Researchers have discovered a way to remove specific fears from the brain, using a combination of artificial intelligence and brain scanning technology.
Their technique, published in the inaugural edition of Nature Human Behaviour, could lead to a new way of treating patients with conditions such as post-traumatic stress disorder (PTSD) and phobias.
The challenge then was to find a way to reduce or remove the fear memory, without ever consciously evoking it
Fear related disorders affect around one in 14 people and place considerable pressure on mental health services. Currently, a common approach is for patients to undergo some form of aversion therapy, in which they confront their fear by being exposed to it in the hope they will learn that the thing they fear isn’t harmful after all. However, this therapy is inherently unpleasant, and many choose not to pursue it. Now a team of neuroscientists from the University of Cambridge, Japan and the USA, has found a way of unconsciously removing a fear memory from the brain.
The team developed a method to read and identify a fear memory using a new technique called ‘Decoded Neurofeedback’. The technique used brain scanning to monitor activity in the brain, and identify complex patterns of activity that resembled a specific fear memory. In the experiment, a fear memory was created in 17 healthy volunteers by administering a brief electric shock when they saw a certain computer image. When the pattern was detected, the researchers over-wrote the fear memory by giving their experimental subjects a reward.
Dr. Ben Seymour, of the University of Cambridge’s Engineering Department, was one of the authors on the study. He explained the process:
“The way information is represented in the brain is very complicated, but the use of artificial intelligence (AI) image recognition methods now allow us to identify aspects of the content of that information. When we induced a mild fear memory in the brain, we were able to develop a fast and accurate method of reading it by using AI algorithms. The challenge then was to find a way to reduce or remove the fear memory, without ever consciously evoking it.
“We realised that even when the volunteers were simply resting, we could see brief moments when the pattern of fluctuating brain activity had partial features of the specific fear memory, even though the volunteers weren’t consciously aware of it. Because we could decode these brain patterns quickly, we decided to give subjects a reward – a small amount of money – every time we picked up these features of the memory.”
The team repeated the procedure over three days. Volunteers were told that the monetary reward they earned depended on their brain activity, but they didn’t know how. By continuously connecting subtle patterns of brain activity linked to the electric shock with a small reward, the scientists hoped to gradually and unconsciously override the fear memory.
Dr Ai Koizumi, of the Advanced Telecommunicatons Research Institute International, Kyoto and Centre of Information and Neural Networks, Osaka, led the research:
“In effect, the features of the memory that were previously tuned to predict the painful shock, were now being re-programmed to predict something positive instead.”
The team then tested what happened when they showed the volunteers the pictures previously associated with the shocks.
“Remarkably, we could no longer see the typical fear skin-sweating response. Nor could we identify enhanced activity in the amygdala – the brain’s fear centre,” she continued. “This meant that we’d been able to reduce the fear memory without the volunteers ever consciously experiencing the fear memory in the process.”
Although the sample size in this initial study was relatively small, the team hopes the technique can be developed into a clinical treatment for patients with PTSD or phobias.
“To apply this to patients, we need to build a library of the brain information codes for the various things that people might have a pathological fear of, say, spiders” adds Dr Seymour. “Then, in principle, patients could have regular sessions of Decoded Neurofeedback to gradually remove the fear response these memories trigger.”
Such a treatment could have major benefits over traditional drug based approaches. Patients could also avoid the stress associated with exposure therapies, and any side-effects resulting from those drugs.
Learn more: Reconditioning the brain to overcome fear
Launched in July this year, Pokémon Go has become a global phenomenon, reaching 500 million downloads within two months of release.
The augmented reality game, designed for mobile devices, allows users to capture, battle and train virtual creatures called Pokémon that appear on screen as if part of the real-world environment.
But can the game’s enormous success deliver any lessons to the fields of natural history and conservation?
A new paper by a group of researchers from the universities of Oxford and Cambridge, UNEP World Conservation Monitoring Centre, and University College London (UCL) explores whether Pokémon Go’s success in getting people out of their homes and interacting with virtual ‘animals’ could be replicated to redress what is often perceived as a decline in interest in the natural world among the general public.
Or, could the game’s popularity pose more problems than opportunities for conservation?
Study author Leejiah Dorward, a doctoral candidate in Oxford University’s Department of Zoology, said: ‘When Pokémon Go first came out, one of the most striking things was its similarity with many of the concepts seen in natural history and conservation. The basic facts and information about Pokémon Go make it sound like an incredibly successful citizen science project, rather than a smartphone game.
‘We wanted to explore how the success of Pokémon Go might create opportunities or challenges for the conservation movement.’
Co-author John C Mittermeier, a doctoral candidate in Oxford’s School of Geography and the Environment, said: ‘There is a widespread belief that interest in natural history is waning and that people are less interested in spending time outside and exploring the natural world.
‘Pokémon Go is only one step removed from natural history activities like bird watching or insect collecting: Pokémon exist as “real” creatures that can be spotted and collected, and the game itself has been getting people outdoors. What’s going on here, and can we as conservationists take advantage of it?’
In the paper, the researchers explain that Pokémon Go has been shown to inspire high levels of behavioural change among its users, with people making significant adjustments to their daily routines and to the amount of time spent outside in order to increase their chances of encountering target ‘species’. There is also evidence that users are discovering non-virtual wildlife while playing Pokémon Go, leading to the Twitter hashtag #Pokeblitz that helps people identify ‘real’ species found and photographed during play.
