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New Delhi Saturday, 20 January, 2018 - 09:00

A coffee table book on the C V Raman International Fellowship for African Researchers, highlighting the successful journey of the programme, was launched jointly by the Federation of Indian Chambers of Commerce & Industry (FICCI) and the Department of Science and Technology (DST).

The book has been brought out by the Federation of Indian Chambers of Commerce & Industry (FICCI), in partnership with the Ministry of External Affairs (MEA) and the Department of Science & Technology (DST), Government of India. The fellowship scheme was introduced under the India-Africa Forum Summit (IAFS) to promote scientific cooperation between India and Africa.

The fellowship provides opportunities for African researchers to undertake research and training spanning between 1 to 6 months at Academic and Research Institutions in India. Since its inception, close to 500 scientists and researchers from African countries have undertaken R&D work in host institution in India. The programme has helped to take the footprint of Indian science to 40 countries across Africa.

Prof. Ashutosh Sharma, Secretary, DST noted that the C V Raman International Fellowship for African Researchers was one of the most prestigious programme of DST. He has also thanked the African partner nations for their overwhelming support in making the programme a great success and strengthening the bond of partnership through scientific and technological linkages, according to a release by FICCI.

The African scholars are able to nurture their research ideas under the guidance and mentorship of leading Indian scientists and academicians and benefit from access to advanced scientific facilities in premiere educational institutes and research laboratories in India.

Welcoming the guests, Mr. Nirankar Saxena, Deputy Secretary General, FICCI said “India’s C V Raman International Fellowship programme helps build capacity of African Researchers to scale research and cull out innovations that will shape the future of Africa and India”. Dr. Arabinda Mitra, Adviser, International Cooperation, DST who instrumented the scheme said, “The C V Raman International Fellowship is a unique programme to strengthen the bonds of scientific collaboration between India and Africa through supporting human capacity building, which will enable long term partnerships in research and development”.

Around 139 R&D institutions and laboratories, universities, colleges from across 70 cities in India have hosted African researchers under this programme over the last seven years. For a majority of the Fellows, the programme has contributed immensely to their career and helped them develop new research ideas in science and technology after returning to their home country.

The scheme has got overwhelming response from pan Africa and going forward, the partners expect to raise the number of research fellows to 1000 and continue strengthening the bond by creating a bridge of knowledge between Indian research expertise and African scholars. (Research Matters)

Section: General, Science, News, Events Source:
Mumbai Friday, 19 January, 2018 - 17:03

3.6 million lives could be lost in 2050 due to air pollution, says a recent study.

According to a new study by researchers from the Indian Institute of Technology-Bombay (IIT-B), the Health Effects Institute (HEI), and the Institute for Health Metrics and Evaluation (IHME), in 2015, only one in 1000 Indians lived in areas where particulate pollution did not exceed the permissible levels prescribed by World Health Organization (WHO).

The study, titled ‘Burden of Disease Attributable to Major Air Pollution Sources in India’ is the first comprehensive assessment on fine particulate matter (PM2.5) and their impacts on human health conducted in the country at the state and national level.

The study also found that in the same year, inhabitants of 21 Indian states and six union territories were exposed to PM2.5 levels higher than those deemed safe by the Indian annual standards. PM2.5 is a kind of air pollutant that consists of fine particles with a diameter of 2.5 microns or less. These particles can be detrimental to a person’s health, as their small size ensures that they escape the body’s mechanisms for protection against aerial pollutants, and settle in the respiratory system. Long term exposure to PM2.5 can lead to serious health complications.

The biggest culprit for air-pollution related health issues in India, in 2015, was found to be household biomass burning (23.9%) and coal combustion (15.3%), which contributed to around 268,000 and 169,000 deaths respectively.  Emissions from agricultural burning, dust, transport, other diesels, and brick kilns also contributed to the burden of air pollution, which collectively contributed to 231,000 deaths in the country.

