Carbon Nanotubes Self-Assemble Into Tiny Transistors

Carbon nanotubes can be used to make very small electronic devices, but they are difficult to handle. University of Groningen (Netherlands) scientists, together with colleagues from the University of Wuppertal and IBM Zurich, have developed a method to select semiconducting nanotubes from a solution and make them self-assemble on a circuit of gold electrodes. The results look deceptively simple: a self-assembled transistor with nearly 100 percent purity and very high electron mobility. But it took ten years to get there. University of Groningen Professor of Photophysics and Optoelectronics Maria Antonietta Loi designed polymers which wrap themselves around specific carbon nanotubes in a solution of mixed tubes. Thiol side chains on the polymer bind the tubes to the gold electrodes, creating the resultant transistor.

polymer wrapped nanotube

In our previous work, we learned a lot about how polymers attach to specific carbon nanotubes, Loi explains. These nanotubes can be depicted as a rolled sheet of graphene, the two-dimensional form of carbon. ‘Depending on the way the sheets are rolled up, they have properties ranging from semiconductor to semi-metallic to metallic.’ Only the semiconductor tubes can be used to fabricate transistors, but the production process always results in a mixture.

We had the idea of using polymers with thiol side chains some time ago‘, says Loi. The idea was that as sulphur binds to metals, it will direct polymer-wrapped nanotubes towards gold electrodes. While Loi was working on the problem, IBM even patented the concept. ‘But there was a big problem in the IBM work: the polymers with thiols also attached to metallic nanotubes and included them in the transistors, which ruined them.’

Loi’s solution was to reduce the thiol content of the polymers, with the assistance of polymer chemists from the University of Wuppertal. ‘What we have now shown is that this concept of bottom-up assembly works: by using polymers with a low concentration of thiols, we can selectively bring semiconducting nanotubes from a solution onto a circuit.’ The sulphur-gold bond is strong, so the nanotubes are firmly fixed: enough even to stay there after sonication of the transistor in organic solvents.

Over the last years, we have created a library of polymers that select semiconducting nanotubes and developed a better understanding of how the structure and composition of the polymers influences which carbon nanotubes they select’, says Loi. The result is a cheap and scalable production method for nanotube electronics. So what is the future for this technology? Loi: ‘It is difficult to predict whether the industry will develop this idea, but we are working on improvements, and this will eventually bring the idea closer to the market.’

The results were published in the journal Advanced Materials on 5 April.
Source: http://www.rug.nl/
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Semiconductors As Thin As An Atom

A two-dimensional material developed by physicist Prof. Dr. Axel Enders (Bayreuth University  in Germany) together with international partners could revolutionize electronicsSemiconductors that are as thin as an atom are no longer the stuff of .  Thanks to its semiconductor properties, this material could be much better suited for high tech applications than graphene, the discovery of which in 2004 was celebrated worldwide as a . This new material contains carbon, boron, and nitrogen, and its chemical name is “Hexagonal Boron-Carbon-Nitrogen (h-BCN)”. The new development was published in the journal ACS Nano.

2D material Bayreuth University

Our findings could be the starting point for a new generation of electronic transistors, circuits, and sensors that are much smaller and more bendable than the electronic elements used to date. They are likely to enable a considerable decrease in power consumption,” Prof. Enders predicts, citing the CMOS technology that currently dominates the electronics industry. This technology has clear limits with regard to further miniaturization. “h-BCN is much better suited than graphene when it comes to pushing these limits,” according to Enders.

Graphene is a two-dimensional lattice made up entirely of carbon atoms. It is thus just as thin as a single atom. Once scientists began investigating these structures more closely, their remarkable properties were greeted with enthusiasm across the world. Graphene is 100 to 300 times stronger than steel and is, at the same time, an excellent conductor of heat and electricity.

Source: https://www.uni-bayreuth.de/

Nano Printing Heralds NanoComputers Era

A new technique using liquid metals to create integrated circuits that are just atoms thick could lead to the next big advance for electronics. The process opens the way for the production of large wafers around 1.5 nanometres in depth (a sheet of paper, by comparison, is 100,000nm thick). Other techniques have proven unreliable in terms of quality, difficult to scale up and function only at very high temperatures – 550 degrees or more.

Professor Kourosh Kalantar-zadeh, from RMIT’s School of Engineering in Australia , led the project with  colleagues from RMIT and researchers from CSIRO, Monash University, North Carolina State University and the the University of California, He observed that the electronics industry had “hit a barrier.

nano printing

The fundamental technology of car engines has not progressed since 1920 and now the same is happening to electronics. Mobile phones and computers are no more powerful than five years ago. That is why this new 2D printing technique is so important – creating many layers of incredibly thin electronic chips on the same surface dramatically increases processing power and reduces costsIt will allow for the next revolution in electronics.