Pokémon Go, the researchers write, exposes users first hand to basic natural history concepts such as species’ habitat preferences and variations in abundance. ‘Grass Pokémon’, for example, tend to appear in parks, while water-related types are more likely to be found close to bodies of water. There are also four regional species that are continent restricted: Tauros to the Americas, Mr Mime to Western Europe, Farfetch’d to Asia, and the marsupial-like Kangaskhan to Australasia. This differentiation captures a fundamental aspect of natural history observation – that exploring new habitats and continents will lead to encounters with different species.
And hundreds of people congregated near New York’s Central Park one night over the summer to try to find a rare Vaporeon – something that will sound familiar to birdwatchers used to similar gatherings to see a rare species.
The authors write: ‘The spectacular success of Pokémon Go provides significant lessons for conservation. Importantly, it suggests that conservation is continuing to lag behind Pokémon in efforts to inspire interest in its portfolio of species.
‘There is clear potential to modify Pokémon Go itself to increase conservation content and impact above and beyond simply bringing gamers into closer physical proximity to non-human wildlife as a by-product of the game. Pokémon Go could be adapted to enhance conservation benefits by: a) making Pokémon biology and ecology more realistic; b) adding real species to the Pokémon Go universe to introduce those species to a huge number of users, and creating opportunities to raise awareness about them; c) deliberately placing Pokémon in more remote natural settings rather than urban areas to draw people to experience non-urban nature; or d) adding a mechanism for users to catalogue real species, building on the popularity of the “Pokeblitz” concept.
‘Less directly, lessons from Pokémon Go could be applied to conservation through the development of new conservation-focused augmented reality (AR) games. Following the model of Pokémon Go, games that encourage users to look for real species could provide a powerful tool for education and engagement. AR could also be used in zoos and protected areas to provide visitors with information about species and their habitats.’
However, the researchers caution that the success of Pokémon Go could also bring challenges: for example, it may be that this type of augmented reality – featuring engaging, brightly coloured fictional creatures – could replace people’s desire to interact with real-world nature, or the focus on catching and battling Pokémon may encourage exploitation of wildlife. There has also been controversy in the Netherlands, where Pokémon Go players have been blamed for damage caused to a protected dune system south of The Hague.
Co-author Dr Chris Sandbrook, a senior lecturer at UNEP World Conservation Monitoring Centre, said: ‘Just getting people outside does not guarantee a conservation success from Pokémon Go. It might actually make things worse – for example, if interest in finding a rare Vaporeon replaces concern for real species threatened with extinction. Real nature could be seen as just a mundane backdrop for more exciting virtual wildlife.’
Leejiah Dorward added: ‘One of the positive things about Pokémon Go is that there’s a very low barrier for entry. As long as you have a smartphone, you can play – and the game itself does a lot of things for you. Finding ways to break down barriers to engagement with real-life nature is a priority for conservation. Pokémon are also relatable “characters”, whereas modern conservation tends to frame itself purely in scientific terms, which may be off-putting to many.
‘There is something called the biophilia hypothesis, which suggests that people have an in-built affinity with nature and a desire to explore the natural world. If that’s one of the reasons Pokémon Go has proved to be so popular – because it’s a natural history proxy – then that could be a huge boost to conservation. It’s possible that the desire to connect with nature is there and to get people to engage with conservation we just need to “sell” it correctly.’
Originally founded in 1209, it is the second-oldest university in English-speaking areas, and the world’s third-oldest surviving university. The university grew out of an association of scholars that was formed in 1209, early records suggest, by scholars leaving Oxford after a dispute with townsfolk. The two “ancient universities” have many common features and are often jointly referred to as Oxbridge.
Today, Cambridge is formed from a variety of institutions which include 31 constituent colleges and comprehensive academic departments which are organised into six academic schools. All these organisations occupy different locations in the town including purposely-built sites and the student life is found in the arts, sport clubs and societies. Cambridge has nurtured many prominent alumni, and 90 Nobel laureates have been affiliated with the university. It is also a member of various academic associations and forms part of the ‘golden triangle’ of English universities.
