A new step towards using graphene in electronic applications

(A) This image is a diagram of molecular precursors, the resulting graphene nanoribbons and the heterostructured ones. (B) Tunnel microscopy images of the heterostructures synthesized on gold surfaces. Credit: UPV/EHU

Few materials have received as much attention from the scientific world or have raised so many hopes with a view to their potential deployment in new applications as graphene has. This is largely due to its superlative properties: it is the thinnest material in existence, almost transparent, the strongest, the stiffest and at the same time the most strechable, the best thermal conductor, the one with the highest intrinsic charge carrier mobility, plus many more fascinating features. Specifically, its electronic properties can vary enormously through its confinement inside nanostructured systems, for example. That is why ribbons or rows of graphene with nanometric widths are emerging as tremendously interesting electronic components. On the other hand, due to the great variability of electronic properties upon minimal changes in the structure of these nanoribbons, exact control on an atomic level is an indispensable requirement to make the most of all their potential.

The lithographic techniques used in conventional nanotechnology do not yet have such resolution and precision. In the year 2010, however, a way was found to synthesise nanoribbons with atomic precision by means of the so-called molecular self-assembly. 

Molecules designed for this purpose are deposited onto a surface in such a way that they react with each other and give rise to perfectly specified graphene nanoribbons by means of a highly reproducible process and without any other external mediation than heating to the required temperature. In 2013 a team of scientists from the University of Berkeley and the Centre for Materials Physics (CFM), a mixed CSIC (Spanish National Research Council) and UPV/EHU (University of the Basque Country) centre, extended this very concept to new molecules that were forming wider graphene nanoribbons and therefore with new electronic properties. This same group has now managed to go a step further by creating, through this self-assembly, heterostructures that blend segments of graphene nanoribbons of two different widths.

The forming of heterostructures with different materials has been a concept widely used in electronic engineering and has enabled huge advances to be made in conventional electronics. "We have now managed for the first time to form heterostructures of graphene nanoribbons modulating their width on a molecular level with atomic precision. What is more, their subsequent characterisation by means of scanning tunnelling microscopy and spectroscopy, complemented with first principles theoretical calculations, has shown that it gives rise to a system with very interesting electronic properties which include, for example, the creation of what are known as quantum wells," pointed out the scientist Dimas de Oteyza, who has participated in this project. This work, the results of which are being published this very week in the journal Nature Nanotechnology, therefore constitutes a significant success towards the desired deployment of graphene in commercial electronic applications.

Dr Dimas G. de Oteyza, who was previously at Berkeley and at the CFM, is currently working at the Donostia International Physics Center (DIPC) as a Fellow Gipuzkoa.

Source: University of the Basque Country

A medical lab for the home

Microchip for the electrochemical detection of markers. Credit: © Fraunhofer FIT

Fraunhofer FIT demonstrates a mobile wireless system that monitors the health of elderly people in their own homes, using miniature sensors. Besides non-invasive sensors this platform integrates technology to take a blood sample and to determine specific markers in the patient's blood. At its core is the home unit, a compact device located in the patient's home. It incorporates the necessary software as well as sensors and the analytical equipment.

For years, cardiac diseases have been the most important cause of death globally. Mobile assistance systems that monitor vital parameters, e.g. blood pressure or heart rate, of risk patients in their homes could make their lives safer and more satisfying. A platform supporting this kind was developed and tested by researchers from Fraunhofer FIT, the Berlin Charité, T-Systems and several international partners.

Besides non-invasive sensors this platform integrates technology to take a blood sample and to determine specific markers in the patient's blood while the patient is at home. At its core is the home unit, a compact device located in the patient's home. It incorporates the necessary software as well as sensors and the analytical equipment. Wearable sensors for measuring vital parameters can be linked to the home unit, e.g. a pulse oximeter with a Bluetooth module in the patient's ear or a blood pressure monitor that sends its data to the system via WLAN. Using a nanopotentiostat, an electrochemical sensor, the system can measure the patient's glucose, lactate or cholesterol level. In addition, a fluorescence sensor using a laser diode captures the concentration of several cardiac markers.