The study was greatly helped by enhanced satellite data and India’s growing network of air pollution monitors. It  builds on the data collected by prior studies, which identified air pollution as the second highest public health risk factor, after malnutrition. Based on this data, the researchers evaluated future scenarios projecting to the year 2050 to identify the key challenges faced and to highlight possible mitigation measures.

“This systematic analysis of emissions from all sources and their impact on ambient air pollution exposure found significant contributions from regional sources (like residential biomass, agricultural residue burning and industrial coal), underlying that from local sources (like transportation and brick kilns)”, said Professor Chandra Venkataraman of IIT Bombay and one of the scientists involved in the study, in a press release. If no further measures are taken to reduce air pollution, 3.6 million lives could be lost in 2050, says the study.

To overcome these challenges, the researchers of this study recommend several actions that can be taken which could also reduce the number of human deaths by 2050. The use of LPG, piped gas and other alternative fuels could lead to the elimination of biomass use. A shift from using kerosene lamps to solar or electric sources of lighting would also significantly reduce the use of biomass. The authors recommend moving away from coal based power generation, and suggest that by 2050, 75%–80% of power generation has to be non-coal to reduce air pollution.

This study is one of the many that has sounded a warning death bell on air pollution in the country. But, are we listening?

Section: General, Science, Health, Society, Policy Source: Link
Bengaluru Friday, 19 January, 2018 - 07:33

In his 1959 lecture titled ‘There’s plenty of room at the bottom’, Richard Feynman envisioned the possibilities of manipulating and controlling things on a small scale. Today controlled manipulation of nanoscale objects, whose sizes are about a billionth of a metre, is a vast area of research. Manipulation of such nanoparticles requires trapping forces that can be focused and translated precisely. In a recent study, researchers from the Indian Institute of Science, Bengaluru, have designed a novel approach to trap and manoeuvre objects as small as 100 nm.

A major problem faced with conventional trapping techniques is their inability to hold extremely small sized objects, also called cargo. Imagine picking up grains of salt using only a pair of needles! What makes it tough is that the force required to capture a particle reduces as it’s size decreases.

So far, plasmonic tweezers -- nanosized tweezers made up of noble metals -- are used to trap such small sized cargo (think of a few molecules--that is the size we are talking about!). When illuminated by light, these tweezers create a strong electromagnetic field around themselves that can attract and trap nanoparticles that are close.

However, plasmonic tweezers have a limitation. With a limited range of influence and being fixed in space, these tweezers can only capture nanoparticles in their vicinity; hence being inefficient. “So, it is necessary to design a technique that has the efficiency of a traditional plasmonic tweezer but, at the same time, is manoeuvrable”, says Souvik Ghosh, a researcher from IISc, and a co-author of this study.

In this study, published in the journal Science Robotics, Mr. Ghosh, along with Prof. Ambarish Ghosh from Centre for Nanoscience and Engineering, IISc, have designed a new class of nanotweezers, that combines plasmonic tweezers with micro robots to design ‘mobile nanotweezers’ (MNTs) that bring together the best of both world. These nanotweezers can be driven to the target objects with precise control to capture, transport and release small sized cargo made of various materials with high speed and efficiency. "Microbots can carry/push objects very quickly, but do not work well for sub-micron objects. By combining the functions of these two technologies, we can not only trap but move very small objects very quickly" adds Mr. Ghosh.

The design of these mobile nanotweezers is inspired by microorganisms. Akin to a bacterium that moves by rotating its helical flagellum -- a cellular protrusion used for swimming -- these ferromagnetic, helical nanostructures can be moved by a uniform, rotating magnetic field, which moves and rotates along the direction of the magnetic field. By controlling the magnetic field, the motion of the nanotweezers can be controlled.

The researchers have designed two similar MNTs made of silicon dioxide. Silver and iron, combined with the nanostructures, provide plasmonic properties and magnetic properties. While the first design contains silver nanoparticles distributed across its surface, alternating layers of silver and iron are combined within the structure of the second.