University of Cambridge research articles from Innovation Toronto
- DNA in blood can track cancer development and response in real time – November 9, 2015
- Cambridge Researchers Make Lithium-Air Battery Tech Breakthrough – November 2, 2015
- Entanglement at heart of ‘two-for-one’ singlet fission could double solar cell output – October 29, 2015
- New glass manufacturing technique could enable design of hybrid glasses and revolutionise gas storage – August 29, 2015
- On the origin of (robot) species – August 16, 2015
- Robots learn to evolve and improve – August 13, 2015
- Can Computers be Creative? – July 7, 2015
- ‘Pick & mix’ smart materials for robotics – June 24, 2015
- Silent flights: How owls could help make wind turbines and planes quieter – June 22, 2015
- New gold standard established for open and reproducible research – May 7, 2015
- Alzheimer’s breakthrough: scientists home in on molecule which halts development of disease – February 16, 2015
- Responsive material could be the ‘golden ticket’ of sensing – January 9, 2015
- Finally, a method for recycling of plastic-aluminum laminates – December 30, 2014
- Airplanes Go Hybrid-Electric – December 26, 2014
- Cambridge breakthrough in artifical muscle research – November 21, 2014
- New research lights the way to super-fast computers – November 9, 2014
- Quick-change materials break the silicon speed limit for computers – September 22, 2014
- First graphene-based flexible display produced – September 15, 2014
- To clean air and beyond: Catching greenhouse gases with advanced membranes – September 7, 2014
- Changing global diets is vital to reducing climate change – September 5, 2014
- Pairing old technologies with new for next generation electronic devices – August 14, 2014
- Cambridge team breaks superconductor world record – July 17, 2014
- Cancer breakthrough as scientists discover how cells spread for the first time paving the way for new treatments to halt disease in its tracks – July 8, 2014
- Revolutionary solar cells double as lasers
- App turns a smartphone into a portable medical diagnostic device
- Holographic diagnostics
- Near error-free wireless detection made possible | wireless tag detection
- Cells from the eye are inkjet printed for the first time | artificial tissue grafts
- Could Revolutionize Solar Energy: Quantum waves at the heart of organic solar cells
- University of Cambridge Makes a Potential Printing Breakthrough
- 2 for 1 in solar power
- Quantum ‘sealed envelope’ system enables ‘perfectly secure’ information storage
- Future internet aims to sever links with servers
- Maths study of photosynthesis clears the path to developing new super-crops
- Stem cell breakthrough could set up future transplant therapies
- New sensor could prolong the lifespan of high-temperature engines
- How does your garden grow?
- How We’ll Grow The Next Generation Of Buildings With Bacteria
- VIDEO: Electron ‘spin’ key to solar cell breakthrough
- Cost of Arctic methane release could be ‘size of global economy’ warn experts
- From spiders, a material to rival Kevlar
- VIDEO: Carbon ‘candy floss’ could help prevent energy blackouts
- Brain-Scan Lie Detectors Just Don’t Work
- New Synthetic Material mimics the brightest and most vivid colours in nature and changes colour
- Ultrashort Laser Pulses Squeezed Out of Graphene
- Wonder pill cuts risk of arthritis
- Study Led by NUS Scientists Reveals Escalating Cost of Forest Conservation
- Earth feels impact of middle class
- Can Synthetic Biology Save Wildlife?
- Roads could help rather than harm the environment
- Laser-like photons signal major step towards quantum ‘Internet’
- Face of the future rears its head
- Digital records could expose intimate details and personality traits of millions
- Hope for threatened Tasmanian devils
- Scientists produce H2 for fuel cells using an inexpensive catalyst under real-world conditions
- Deep sea bacteria could provide breakthroughs for solar panels
- Humanity’s last invention and our uncertain future
- Proliferation warnings on nuclear “wonder-fuel”
- One Step Closer To Real Medical Tech Breakthrough
- Visions for open evaluation of scientific papers by post-publication peer review
- Therapy over the phone as effective as face-to-face
- Metalysis Sand-to-Metal Breakthrough
- Scientists produce H2 for fuel cells using an inexpensive catalyst under real-world conditions
- “Living furniture” could power laptops and desk lamps
- Breakthrough in search for alien life as scientists manufacture DNA-like molecule which can transmit genetic material
- Workhorse Climate Satellite Goes Silent
- The 4 Factors That Make A Country Ideal For Innovation
- Laser-powered ‘unprinter’ wipes documents in a flash
- New Hybrid Solar Cells Harness More Of The Sun’s Light Spectrum
- Human brain cells created from skin
- First Demonstration of Inkjet-Printed Graphene Electronics
- U.K. Researchers to Test “Artificial Volcano” for Geoengineering the Climate
- Brazil promises 75,000 scholarships in science and technology
- Limit to Nanotechnology Mass-Production?
- Research sheds new light on wall-climbing critters
- Microwaves utilized to convert used motor oil into fuel
- Transgenic chickens get bird flu without passing it on
- Researchers develop interactive, emotion-detecting GPS robot
- Improving Ammonia Synthesis Could Have Major Implications for Agriculture and Energy
- Creation of liver cells from skin cells gives hope in fight against liver disease
- Better speech-recognition technology
- New butterfly-wing technology could foil counterfeiters
- War Is Peace: Can Science Fight Media Disinformation?
- Superb vistas from reborn Hubble
Using the strange properties of tiny particles of gold, researchers have concentrated light down smaller than a single atom, letting them look at individual chemical bonds inside molecules, and opening up new ways to study light and matter.
Single gold atoms behave just like tiny metallic ball bearings in our experiments, with conducting electrons roaming around, which is very different from their quantum life.
For centuries, scientists believed that light, like all waves, couldn’t be focused down smaller than its wavelength, just under a millionth of a metre. Now, researchers led by the University of Cambridge have created the world’s smallest magnifying glass, which focuses light a billion times more tightly, down to the scale of single atoms.
In collaboration with European colleagues, the team used highly conductive gold nanoparticles to make the world’s tiniest optical cavity, so small that only a single molecule can fit within it. The cavity – called a ‘pico-cavity’ by the researchers – consists of a bump in a gold nanostructure the size of a single atom, and confines light to less than a billionth of a metre. The results, reported in the journal Science, open up new ways to study the interaction of light and matter, including the possibility of making the molecules in the cavity undergo new sorts of chemical reactions, which could enable the development of entirely new types of sensors.
According to the researchers, building nanostructures with single atom control was extremely challenging. “We had to cool our samples to -260°C in order to freeze the scurrying gold atoms,” said Felix Benz, lead author of the study. The researchers shone laser light on the sample to build the pico-cavities, allowing them to watch single atom movement in real time.