To detect the risk-indicating markers in the blood, the patient uses a cartridge that she fills with a drop of blood from a prick in her finger. The cartridge is equipped with a microchip and also specially designed, so that the markers in the blood can be detected. "Miniaturized sensors in the home unit, which can detect traces of the markers down to the nano level, analyze the blood sample," says Professor Harald Mathis, head of the department 

'Biomolecular Optical Systems' of the Fraunhofer Institute for Applied Information 

Technology FIT.

The home unit aggregates the sensor data and sends the results to the patient's doctor or a medical center via secure Internet connection. A smartphone app presents the health data and the physician's feedback to the patient.

The system was developed by Fraunhofer FIT in cooperation with Charité and T-Systems Deutschland in the BMBF/EU-funded project Nanoelectronics for Mobile AAL Systems -- MAS.

Source: Fraunhofer-Institut fuer Angewandte Informationstechnik (FIT)

Internet addicts often suffer from additional disorders

Chatting via WhatsApp rather than meeting friends in real life, sharing holiday photos on Facebook rather than showing them in person, playing video games rather than going out. Digital media play an important role in our everyday lives. However, some people spend an excessive amount of time online, and they are unable to break free. Credit: Image courtesy of Ruhr-Universitaet-Bochum

Internet addicts often suffer from concomitant disorders, most frequently from depressive disorders, anxiety disorders and ADHS. PD Dr med. Bert te Wildt studies this phenomenon at the Ruhr-Universität's LWL Clinic for Psychosomatic Medicine and Psychotherapy.

Spectrum of concomitant disorders similar to that in alcohol addicts

The researcher from Bochum has compiled a so-called comorbidity profile of 25 Internet addicts. Each patient presented at least one concomitant disorder. Together with his colleagues, Bert te Wildt examined 25 alcohol addicts for comparison. Their comorbidity profile was quite similar. However, only every other patient in this cohort suffered from a concomitant disorder. "These results highlight the significance of comorbidity for Internet addiction," says te Wildt. He also points out: "This is not a one-way street, the disorders interact." In another study, he found evidence that in a number of patients Internet addiction may be traced back to similar personality structures.

Large numbers presumably undetected

According to estimates, 500,000 Germans in the age bracket from 14 to 64 years suffer from Internet addiction, which most commonly takes the shape of online gaming addiction. The studies conducted by Bert te Wildt's team at the media outpatient clinic in Bochum suggest that many cases remain undetected.

Source: Ruhr-Universitaet-Bochum

World's first ZigBee-based inter-satellite comms system

This image depicts VELOX-I before and after deployment and a picosatellite. Credit: Shuanglong Xie, Guo Xiong Lee, Kay-Soon Low, Erry Gunawan, 2014

Engineers at the Nanyang Technological University in Singapore have successfully piloted the world's first ZigBee-based inter-satellite communication system.

The team at the Satellite Research Centre launched the VELOX-I, which consists of a nanosatellite weighing 3.5 kg and a piggyback picosatellite weighing 1.5 kg, from the two highest points on campus. Both miniature satellites were configured with a ZigBee wireless network and equipped with small sensor nodes that perform functions such as local sensing, distributed computing and data-gathering.

Designed to evaluate the performance of wireless sensor networks (WSNs) in space, the experiment marks a breakthrough in aeronautical engineering. After conducting Received Signal Strength Indicator tests on the satellites' radio frequency modules, a maximum range of 1 km was found to be achievable for inter-satellite communication in the campus environment. An even longer communication range can be expected in free space, due to the absence of signal attenuation caused by fading and diffraction.

To estimate the range of inter-satellite communication in free space, the team applied a link budget analysis based on the Friis transmission equation, deriving an average theoretical distance of 4.186 km and a maximum of 15.552 km. Published in the special issue of Unmanned Systems, these findings present a compelling case for further studies into inter-satellite communication systems with more complex designs.