The researchers tested the two designs in a fluid chamber containing some cargo particles. They magnetically steered the nanotweezers towards the cargo and when the chamber was illuminated, they observed that the nanotweezer trapped the cargo which was subsequently maneuvered and released by decreasing the illumination intensity. “The first design works very well for particles that accumulate near hot places like silica particles, while the second is very general and does not care whether the particles like heat or not. For a general application, the second design is preferred”, says Mr. Ghosh.

In addition, the researchers observed that when two particles of different sizes are present in the cargo, by decreasing the illumination, the smaller particle can be released, whereas increasing the frequency of the rotating magnetic field would release the larger particle. This unique sorting behaviour allows the transport of nanoparticles of different sizes by simply varying the two influences.

The researchers also tested their devices beyond plastic and glass particles. They successfully trapped and transported Staphylococcus aureus bacteria and subsequently released it by turning the illumination off. Illumination intensities required by these nanotweezers are almost two orders lower than that can damage living bacteria. Also fluorescent nanodiamonds, an excellent candidate for quantum sensing, was maneuvered using the MNTs.

“From being able to carry live bacteria to placing very small objects such as nanodiamonds and quantum dots at specific positions on a device, their applications could range from biomedicine to quantum technologies, sensor devices and many more”, Prof. A. Ghosh explains to Research Matters.

Apart from carrying small objects to various spots of a microfluidic device, the researchers can also localize them with high spatial resolution and then take them away if necessary. “This should open up new avenues in nanoscale assembly that did not exist before" adds Prof. Ghosh.

What comes next in this ‘small’ journey? “We are working on parallelizing the nanotweezers so that a collection of them can sort and assemble at nanoscale, just like a group of robots would work in an industrial assembly line. This will allow us to scale up our technology and will surely have tremendous commercial impact”, signs off Prof. Ghosh.

Section: General, Science, Technology, Deep-dive Source:
Bengaluru Thursday, 18 January, 2018 - 14:50

The Indian Institute of Science (IISc) proudly presents Pravega-- an annual science and cultural festival organized by the institute’s undergraduate community. The event will be held from 19 to 21 January, 2018.

This year, Pravega promises to have a little something for everyone, with a wide variety of events in diverse fields being conducted throughout the three days. For the science aficionados, there are more technical events than ever, with plenty of events like Decoherence and Hackathon being held on a national level.

The flagship event, Pravega Innovation Summit (PIS), is an unprecedented venture to bring about widespread collaboration between researchers and investors. This year will see many workshops in diverse fields, ranging from cyber security to automobile engines. The title sponsor Airbus, will also conduct a workshop for underprivileged children, to help them realize their dreams in the future.

To keep everyone entertained, the fest will feature many fun events and games, both technical and non-technical, which will be free to participate and play in. Pravega is also famous for being graced with renowned celebrities who entertain the audience, and this year promises to be the same with the well-known band Thaikkudam Bridge headlining the Pronites.

The general registrations for Pravega, as well as the Pronite registrations are free, and all are encouraged to visit the campus and satisfy their wanderlust. Details of registration can be found on pravega.org

Don’t want to participate in any events? Not a problem! Even non-participants will have plenty to catch their attention, with the cultural events and the beautiful campus to occupy their attention. Visit IISc and be a part of Pravega to experience an exquisite blend of scientific innovation and cultural delights.

Section: General, Events Source: Link
Bengaluru Thursday, 18 January, 2018 - 13:50

Prasad Raghavendra, Associate Professor of electrical engineering and computer science at the University of California, Berkeley, and David Steurer, professor of theoretical computer science at ETH Zurich have been chosen as the winners of the first Michael and Sheila Held prize. They were chosen “for a body of work which revolutionizes our understanding of optimization and complexity in computer science” announces a press release from the academy.

The duo will be awarded a cash prize of $ 100,000 during the Academy’s 155th annual meeting to be held on 29 April 2018.