“Our models suggested that individual atoms sticking out might act as tiny lightning rods, but focusing light instead of electricity,” said Professor Javier Aizpurua from the Center for Materials Physics in San Sebastian in Spain, who led the theoretical section of this work.
“Even single gold atoms behave just like tiny metallic ball bearings in our experiments, with conducting electrons roaming around, which is very different from their quantum life where electrons are bound to their nucleus,” said Professor Jeremy Baumberg of the NanoPhotonics Centre at Cambridge’s Cavendish Laboratory, who led the research.
The findings have the potential to open a whole new field of light-catalysed chemical reactions, allowing complex molecules to be built from smaller components. Additionally, there is the possibility of new opto-mechanical data storage devices, allowing information to be written and read by light and stored in the form of molecular vibrations.
A photoreceptor molecule in plant cells has been found to moonlight as a thermometer after dark – allowing plants to read seasonal temperature changes. Scientists say the discovery could help breed crops that are more resilient to the temperatures expected to result from climate change.
Discovering the molecules that allow plants to sense temperature has the potential to accelerate the breeding of crops resilient to thermal stress and climate change
An international team of scientists led by the University of Cambridge has discovered the ‘thermometer’ molecule that enables plants to develop according to seasonal temperature changes.
Researchers have revealed that molecules called phytochromes – used by plants to detect light during the day – actually change their function in darkness to become cellular temperature gauges that measure the heat of the night.
The new findings, published today in the journal Science, show that phytochromes control genetic switches in response to temperature as well as light to dictate plant development.
At night, these molecules change states, and the pace at which they change is “directly proportional to temperature” say scientists, who compare phytochromes to mercury in a thermometer. The warmer it is, the faster the molecular change – stimulating plant growth.
Farmers and gardeners have known for hundreds of years how responsive plants are to temperature: warm winters cause many trees and flowers to bud early, something humans have long used to predict weather and harvest times for the coming year.
The latest research pinpoints for the first time a molecular mechanism in plants that reacts to temperature – often triggering the buds of spring we long to see at the end of winter.
With weather and temperatures set to become ever more unpredictable due to climate change, researchers say the discovery that this light-sensing molecule moonlights as the internal thermometer in plant cells could help us breed tougher crops.
“It is estimated that agricultural yields will need to double by 2050, but climate change is a major threat to such targets. Key crops such as wheat and rice are sensitive to high temperatures. Thermal stress reduces crop yields by around 10% for every one degree increase in temperature,” says lead researcher Dr Philip Wigge from Cambridge’s Sainsbury Laboratory.
“Discovering the molecules that allow plants to sense temperature has the potential to accelerate the breeding of crops resilient to thermal stress and climate change.”
In their active state, phytochrome molecules bind themselves to DNA to restrict plant growth. During the day, sunlight activates the molecules, slowing down growth.
If a plant finds itself in shade, phytochromes are quickly inactivated – enabling it to grow faster to find sunlight again. This is how plants compete to escape each other’s shade. “Light driven changes to phytochrome activity occur very fast, in less than a second,” says Wigge.
At night, however, it’s a different story. Instead of a rapid deactivation following sundown, the molecules gradually change from their active to inactive state. This is called “dark reversion”.
“Just as mercury rises in a thermometer, the rate at which phytochromes revert to their inactive state during the night is a direct measure of temperature,” says Wigge.
“The lower the temperature, the slower phytochromes revert to inactivity, so the molecules spend more time in their active, growth-suppressing state. This is why plants are slower to grow in winter.
“Warm temperatures accelerate dark reversion, so that phytochromes rapidly reach an inactive state and detach themselves from DNA – allowing genes to be expressed and plant growth to resume.”
Wigge believes phytochrome thermo-sensing evolved at a later stage, and co-opted the biological network already used for light-based growth during the downtime of night.
Some plants mainly use day-length as an indicator of the season. Other species, such as daffodils, have considerable temperature sensitivity, and can flower months in advance during a warm winter.
In fact, the discovery of the dual role of phytochromes provides the science behind a well-known rhyme long used to predict the coming season: Oak before Ash we’ll have a splash, Ash before Oak we’re in for a soak.
Wigge explains: “Oak trees rely much more on temperature, likely using phytochromes as thermometers to dictate development, whereas Ash trees rely on measuring day length to determine their seasonal timing.
“A warmer spring, and consequently a higher likeliness of a hot summer, will result in Oak leafing before Ash. A cold spring will see the opposite. As the British know only too well, a colder summer is likely to be a rain-soaked one.”
The new findings are the culmination of twelve years of research involving scientists from Germany, Argentina and the US, as well as the Cambridge team. The work was done in a model system, a mustard plant called Arabidopsis, but Wigge says the phytochrome genes necessary for temperature sensing are found in crop plants as well.
“Recent advances in plant genetics now mean that scientists are able to rapidly identify the genes controlling these processes in crop plants, and even alter their activity using precise molecular ‘scalpels’,” adds Wigge.
“Cambridge is uniquely well-positioned to do this kind of research as we have outstanding collaborators nearby who work on more applied aspects of plant biology, and can help us transfer this new knowledge into the field.”
A new prototype of a lithium-sulphur battery – which could have five times the energy density of a typical lithium-ion battery – overcomes one of the key hurdles preventing their commercial development by mimicking the structure of the cells which allow us to absorb nutrients.