In addition to their high performance in inter-satellite communication, WSNs are also remarkably suitable for intra-satellite communication. The team found that by replacing internally wired connections with wireless links, a satellite's mass could be reduced by as much as 10%. With the twin pressures of minimising development costs and maximising risk diversification imposing major constraints on satellite design, the production of comprehensive yet lightweight systems could benefit significantly from WSNs.

Although WSNs have been used in a wide range of applications in recent years, their use in space applications has, until now, remained limited. The Singaporean team's data-driven survey has established a sound platform for future formation-flying satellite missions, and seems poised to create subsequent revolutions in space.

Source: World Scientific

Li-fi protocol allows use of the Internet at the speed of light

Sisoft Company in Mexico has developed a technology that can illuminate a large work space, an auditorium or an office, while providing full mobile internet to every device that comes into the range of the light spectrum. Credit: SISOFT

Sisoft Company in Mexico has developed a technology that can illuminate a large work space, an auditorium or an office, while providing full mobile internet to every device that comes into the range of the light spectrum.

The Mexican group managed to transmit audio, video and Internet across the spectrum of light emitted by LED lamps. This new technology, called Li-Fi or light fidelity, is presented as an alternative to Wi-Fi because it will maximize the original provided speed of the internet to offer safer data transfer and a transfer rate of up to 10 gigabytes per second.

The Li-Fi device circulates data via LEDs that emit an intermittent flicker at a speed imperceptible to the human eye. "As Wi-Fi uses cables to spread our connections, wireless transmission Li-Fi uses LED lamps that emit high brightness light," said Arturo Campos Fentanes, CEO of Sisoft in Mexico.

Another advantage in comparison to Wi-Fi is that there is no way to hack the signal since the internet is transmitted by light, there is no way to "steal it." Furthermore, it can be installed in hospitals areas that use radiation apparatus and generally block or distort internet signal, Campos Fentanes said.

With this new technology expansion through the market is seeked, with lower costs and a service increased by five thousand percent internet speed. Currently in Mexico the highest transfer rate is 200 megabytes per second. Just to get an idea, with Li-Fi you could quickly download an entire HD movie in just 45 seconds.

Also known as visible light communications (VLC), this technology began with an internet speed of two Gigabits per second, but Sisoft along with researchers from the Autonomous Technological Institute of Mexico (ITAM) adapted the system to be multiplied five times.

Campos Fentanes explained that the first experiments were conducted with audio, in which a cable is connected via 3.5 mm audio Jack from a smartphone to a protoboard table to transform the auditory signal in optical waves. That way a special emitter transmits data across the spectrum of light generated by an LED lamp and is captured by a receptor located in a speaker that reproduces sound.

For wireless internet transmission, the mechanics is similar. The station developed by Sisoft of Mexico stands above the router device that distributes the internet signal and a lamp-LED is incorporated to maximize the speed of data transfer. Light will emulate an antenna, but only the electronic apparatus that has the receptor for the "optical audio" signal and is inside the range of the halo of light will have a connection. 

Source: Investigación y Desarrollo

That smartphone is giving your thumbs superpowers

While neuroscientists have long studied brain plasticity in expert groups--musicians or video gamers, for instance--smartphones present an opportunity to understand how regular life shapes the brains of regular people. Credit: © Antonioguillem / Fotolia

When people spend time interacting with their smartphones via touchscreen, it actually changes the way their thumbs and brains work together, according to a report in the Cell Press journal Current Biology on December 23. More touchscreen use in the recent past translates directly into greater brain activity when the thumbs and other fingertips are touched, the study shows.

"I was really surprised by the scale of the changes introduced by the use of smartphones," says Arko Ghosh of the University of Zurich and ETH Zurich in Switzerland. "I was also struck by how much of the inter-individual variations in the fingertip-associated brain signals could be simply explained by evaluating the smartphone logs."

It all started when Ghosh and his colleagues realized that our newfound obsession with smartphones could be a grand opportunity to explore the everyday plasticity of the human brain. Not only are people suddenly using their fingertips, and especially their thumbs, in a new way, but many of us are also doing it an awful lot, day after day. Not only that, but our phones are also keeping track of our digital histories to provide a readymade source of data on those behaviors.