Raghavendra and Steurer work on computational complexity--problems that are classified as hard and considered impossible for a computer to completely solve within a reasonable time frame. Their work helps determine if a computer can find an approximate solution to such problems. The duo showed that compared to other algorithms, semidefinite programming (SDP)—a type of optimization of complexity problems, gives the best possible approximation for several of the hard optimization problems. According to the press release from the academy,“the awardees have advanced a theoretical framework for SDP, which has led to new algorithms and a deeper understanding of SDP’s limitations.”

The Michael and Sheila Held prize presented for the first time this year, will be awarded annually to ‘honour outstanding, innovative, creative, and influential research in the areas of combinatorial and discrete optimization, or related parts of computer science, such as the design and analysis of algorithms and complexity theory’. The prize was established in 2017 by the bequest of Michael and Sheila Held.

The National Academy of Sciences (NAS) is a private, non-profit society of distinguished scholars, based in USA. The scientists are elected by their peers to membership in the NAS for outstanding contributions to research. The NAS, along with the National Academy of Engineering and National Academy of Medicine --provides science, technology, and health policy advice to the federal government and other organizations.

Section: General, Science, Events Source: Link
Bengaluru Thursday, 18 January, 2018 - 07:35

Climate change has always been a major driver that has shaped our planet’s biodiversity. Massive extinctions and severe adaptations are all a result of climate change. As we start to understand how the current change in climate is impacting us, effects of previous climate changes are hardly understood. In a rare study combining biology and paleontology, researchers from the Indian Institute of Science, Bengaluru, have shown how different climatic factors, present millions of years ago, have influenced the evolution of fan-throated lizards.

Fan-throated lizards (FTL) is a kind of agama found in India. Males of this species have an extendable dewlap or fan which is brightly coloured in some species. Until a few years ago, researchers thought that a single species of the genus Sitana, was present throughout the country. However, with increased efforts, 10 more species of Sitana and three more species of a new genus Sarada, were found over time. The study attributes this observed diversity to the onset of monsoon and subsequent aridification during the Miocene epoch--a geological period spanning from 23 million to 5.3 million years ago.

“In 2007, I saw some photographs of Sitana ponticeriana (fan-throated lizards) from Maharashtra that looked very different from those in Pondicherry. This was the first time when I got interested to study this group”, says Dr V. Deepak, the lead author of the study published in the journal Molecular Phylogenetics and Evolution. “These preliminary observations gave me the hint about the diversity within these lizards”, he recounts.

The researchers used genetic data of fan-throated lizards sampled from different regions where they were found. They then used tools to tell apart two or more distinct species tagged as a single species due to similarities in their looks and body characteristics. In their molecular dating they used five fossils and sequences of the different Fan-throated lizard species trying to understand the time at which different diversifications were observed.

“Molecular dating is a very useful tool if one understands the underlying principles. Typically, biologists rely on the information provided by paleontologists about the fossils. When paleontologists describe a fossil, they also estimate its age and the error associated with this number. Based on the morphological description of the fossil, paleontologists and neontologists (those who study living organisms as opposed to fossils) identify to which extant group (genus, family, subfamily) the fossils are related to. Given this information, a particular fossil can be placed in the molecular phylogeny to estimate the dates for the related species group of our interest”, informs Dr. Deepak about the methods used in this study.

In total, the team identified 15 species of fan-throated lizards, and discovered five potential new species of Sitana, and one new species of Sarada. They also found that the dry zone species of the Sarada-Sitana group diverged from the Sri Lankan wet zone sister genus Otocryptis at around 26 million years ago during early Miocene. Sitana and Sarada evolved as separate genera around 18 million years ago during mid-Miocene, which corresponds to the establishment of monsoon. During the late Miocene, around 11 million years ago, there was an increase in open habitats and a decline in rainforest habitats, with the initiation of aridification in South Asia. This helped Sarada and Sitana to further diversify into the present delimited species.