Benjamin Carey, a researcher with RMIT and the CSIRO, said creating electronic wafers just atoms thick could overcome the limitations of current chip production. It could also produce materials that were extremely bendable, paving the way for flexible electronics. “However, none of the current technologies are able to create homogenous surfaces of atomically thin semiconductors on large surface areas that are useful for the industrial scale fabrication of chips.  Our solution is to use the metals gallium and indium, which have a low melting point.  These metals produce an atomically thin layer of oxide on their surface that naturally protects them. It is this thin oxide which we use in our fabrication method,”  explains Carey.

By rolling the liquid metal, the oxide layer can be transferred on to an electronic wafer, which is then sulphurised. The surface of the wafer can be pre-treated to form individual transistors.  We have used this novel method to create transistors and photo-detectors of very high gain and very high fabrication reliability in large scale,” he adds.

The paper outlining the new technique has been published in the journal Nature Communications.

Source: http://www.rmit.edu.au/

A ”NaNose” Device Identifies 17 Types Of Diseases With A Single Sniff

The future of early diagnoses of disease could be this simple, according to a team of researchers in Israel. The ‘NaNose‘ as they call it can differentiate between 17 types of diseases with a single sniff identifying so-called smelly compounds in anything from cancers to Parkinson’s.

nanose2CLICK ON THE IMAGE TO ENJOY THE VIDEO

Indeed, what we have found in our most recent research in this regard, that 17 types of disease have 13 common compounds that are found in all different types of disease, but the mixture of the compounds and the composition of these compounds changes from one disease to another disease. And this is what is really unique and what really we expect to see and utilize in order to make the diagnosis from exhaled breat,” says Professor Hossam  Haick ftom the Institute of Technology- Technion.

The NaNose uses “artificially intelligent nanoarraysensors to analyze the data obtained from receptors that “smell” the patient’s breath.

So our main idea is to try an imitate what’s going on in nature. So like we can take a canine, a dog and train it to scent the smell of drugs, of explosives or a missing person, we are trying to do it artificially. And we can do that by using these nano-materials and we build these nano material-based sensors. And of course there are many advantages and one of them of course is going all the way from sensors big as this to really small devices like this that have that have on them eight sensors and which can be incorporated to systems like this, or even smaller,” explains Doctor Yoav Broza from Technion .

Several companies are now trying to commercialize the technology – and encourage its use in healthcare systems… or see it incorporated into your smartphone.

Source: http://www.reuters.com/

Printing With Nanomaterials

Researchers at Binghamton University are focusing on printed electronics: using inkjet technology to print electronic nanomaterials onto flexible substrates. When compared to traditional methods used in microelectronics fabrication, the new technology conserves material and is more environmentally friendly.

Think of inkjet printing and you’ll likely picture an old printer in an office. Not so if you’re Timothy Singler, director of graduate studies and professor of mechanical engineering at Binghamton University. In the Transport Sciences Core at the Innovative Technologies Complex, Singler is collaborating with Paul Chiarot and Frank Yong, assistant professors of mechanical engineering, to study inkjet printing of functional materials.

Functional materials are categorized in terms of the actions they can perform rather than on the basis of their origins. Solution-processed materials may have electrical, optical, chemical, magnetic, thermal or other functionalities. For example, silver is strongly electrically conductive and can be formulated into nanoparticle ink. However, Singler explains that printing with solution-processed nanomaterials instead of traditional inks is significantly more complex.

3D printing “One really has to study how nanomaterials deposit on a substrate — what structures they form, how you can control them — because you’re dispersing the nanomaterials into a liquid so you can print them, and that liquid volatilizes, leaving only the material on the substrate. But the evaporation process and capillarity cause very complex flows that transport the material you’re trying to deposit in nonintuitive ways,” Singler says. “These flows have to be controlled to achieve an optimal functional structure at the end.”

Source: http://www.binghamton.edu/

Nanoelectronics Injected Directly Into The Brain

It’s a notion that might have come from the pages of a science-fiction novel — an electronic device that can be injected directly into the brain, or other body parts, and treat everything from neurodegenerative disorders to paralysis.

Led by Charles Lieber, Professor of Chemistry at Harvard University,  an international team of researchers has developed a method of fabricating nanoscale electronic scaffolds that can be injected via syringe. The scaffolds can then be connected to devices and used to monitor neural activity, stimulate tissues, or even promote regeneration of neurons.

brain synaptic symphonyI do feel that this has the potential to be revolutionary,” Lieber said. “This opens up a completely new frontier where we can explore the interface between electronic structures and biology. For the past 30 years, people have made incremental improvements in micro-fabrication techniques that have allowed us to make rigid probes smaller and smaller, but no one has addressed this issue — the electronics/cellular interface — at the level at which biology works.”

