersam compares his solution to one currently used for organic light-emitting diodes (LEDs), which experienced similar problems after they were first realized. Many people assumed that organic LEDs would have no future because they degraded in air. After researchers developed an encapsulation layer for the material, organic LEDs are now used in many commercial applications, including displays for smartphones, car radios, televisions, and digital cameras. Made from polymers and inorganic oxides, Hersam’s encapsulation layer is based on the same idea but tailored for carbon nanotubes.

To demonstrate proof of concept, Hersam developed nanotube-based static random-access memory (SRAM) circuits. SRAM is a key component of all microprocessors, often making up as much as 85 percent of the transistors in the central-processing unit in a common computer. To create the encapsulated carbon nanotubes, the team first deposited the carbon nanotubes from a solution previously developed in Hersam’s lab. Then they coated the tubes with their encapsulation layers.

Using the encapsulated carbon nanotubes, Hersam’s team successfully designed and fabricated arrays of working SRAM circuits. Not only did the encapsulation layers protect the sensitive device from the environment, but they improved spatial uniformity among individual transistors across the wafer. While Hersam’s integrated circuits demonstrated a long lifetime, transistors that were deposited from the same solution but not coated degraded within hours.

After we’ve made the devices, we can leave them out in air with no further precautions,” Hersam said. “We don’t need to put them in a vacuum chamber or controlled environment. Other researchers have made similar devices but immediately had to put them in a vacuum chamber or inert environment to keep them stable. That’s obviously not going to work in a real-world situation.”

Source: http://www.mccormick.northwestern.edu/

A Billion Holes Make a Postage Stamp Battery

Researchers at the University of Maryland (UMD) have invented a single tiny structure that includes all the components of a battery that they say could bring about the ultimate miniaturization of energy storage components.
nanopores
A billion nanopores could fit on a postage stamp
The structure is called a nanopore: a tiny hole in a ceramic sheet that holds electrolyte to carry the electrical charge between nanotube electrodes at either end. The existing device is a test, but the bitsy battery performs well. First author Chanyuan Liu, a Ph.D. student in materials science, says that it can be fully charged in 12 minutes, and it can be recharged thousands of time.

Many millions of these nanopores can be crammed into one larger battery the size of a postage stamp. One of the reasons the researchers think this unit is so successful is because each nanopore is shaped just like the others, which allows them to pack the tiny thin batteries together efficiently.The space inside the holes is so small that the space they take up, all added together, would be no more than a grain of sand.
Now that the scientists have the battery working and have demonstrated the concept, they have also identified improvements that could make the next version 10 times more powerful. The next step to commercialization: the inventors have conceived strategies for manufacturing the battery in large batches.

A team of UMD chemists and materials scientists collaborated on the project: Gary Rubloff, director of the Maryland NanoCenter, Sang Bok Lee, a professor in the Department of Chemistry and seven of their Ph.D. students.
Source: http://www.umdrightnow.umd.edu/

Electric Car: How To Produce Cheap Hydrogen

Rutgers University researchers have developed a technology that could overcome a major cost barrier to make clean-burning hydrogen fuel – a fuel that could replace expensive and environmentally harmful fossil fuels.

The new technology is a novel catalyst that performs almost as well as cost-prohibitive platinum for so-called electrolysis reactions, which use electric currents to split water molecules into hydrogen and oxygen. The Rutgers technology is also far more efficient than less-expensive catalysts investigated to-date.
Hydrogen has long been expected to play a vital role in our future energy landscapes by mitigating, if not completely eliminating, our reliance on fossil fuels,” said Tewodros (Teddy) Asefa, associate professor of chemistry and chemical biology in the School of Arts and Sciences. “We have developed a sustainable chemical catalyst that, we hope with the right industry partner, can bring this vision to life”. He and his colleagues based their new catalyst on carbon nanotubesone-atom-thick sheets of carbon rolled into tubes 10,000 times thinner than a human hair.
carbon nanotubes to produce hydrogen

A new technology based on carbon nanotubes promises commercially viable hydrogen production from water

Finding ways to make electrolysis reactions commercially viable is important because processes that make hydrogen today start with methane – itself a fossil fuel. The need to consume fossil fuel therefore negates current claims that hydrogen is a “green” fuel.
Source: http://news.rutgers.edu

Graphene, Perfect Candidate For Solar Cells Efficiency

Dr. Marc Gluba and Prof. Dr. Norbert Nickel of the HZB Institute for Silicon Photovoltaics – Berlin, Germany – have shown that graphene retains its impressive set of properties when it is coated with a thin silicon film. These findings have paved the way for entirely new possibilities to use in thin-film photovoltaics. Graphene has extreme conductivity and is completely transparent while being inexpensive and nontoxic. This makes it a perfect candidate material for transparent contact layers for use in solar cells to conduct electricity without reducing the amount of incoming light – at least in theory. Whether or not this holds true in a real world setting is questionable as there is no such thing as “idealgraphene – a free floating, flat honeycomb structure consisting of a single layer of carbon atoms: interactions with adjacent layers can change graphene’s properties dramatically.

solarPanelWe examined how graphene’s conductive properties change if it is incorporated into a stack of layers similar to a silicon based thin film solar cell and were surprised to find that these properties actually change very little,” Marc Gluba explains.”That’s something we didn’t expect to find, but our results demonstrate that graphene remains graphene even if it is coated with silicon,”, says Norbert Nickel.

Source: http://www.helmholtz-berlin.de/

How To Develop Stronger Artificial Hearts

Ali Khademhosseini,, a researcher from the Brigham and Women’s Hospital, a division of Harvard Medical School, has created ultra-thin cardiac patches. Now medicine is a step closer to durable, high-functioning artificial tissues that could be used to repair damaged hearts and other organs.

artificial-heart
The cardiac tissue patches utilize a hydrogel scaffolding reinforced by nanomaterials called carbon nanotubes. To create the patches, the researchers seeded neonatal rat heart muscle tissue onto carbon nanotube-infused hydrogels.
Source: http://researchfaculty.brighamandwomens.org/
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