Ghosh explains it this way: "I think first we must appreciate how common personal digital devices are and how densely people use them. What this means for us neuroscientists is that the digital history we carry in our pockets has an enormous amount of information on how we use our fingertips (and more)."

While neuroscientists have long studied brain plasticity in expert groups--musicians or video gamers, for instance--smartphones present an opportunity to understand how regular life shapes the brains of regular people.

To link digital footprints to brain activity in the new study, Ghosh and his team used electroencephalography (EEG) to record the brain response to mechanical touch on the thumb, index, and middle fingertips of touchscreen phone users in comparison to people who still haven't given up their old-school mobile phones.

The researchers found that the electrical activity in the brains of smartphone users was 

enhanced when all three fingertips were touched. In fact, the amount of activity in the cortex of the brain associated with the thumb and index fingertips was directly proportional to the intensity of phone use, as quantified by built-in battery logs. The thumb tip was even sensitive to day-to-day fluctuations: the shorter the time elapsed from an episode of intense phone use, the researchers report, the larger was the cortical potential associated with it.

The results suggest to the researchers that repetitive movements over the smooth touchscreen surface reshape sensory processing from the hand, with daily updates in the brain's representation of the fingertips. And that leads to a pretty remarkable idea: "We propose that cortical sensory processing in the contemporary brain is continuously shaped by personal digital technology," Ghosh and his colleagues write.

What exactly this influence of digital technology means for us in other areas of our lives is a question for another day. The news might not be so good, Ghosh and colleagues say, noting evidence linking excessive phone use with motor dysfunctions and pain.

Source: Cell Press

The economy of bitcoins: New ways to study social action on markets

ETH's researchers decipher the dynamics behind the cryptocurrency Bitcoin.
Credit: © ulchik74 / Fotolia

Anyone who strolls around the Kreuzberg district of Berlin, can't help but notice them -- the small signs on the doors of shops and cafes "Bitcoins accepted." Customers pay for their shirt or their cappuccino with their Smartphone instead of with bank notes or credit cards. The digital currency Bitcoin makes all this possible.

"The image of Bitcoin has changed fundamentally," explains David Garcia, a post-doctoral researcher with the Chair of Systems Design held by Professor Frank Schweitzer. "Bitcoins used to be the reserve of hackers and computer nerds. Today, hipsters pay for drinks with them and they are accepted in the online shops of large companies." Garcia, together with his colleagues Claudio Tessone, Pavlin Mavrodiev and Nicolas Perony, has just published a study on the social dynamics of the Bitcoin economy in the Journal of the Royal Society: Interface.

Internet activity determines exchange rates

For research the success of the digital currency (see box) is a stroke of luck as all data on every transaction carried out in Bitcoin are available in anonymised form on the Internet. Consequently, Garcia and his colleagues are able to study the Bitcoin economy using corresponding algorithms. This idea saw the light of day when they noticed that the 50,000-fold market value increase in the digital currency in just three and a half years went hand in hand with a 10,000 percent increase in Google searches for Bitcoin. The researchers hypothesise that the increase in the value of Bitcoins is markedly accelerated by activities on the Internet, in particular the search for information and interaction in the social media.

To test their hypothesis the researchers examined four different socio-economic parameters: the development of the Bitcoin user base, the price developments of the currency over time, the search for information about Bitcoin on Google and in Wikipedia (more than six million inquiries) and the exchange of information about Bitcoin on Twitter (almost seven million Tweets). In fact, over the past three the researchers established years major correlations between price developments, the number of new Bitcoin users, searches on the Internet and Tweets.