In an earlier study, scientists in Lieber’s lab demonstrated that cardiac or nerve cells grown with embedded scaffolds could be used to create “cyborgtissue. Researchers were then able to record electrical signals generated by the tissue, and to measure changes in those signals as they administered cardio– or neuro-stimulating drugs.

We were able to demonstrate that we could make this scaffold and culture cells within it, but we didn’t really have an idea how to insert that into pre-existing tissue,” Lieber said. “But if you want to study the brain or develop the tools to explore the brain-machine interface, you need to stick something into the body. When releasing the electronic scaffold completely from the fabrication substrate, we noticed that it was almost invisible and very flexible, like a polymer, and could literally be sucked into a glass needle or pipette. From there, we simply asked, ‘Would it be possible to deliver the mesh electronics by syringe needle injection?’

Though not the first attempt at implanting electronics into the braindeep brain stimulation has been used to treat a variety of disorders for decades — the nanofabricated scaffolds operate on a completely different scale.

Existing techniques are crude relative to the way the brain is wired,” Lieber said. “Whether it’s a silicon probe or flexible polymers … they cause inflammation in the tissue that requires periodically changing the position or the stimulation. But with our injectable electronics, it’s as if it’s not there at all. They are one million times more flexible than any state-of-the-art flexible electronics and have subcellular feature sizes. They’re what I call ‘neuro-philic’ — they actually like to interact with neurons.

The research is reported in Nature Nanotechnology.

Source: http://news.harvard.edu/

Nano Light Consumes Hundred Times Less Than A LED

Scientists from Tohoku University in Japan have developed a new type of energy-efficient flat light source based on carbon nanotubes with very low power consumption of around 0.1 Watt for every hour‘s operation — about a hundred times lower than that of an LED. Electronics based on carbon, especially carbon nanotubes (CNTs), are emerging as successors to silicon for making semiconductor materials, And they may enable a new generation of brighter, low-power, low-cost lighting devices that could challenge the dominance of light-emitting diodes (LEDs) in the future and help meet society’s ever-escalating demand for greener bulbs.
nanolightPlane-lighting homogeneity image of a planar light source device through a neutral density filter
Our simple ‘diode’ panel could obtain high brightness efficiency of 60 Lumen per Watt, which holds excellent potential for a lighting device with low power consumption,” said Norihiro Shimoi, the lead researcher and an associate professor of environmental studies at the Tohoku University. “We have found that a cathode with highly crystalline single-walled carbon nanotubes and an anode with the improved phosphor screen in our diode structure obtained no flicker field emission current and good brightness homogeneity,” Shimoi said.
Source: http://www.aip.org/

Electronics Enter The Nanocomputer Age

An UAlberta research team is developing atom-scale, ultra-low-power computing devices to replace transistor circuits. In the drive to get small, Robert Wolkow and his lab at the University of Alberta are taking giant steps forward. The digital age has resulted in a succession of smaller, cleaner and less power-hungry technologies since the days the personal computer fit atop a desk, replacing mainframe models that once filled entire rooms. Desktop PCs have since given way to smaller and smaller laptops, smartphones and devices that most of us carry around in our pockets. But as Wolkow points out, this technological shrinkage can only go so far when using traditional transistor-based integrated circuits. That’s why he and his research team are aiming to build entirely new technologies at the atomic scale.
Our ultimate goal is to make ultra-low-power electronics because that’s what is most demanded by the world right now,” said Wolkow, the iCORE Chair in Nanoscale Information and Communications Technology in the Faculty of Science. “We are approaching some fundamental limits that will stop the 30-year-long drive to make things faster, cheaper, better and smaller; this will come to an end soon. “An entirely new method of computing will be necessary.”

Wolkow and his team in the U of A’s physics department and the National Institute for Nanotechnology are working to engineer atomically precise technologies that have practical, real-world applications. His lab already made its way into the Guinness Book of World Records for inventing the world’s sharpest object—a microscope tip just one atom wide at its end.