This gets us a long way through the bottleneck which is preventing the development of better batteries.
Researchers have developed a prototype of a next-generation lithium-sulphur battery which takes its inspiration in part from the cells lining the human intestine. The batteries, if commercially developed, would have five times the energy density of the lithium-ion batteries used in smartphones and other electronics.
The new design, by researchers from the University of Cambridge, overcomes one of the key technical problems hindering the commercial development of lithium-sulphur batteries, by preventing the degradation of the battery caused by the loss of material within it. The results are reported in the journal Advanced Functional Materials.
Working with collaborators at the Beijing Institute of Technology, the Cambridge researchers based in Dr Vasant Kumar’s team in the Department of Materials Science and Metallurgy developed and tested a lightweight nanostructured material which resembles villi, the finger-like protrusions which line the small intestine. In the human body, villi are used to absorb the products of digestion and increase the surface area over which this process can take place.
In the new lithium-sulphur battery, a layer of material with a villi-like structure, made from tiny zinc oxide wires, is placed on the surface of one of the battery’s electrodes. This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused.
“It’s a tiny thing, this layer, but it’s important,” said study co-author Dr Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy. “This gets us a long way through the bottleneck which is preventing the development of better batteries.”
A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. The most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode.
The crystal structure of the electrode materials determines how much energy can be squeezed into the battery. For example, due to the atomic structure of carbon, each carbon atom can take on six lithium ions, limiting the maximum capacity of the battery.
Sulphur and lithium react differently, via a multi-electron transfer mechanism meaning that elemental sulphur can offer a much higher theoretical capacity, resulting in a lithium-sulphur battery with much higher energy density. However, when the battery discharges, the lithium and sulphur interact and the ring-like sulphur molecules transform into chain-like structures, known as a poly-sulphides. As the battery undergoes several charge-discharge cycles, bits of the poly-sulphide can go into the electrolyte, so that over time the battery gradually loses active material.
The Cambridge researchers have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. The layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. The concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight.
“Changing from stiff nickel foam to flexible carbon fibre mat makes the layer mimic the way small intestine works even further,” said study co-author Dr Yingjun Liu.
This functional layer, like the intestinal villi it resembles, has a very high surface area. The material has a very strong chemical bond with the poly-sulphides, allowing the active material to be used for longer, greatly increasing the lifespan of the battery.
“This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging,” said the study’s lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. “By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries.”
For the time being, the device is a proof of principle, so commercially-available lithium-sulphur batteries are still some years away. Additionally, while the number of times the battery can be charged and discharged has been improved, it is still not able to go through as many charge cycles as a lithium-ion battery. However, since a lithium-sulphur battery does not need to be charged as often as a lithium-ion battery, it may be the case that the increase in energy density cancels out the lower total number of charge-discharge cycles.
“This is a way of getting around one of those awkward little problems that affects all of us,” said Coxon. “We’re all tied in to our electronic devices – ultimately, we’re just trying to make those devices work better, hopefully making our lives a little bit nicer.”
A new design for transistors which operate on ‘scavenged’ energy from their environment could form the basis for devices which function for months or years without a battery, and could be used for wearable or implantable electronics.
If we were to draw energy from a typical AA battery based on this design, it would last for a billion years.
A newly-developed form of transistor opens up a range of new electronic applications including wearable or implantable devices by drastically reducing the amount of power used. Devices based on this type of ultralow power transistor, developed by engineers at the University of Cambridge, could function for months or even years without a battery by ‘scavenging’ energy from their environment.
Using a similar principle to a computer in sleep mode, the new transistor harnesses a tiny ‘leakage’ of electrical current, known as a near-off-state current, for its operations. This leak, like water dripping from a faulty tap, is a characteristic of all transistors, but this is the first time that it has been effectively captured and used functionally. The results, reported in the journal Science, open up new avenues for system design for the Internet of Things, in which most of the things we interact with every day are connected to the Internet.
The transistors can be produced at low temperatures and can be printed on almost any material, from glass and plastic to polyester and paper. They are based on a unique geometry which uses a ‘non-desirable’ characteristic, namely the point of contact between the metal and semiconducting components of a transistor, a so-called ‘Schottky barrier.’
“We’re challenging conventional perception of how a transistor should be,” said Professor Arokia Nathan of Cambridge’s Department of Engineering, the paper’s co-author. “We’ve found that these Schottky barriers, which most engineers try to avoid, actually have the ideal characteristics for the type of ultralow power applications we’re looking at, such as wearable or implantable electronics for health monitoring.”
The new design gets around one of the main issues preventing the development of ultralow power transistors, namely the ability to produce them at very small sizes. As transistors get smaller, their two electrodes start to influence the behaviour of one another, and the voltages spread, meaning that below a certain size, transistors fail to function as desired. By changing the design of the transistors, the Cambridge researchers were able to use the Schottky barriers to keep the electrodes independent from one another, so that the transistors can be scaled down to very small geometries.
The design also achieves a very high level of gain, or signal amplification. The transistor’s operating voltage is less than a volt, with power consumption below a billionth of a watt. This ultralow power consumption makes them most suitable for applications where function is more important than speed, which is the essence of the Internet of Things.