At the same time, they discovered two positive feedback loops which basically reproduced the laws of the "analogous" economy. The growing popularity of Bitcoins on the Internet leads to growing demand which, in turn, encourages activity in the social media. This all results in a higher price for Bitcoins. The second feedback concerns the user base: the more users become part of the Bitcoin transaction network, the higher the price because Bitcoins are not issued in line with demand but in an automated fashion at regular intervals. This means it is possible to calculate the available amount at any time. One negative feedback is, however, surprising. Prior to a major slump in the price of the currency, there was a dramatic increase in Bitcoin activity on the Internet. "Big changes in Internet and social media activities lead to substantial price fluctuations," comments Nicolas Perony, co-author of the article.

Understanding markets and social dynamics

Perony is convinced that the quantitative analysis of social phenomena on the Internet has major potential. "With digital currencies we can observe aspects of the economy that we didn't have access to with cash. This gives us greater understanding of how markets actually function." According to the authors, the methodology described in the article could be applied to other areas in society, too. The Bitcoin mining network, which issues the currency, already harnesses computing power today which is three hundred times bigger than that of the 500 most powerful supercomputers together. "The big question is how such a high-performance system could be used for collaborative activities which go beyond the production of money," comments Perony. One possibility would be, for instance, collaborative research in a global network or the decentralised ownership of specific goods managed by a global network. Bitcoms do not belong to anyone. Buyers merely acquire the right to use a specific amount of them. This study already outlines today the tools for accurately quantifying and analysing the social dynamics of collaborative systems of this kind in the future.

The meteoric rise of Bitcoin

The Bitcoin success story began in 2008 with an article about an alternative, digital currency published under the pseudonym Satoshi Nakamoto. In July 2010 Bitcoins were traded for the first time on the Internet exchange Mt. Gox at a rate of US$ 0.06 for 1 Bitcoin. The total value of all Bitcoins was US$ 277,000. By the end of 2013 the market value of all issued Bitcoins had climbed to more than US$ 14 billion whereby during spikes more than US$ 1,000 were paid for one Bitcoin. Today, over four million people use the digital currency. 

Bitcoins are traded in euros, dollars and in Chinese renminbi. Unlike conventional currencies there is no central bank for Bitcoins which has a monopoly for printing money. New Bitcoins are generated by what is known as mining via a global computer network -- currently at a rate of 25 Bitcoins every ten minutes. Transactions are likewise verified and carried out on this network. Even the bankruptcy of important Bitcoin trading exchanges and negative headlines about money laundering and drug purchases on the Internet were not able to undermine confidence in the currency. A few days ago the PC giant Dell announced that it will henceforth accept Bitcoins as payment for products in its online shop.

Source: ETH Zurich

Move over smart cities, the Internet of Things is off to the country

Smart sheep

 Lancaster University is about to take the concept of smart cities out of town. Computer scientists at Lancaster University are investigating how the Internet of Things could work in the countryside.

The Internet of Things - which enables object-to-object communication over the internet and real time data monitoring - has typically been associated with urban environments and until now the countryside has been left out in the cold.

Computer scientist Professor Gordon Blair of Lancaster University has won £171,495 from the Engineering and Physical Sciences Research Council to lead a new project in Conwy, North Wales, which will investigate how the Internet of Things could work in the countryside.

Working with partners at the Centre for Ecology and Hydrology, The British Geological Survey and Bangor University, the project launched on December 1 and will run for 18 months.

Problems from flooding and agricultural pollution to animal movements and drought could all potentially benefit from smart technology in the sticks.

The Internet of Things, which takes everyday objects and hooks them up to the internet, represents a shift in the way we gather and engage with information. Applying this booming technology to the countryside presents challenges – for example how to build a network when there are mountains and trees in the way – but researchers believe the benefits could be huge.

Sheep with digital collars, sensors on riverbanks, rainfall and river flow monitors could all soon form part of the project.

Professor Blair said: “Cities have been the focus of much of the boom in this type of technology – it has been used to keep traffic flowing on our roads, monitor air pollution and even help us find a parking spot on a busy Saturday afternoon. But the countryside faces challenges of its own, from subtle environmental changes to catastrophic events such as flooding. The possibilities of bringing the Internet of Things to the countryside are limitless. The next step will be to identify exactly what will be of most use in the short term and how we will frame the project.”

Source: Lancaster University