Source: http://uofa.ualberta.ca/

Circuit Board Modeled On The Human Brain

Stanford bioengineers have developed faster, more energy-efficient microchips based on the human brain 9,000 times faster and using significantly less power than a typical PC. This offers greater possibilities for advances in robotics and a new way of understanding the brain. For instance, a chip as fast and efficient as the human brain could drive prosthetic limbs with the speed and complexity of our own actions. The new circuit board modeled on the human brain, is possibly opening up new frontiers in computing. For all their sophistication, computers pale in comparison to the brain. The modest cortex of the mouse, for instance, operates 9,000 times faster than a personal computer simulation of its functions. Not only is the PC slower, it takes 40,000 times more power to run, writes Kwabena Boahen, associate professor of bioengineering at Stanford, in an article for the Proceedings of the IEEE.

The Neurogrid circuit board can simulate orders of magnitude more neurons and synapses than other brain mimics on the power it takes to run a tablet computer

From a pure energy perspective, the brain is hard to match,” says Boahen, whose article surveys how “neuromorphic” researchers in the United States and Europe are using silicon and software to build electronic systems that mimic neurons and synapses.

Source: http://news.stanford.edu/

New High Capacity Flexible Battery

A Rice University laboratory has flexible, portable and wearable electronics in its sights with the creation of a thin film for energy storage. Rice chemist James Tour and his colleagues have developed a flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte to deliver battery-like supercapacitor performance that combines the best qualities of a high-energy battery and a high-powered supercapacitor without the lithium found in commercial batteries today.
Their electrochemical capacitor is about a hundredth of an inch thick but can be scaled up for devices either by increasing the size or adding layers, said Rice postdoctoral researcher Yang Yang, co-lead author of the paper with graduate student Gedeng Ruan. They expect that standard manufacturing techniques may allow the battery to be even thinner. In tests, the students found their square-inch device held 76 percent of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles. Tour said the team set out to find a material that has the flexible qualities of graphene, carbon nanotubes and conducting polymers while possessing much higher electrical storage capacity typically found in inorganic metal compounds. Inorganic compounds have, until recently, lacked flexibility, he said.


This is not easy to do, because materials with such high capacity are usually brittle,” he said. “And we’ve had really good, flexible carbon storage systems in the past, but carbon as a material has never hit the theoretical value that can be found in inorganic systems, and nickel fluoride in particular.”

Compared with a lithium-ion device, the structure is quite simple and safe,” Yang said. “It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.
The new work by the Rice lab of chemist James Tour is detailed in the Journal of the American Chemical Society.

Source: http://news.rice.edu/

Implanted Nano Cyborgs For Monitoring Your Health

The debut of cyborgs who are part human and part machine may be a long way off, but researchers say they now may be getting closer. In a study published in ACS’ journal Nano Letters, they report development of a coating that makes nanoelectronics much more stable in conditions mimicking those in the human body. The advance could also aid in the development of very small implanted medical devices for monitoring health and disease.

Charles Lieber and colleagues note that nanoelectronic devices with nanowire components have unique abilities to probe and interface with living cells. They are much smaller than most implanted medical devices used today. For example, a pacemaker that regulates the heart is the size of a U.S. 50-cent coin, but nanoelectronics are so small that several hundred such devices would fit in the period at the end of this sentence. Laboratory versions made of silicon nanowires can detect disease biomarkers and even single virus cells, or record heart cells as they beat. Lieber’s team also has integrated nanoelectronics into living tissues in three dimensions — creating a “cyborg tissue.” One obstacle to the practical, long-term use of these devices is that they typically fall apart within weeks or days when implanted. In the current study, the researchers set out to make them much more stable.

They found that coating silicon nanowires with a metal oxide shell allowed nanowire devices to last for several months. This was in conditions that mimicked the temperature and composition of the inside of the human body. In preliminary studies, one shell material appears to extend the lifespan of nanoelectronics to about two years.

Source: http://www.acs.org/

How To Protect Laptops From Heat Generation

As smartphones, tablets and other gadgets become smaller and more sophisticated, the heat they generate while in use increases. This is a growing problem because it can cause the electronics inside the gadgets to fail. Conventional wisdom suggests the solution is to keep the guts of these gadgets cool. But a new University at Buffalo research paper hints at the opposite: that is, to make laptops and other portable electronic devices more robust, more heat might be the answer.
electric current in a narrow channel

Electric current in a narrow channel

We’ve found that it’s possible to protect nanoelectronic devices from the heat they generate in a way that preserves how these devices function,” said Jonathan Bird, UB professor of electrical engineering. “This will hopefully allow us to continue developing more powerful smartphones, tablets and other devices without having a fundamental meltdown in their operation due to overheating.”
The paper, “Formation of a protected sub-band for conduction in quantum point contacts under extreme biasing,” was published Jan. 19 in the journal Nature Nanotechnology. It is available at the following link:
http://bit.ly/1ikkkHg.
Source: http://www.buffalo.edu/