“If we were to draw energy from a typical AA battery based on this design, it would last for a billion years,” said Dr Sungsik Lee, the paper’s first author, also from the Department of Engineering. “Using the Schottky barrier allows us to keep the electrodes from interfering with each other in order to amplify the amplitude of the signal even at the state where the transistor is almost switched off.”
“This is an ingenious transistor concept,” said Professor Gehan Amaratunga, Head of the Electronics, Power and Energy Conversion Group at Cambridge’s Engineering Department. “This type of ultra-low power operation is a pre-requisite for many of the new ubiquitous electronics applications, where what matters is function – in essence ‘intelligence’ – without the demand for speed. In such applications the possibility of having totally autonomous electronics now becomes a possibility. The system can rely on harvesting background energy from the environment for very long term operation, which is akin to organisms such as bacteria in biology.”
Hydrogen is often described as the fuel of the future, particularly when applied to hydrogen-powered fuel cell vehicles. One of the main obstacles facing this technology – a potential solution to future sustainable transport – has been the lack of a lightweight, safe on-board hydrogen storage material.
A major new discovery by scientists at the universities of Oxford, Cambridge and Cardiff in the UK, and the King Abdulaziz City for Science and Technology (KACST) in Saudi Arabia, has shown that hydrocarbon wax rapidly releases large amounts of hydrogen when activated with catalysts and microwaves.
This discovery of a potential safe storage method, reported in the Nature journal Scientific Reports, could pave the way for widespread adoption of hydrogen-fuelled cars.
Study co-author Professor Peter Edwards, who leads the KACST-Oxford Petrochemical Research Centre (KOPRC), a KACST Centre of Excellence in Petrochemicals at Oxford University, said: ‘This discovery of a safe, efficient hydrogen storage and production material can open the door to the large-scale application of fuel cells in vehicles.’
Co-author Dr Tiancun Xiao, a senior research fellow at Oxford University, said: ‘Our discovery – that hydrogen can be easily and instantly extracted from wax, a benign material that can be manufactured from sustainable processes – is a major step forward. Wax will not catch fire or contaminate the environment. It is also safe for drivers and passengers.’
Co-author Professor Hamid Al-Megren, from the Materials Research Institute at KACST, said: ‘This is an exciting development – it will allow society to utilise fossil fuels or renewable-derived wax to generate on-board hydrogen for fuel cell applications without releasing any carbon dioxide into the air.’
Hydrocarbons are natural, hydrogen-rich resources with well-established infrastructures. The research team has developed highly selective catalysts with the assistance of microwave irradiation, which can extract hydrogen from hydrocarbons instantly through a non-oxidative dehydrogenation process. This will help unlock the longstanding bottleneck hindering the widespread adoption of hydrogen fuel technology.
Co-author Professor Angus Kirkland, from the Department of Materials at Oxford University and Science Director at the new electron Physical Science Imaging Centre (ePSIC) at Harwell Science and Innovation Campus, described the breakthrough as an exemplar of how Oxford is able to respond to key academic and industrial problems by using interdisciplinary resources and expertise.
Co-author Professor Sir John Meurig Thomas, from the Department of Materials Science and Metallurgy at the University of Cambridge, said the work could be extended so that many of the liquid components of refined petroleum and inexpensive solid catalysts can pave the way for the generation of massive quantities of high-purity hydrogen for other commercial uses, including CO2-free energy production.
Professor Edwards added: ‘Instead of burning fossil fuels, leading to CO2, we use them to generate hydrogen, which with fuel cells produces electric power and pure water. This is the future – transportation without CO2 and hot air.’
Researchers from the Graphene Flagship use layered materials to create an all-electrical quantum light emitting diodes (LED) with single-photon emission. These LEDs have potential as on-chip photon sources in quantum information applications.
Atomically thin LEDs emitting one photon at a time have been developed by researchers from the Graphene Flagship. Constructed of layers of atomically thin materials, including transition metal dichalcogenides (TMDs), graphene, and boron nitride, the ultra-thin LEDs showing all-electrical single photon generation could be excellent on-chip quantum light sources for a wide range of photonics applications for quantum communications and networks. The research, reported in Nature Communications, was led by the University of Cambridge, UK.
The ultra-thin devices reported in the paper are constructed of thin layers of different layered materials, stacked together to form a heterostructure. Electrical current is injected into the device, tunnelling from single-layer graphene, through few-layer boron nitride acting as a tunnel barrier, and into the mono- or bi-layer TMD material, such as tungsten diselenide (WSe2), where electrons recombine with holes to emit single photons. At high currents, this recombination occurs across the whole surface of the device, while at low currents, the quantum behaviour is apparent and the recombination is concentrated in highly localised quantum emitters.
All-electrical single photon emission is a key priority for integrated quantum optoelectronics. Typically, single photon generation relies on optical excitation and requires large-scale optical set-ups with lasers and precise alignment of optical components. This research brings on-chip single photon emission for quantum communication a step closer. Professor Mete Atatüre (Cavendish Laboratory, University of Cambridge, UK), co-author of the research, explains “Ultimately, in a scalable circuit, we need fully integrated devices that we can control by electrical impulses, instead of a laser that focuses on different segments of an integrated circuit. For quantum communication with single photons, and quantum networks between different nodes – for example, to couple qubits – we want to be able to just drive current, and get light out. There are many emitters that are optically excitable, but only a handful are electrically driven” In their devices, a modest current of less than 1 µA ensures that the single-photon behaviour dominates the emission characteristics.
The layered structure of TMDs makes them ideal for use in ultra-thin heterostructures for use on chips, and also adds the benefit of atomically precise layer interfacing. The quantum emitters are highly localised in the TMD layer and have spectrally sharp emission spectra. The layered nature also offers an advantage over some other single-photon emitters for feasible and effective integration into nanophotonic circuits. Professor Frank Koppens (ICFO, Spain), leader of Work Package 8 – Optoelectronics and Photonics, adds “Electrically driven single photon sources are essential for many applications, and this first realisation with layered materials is a real milestone. This ultra-thin and flexible platform offers high levels of tunability, design freedom, and integration capabilities with nano-electronic platforms including silicon CMOS.”
This research is a fantastic example of the possibilities that can be opened up with new discoveries about materials. Quantum dots were discovered to exist in layered TMDs only very recently, with research published simultaneously in early 2015 by several different research groups including groups currently working within the Graphene Flagship. Dr Marek Potemski and co-workers working at CNRS (France) in collaboration with researchers at the University of Warsaw (Poland) discovered stable quantum emitters at the edges of WSe2 monolayers, displaying highly localised photoluminescence with single-photon emission characteristics. Professor Kis and colleagues working at ETH Zurich and EPFL (Switzerland) also observed single photon emitters with narrow linewidths in WSe2. At the same time, Professor van der Zant and colleagues from Delft University of Technology (Netherlands), working with researchers at the University of Münster (Germany) observed that the localised emitters in WSe2 are due to trapped excitons, and suggested that they originate from structural defects. These quantum emitters have the potential to supplant research into the more traditional quantum dot counterparts because of their numerous benefits of the ultrathin devices of the layered structures.
With this research, quantum emitters are now seen in another TMD material, namely tungsten disulphide (WS2). Professor Atatüre says “We chose WS2 because it has higher bandgap, and we wanted to see if different materials offered different parts of the spectra for single photon emission. With this, we have shown that the quantum emission is not a unique feature of WSe2, which suggests that many other layered materials might be able to host quantum dot-like features as well.”
Researchers have observed quantum effects in electrons by squeezing them into one-dimensional ‘quantum wires’ and observing the interactions between them. The results could be used to aid in the development of quantum technologies, including quantum computing.
Scientists have controlled electrons by packing them so tightly that they start to display quantum effects, using an extension of the technology currently used to make computer processors. The technique, reported in the journal Nature Communications, has uncovered properties of quantum matter that could pave a way to new quantum technologies.
The ability to control electrons in this way may lay the groundwork for many technological advances, including quantum computers that can solve problems fundamentally intractable by modern electronics. Before such technologies become practical however, researchers need to better understand quantum, or wave-like, particles, and more importantly, the interactions between them.
Squeezing electrons into a one-dimensional ‘quantum wire’ amplifies their quantum nature to the point that it can be seen, by measuring at what energy and wavelength (or momentum) electrons can be injected into the wire.
“Think of a crowded train carriage, with people standing tightly packed all the way down the centre of the carriage,” said Professor Christopher Ford of the University of Cambridge’s Cavendish Laboratory, one of the paper’s co-authors. “If someone tries to get in a door, they have to push the people closest to them along a bit to make room. In turn, those people push slightly on their neighbours, and so on. A wave of compression passes down the carriage, at some speed related to how people interact with their neighbours, and that speed probably depends on how hard they were shoved by the person getting on the train. By measuring this speed, one could learn about the interactions.”
“The same is true for electrons in a quantum wire – they repel each other and cannot get past, so if one electron enters or leaves, it excites a compressive wave like the people in the train,” said the paper’s first author Dr Maria Moreno, also from the Cavendish Laboratory.
However, electrons have another characteristic, their angular momentum or ‘spin’, which also interacts with their neighbours. Spin can also set off a wave carrying energy along the wire, and this spin wave travels at a different speed to the charge wave. Measuring the wavelength of these waves as the energy is varied is called tunnelling spectroscopy. The separate spin and charge waves were detected experimentally by researchers from Harvard and Cambridge Universities.
Now, in the paper published in Nature Communications, the Cambridge researchers have gone one stage further, to test the latest predictions of what should happen at high energies, where the original theory breaks down.
A flurry of theoretical activity in the past decade has led to new predictions of other ways of exciting waves among the electrons — it’s as if the person entering the train pushes so hard some people fall over and knock into others much further down the carriage. These new ‘modes’ are weaker than the spin and charge waves and so are harder to detect.
The collaborators of the Cambridge researchers from the University of Birmingham predicted that there would be a hierarchy of modes corresponding to the variety of ways in which the interactions can affect the quantum-mechanical particles, and the weaker modes should be strongest in very short wires.
To make a set of such short wires, the Cambridge group set about devising a way of making contact to a set of 6000 narrow strips of metal that are used to create the quantum wires from the semiconducting material gallium arsenide (GaAs). This required an extra layer of metal in the shape of bridges between the strips.
By varying the magnetic field and voltage, the tunnelling from the wires to an adjacent sheet of electrons could be mapped out, and this revealed evidence for the extra curves predicted, where it can be seen as an upside-down replica of the spin curve.
These results will now be applied to better understand and control the behaviour of electrons in the building blocks of a quantum computer.
Researchers have built a record energy-efficient switch, which uses the interplay of electricity and a liquid form of light, in semiconductor microchips. The device could form the foundation of future signal processing and information technologies, making electronics even more efficient.
We’re reaching the limits of how small we can make transistors, and electronics based on liquid light could be a way of increasing the power and efficiency of the electronics we rely on.
Researchers have built a miniature electro-optical switch which can change the spin – or angular momentum – of a liquid form of light by applying electric fields to a semiconductor device a millionth of a metre in size. Their results, reported in the journal Nature Materials, demonstrate how to bridge the gap between light and electricity, which could enable the development of ever faster and smaller electronics.
There is a fundamental disparity between the way in which information is processed and transmitted by current technologies. To process information, electrical charges are moved around on semiconductor chips; and to transmit it, light flashes are sent down optical fibres. Current methods of converting between electrical and optical signals are both inefficient and slow, and researchers have been searching for ways to incorporate the two.
In order to make electronics faster and more powerful, more transistors need to be squeezed onto semiconductor chips. For the past 50 years, the number of transistors on a single chip has doubled every two years – this is known as Moore’s law. However, as chips keep getting smaller, scientists now have to deal with the quantum effects associated with individual atoms and electrons, and they are looking for alternatives to the electron as the primary carrier of information in order to keep up with Moore’s law and our thirst for faster, cheaper and more powerful electronics.
The University of Cambridge researchers, led by Professor Jeremy Baumberg from the NanoPhotonics Centre, in collaboration with researchers from Mexico and Greece, have built a switch which utilises a new state of matter called a Polariton Bose-Einstein condensate in order to mix electric and optical signals, while using miniscule amounts of energy.
Polariton Bose-Einstein condensates are generated by trapping light between mirrors spaced only a few millionths of a metre apart, and letting it interact with thin slabs of semiconductor material, creating a half-light, half-matter mixture known as a polariton.
Putting lots of polaritons in the same space can induce condensation – similar to the condensation of water droplets at high humidity – and the formation of a light-matter fluid which spins clockwise (spin-up) or anticlockwise (spin-down). By applying an electric field to this system, the researchers were able to control the spin of the condensate and switch it between up and down states. The polariton fluid emits light with clockwise or anticlockwise spin, which can be sent through optical fibres for communication, converting electrical to optical signals.
“The polariton switch unifies the best properties of electronics and optics into one tiny device that can deliver at very high speeds while using minimal amounts of power,” said the paper’s lead author Dr Alexander Dreismann from Cambridge’s Cavendish Laboratory.
“We have made a field-effect light switch that can bridge the gap between optics and electronics,” said co-author Dr Hamid Ohadi, also from the Cavendish Laboratory. “We’re reaching the limits of how small we can make transistors, and electronics based on liquid light could be a way of increasing the power and efficiency of the electronics we rely on.”
While the prototype device works at cryogenic temperatures, the researchers are developing other materials that can operate at room temperature, so that the device may be commercialised. The other key factor for the commercialisation of the device is mass production and scalability. “Since this prototype is based on well-established fabrication technology, it has the potential to be scaled up in the near future,” said study co-author Professor Pavlos Savvidis from the FORTH institute in Crete, Greece.
The team is currently exploring options for commercialising the technology as well as integrating it with the existing technology base.
As an important step towards graphene integration in silicon photonics, researchers from the Graphene Flagship have published a paper which shows how graphene can provide a simple solution for silicon photodetection in the telecommunication wavelengths.
Published in Nano Letters, this exciting research is a collaboration between the University of Cambridge (UK), The Hebrew University (Israel) and Johns Hopkins University (USA).
The mission of the Graphene Flagship is to translate graphene out of the academic laboratory, through industry and into society. This broad and ambitious aim has been at the forefront of the choices made to direct the Flagship; it focuses on real problem areas where it can make a real difference such as in Optical Communications.
Optical Communications are increasingly important because they have the potential to solve one of the biggest problems of our information age: energy consumption. Almost everything we do in everyday life consumes information and all of this information is powered by energy. If we want more and more information, we need more and more energy. In the near future, the major consumers of data traffic will be machine-to-machine communication and the Internet of Things (IoT).
To enable the IoT and the level of information it requires, current silicon photonics has a problem: it needs ten times more energy than we can provide. So, if we want this new, improved internet age, new technological, power-efficient solutions need to be found. This is why the drive to graphene-based optical communication is so important.
Over the last few years, optical communications have increased their viability over standard metal-based electronic interconnects. The current silicon-based photodetector used in optical communications has a major issue when it comes to detecting data in the near infrared range, which is the range used for telecommunications. The telecom industry has overcome this problem by integrating germanium absorbers with the standard silicon photonic devices. They have been able to make fully functioning devices on chips using this process. However, this process is complex.
In the new paper, graphene is interfaced with silicon on chip to make high responsivity Schottky barrier photodetectors. These graphene-based photodetectors achieve 0.37A/W responsivity at 1.55μm using avalanche multiplication. This high responsivity is comparable to that of the Silicon Germanium detectors currently used in silicon photonics.
Prof. Andrea Ferrari from the Cambridge Graphene Centre, who is also the Science and Technology Officer and the Chair of the Management Panel for the Graphene Flagship stated; “This is a significant result which proves that graphene can compete with the current state of the art by producing devices that can be made more simply, cheaply and work at different wavelengths. Thus paving the way for graphene integrated silicon photonics.”