Also, 13 of the 15 delimited species were found from peninsular India. This greater diversity of fan throated lizards in peninsular India could be due to the availability of different types of habitat, compared to other relatively homogeneous dry zones of the subcontinent. Hence, climatic factors and landscape heterogeneity were found to have influenced current diversification  in this group.

The study has brought the evolutionary and conservation significance of the Indian arid zone, where lizard diversity is underestimated, to focus. Systematic documentation of lizards in this area is necessary, say the researchers. “I advocate taxonomy of different lizard species to be dealt with caution. One has to look at more than just traditional characters used in lizard systematics, examine as many museum specimens as possible before going out in the field. Zoological Survey of India has one of the oldest and widest arrays of collections in the country and this needs to be utilized”, recommends Dr. Deepak.

As we have entered Anthropocene, a human-influenced epoch, human-induced climate change has already started to take its toll on biodiversity. What does it mean for the fan-throated lizards? “These lizards are short-lived species with 1-2 years of lifespan. They typically breed just before monsoon when the habitats are dry and are more visible when they display and mate. After the breeding season that lasts up to 3 months, the females lay their eggs with 40 to 45 days of incubation period. This period roughly corresponds to the post-monsoon season when the young ones emerge. There is sufficient vegetation for them to hide and surplus insects to feed on. Therefore, the life cycle of these lizards is synchronized with the trends in current climatic conditions. If there is continuous disruption of the climatic cycle due to climate change it will indeed affect the long-term survival of many of the these species, particularly the range restricted species”, signs off Dr. Deepak.

Section: General, Science, Deep-dive Source:
Bengaluru Wednesday, 17 January, 2018 - 15:00

As conventional memory devices like the hard drives and flash drives, generally made of semiconductor materials reaching limit in terms of their size and storage capacity a new emerging technology- Resistive Random Access Memory (RRAM)- holds the promise of cheaper and efficient replacement to existing technologies. 

Researchers at Indian Institute of Technology (IIT), Hyderabad have now studied the effect of a magnetic field on the behavior of an RRAM, to enable remote control of RRAMs, without any physical connections to the device.

RRAM is a type of non-volatile Random Access Memory (RAM) which means the data on the memory device is not wiped out once the power to the device is turned off. Hard drives on a computer, flash drives, and memory cards in a phone are all types of non-volatile memory devices. The RAM on a computer and smartphones, on the other hand, is a volatile memory device, meaning the data on the device gets cleared every time the device is shut down.

RRAMs work is based on a phenomenon called resistive switching, wherein data is stored on the device by switching between a high resistance state (HRS) and a low resistance state (LRS) to store the 0s and 1s, the two components of a binary language which computers use to communicate. The switching between HRS and LRS is controlled using a voltage applied to the device.

In their new study, the researchers studied the effect of a magnetic field on the resistive switching ability of an RRAM made of Silver/ Titanium Dioxide/Fluorine doped Tin oxide (Ag/TiO2/FTO). The study revealed an ability to control the resistance switching on such an RRAM, by varying an applied magnetic field. The researchers have hypothesized that Lorentz force, a force arising due to the presence of electric and magnetic fields may be playing a significant role in switching the resistance states.

Conventional RRAMs achieve resistance switching by varying the voltage applied to the device, which requires a physical connection to the device. Using magnetic fields to alter the resistance states allows a remote switching of the resistance states, without the need for a physical connection. The researchers believe that the present study would be useful in designing RRAM devices that could be operated with a magnetic field, increasing their efficiency.

Section: General, Science, Technology Source:
Bengaluru Wednesday, 17 January, 2018 - 11:06

Cancer, a dreaded disease, has been on a rampant spread over the past decade. Reports from the Indian Council of Medical Research (ICMR) estimated 14.5 lakh new cancer cases in 2016, and this number is likely to go up to 17.3 lakhs in 2020. Scientists around the world are uncovering new facets of this disease in a bid to understand its many faces and design the best and the most effective drugs against it. So far, we know that abnormal and uncontrollable growth of cells in our body leads to cancer. In advanced stages, these cancerous cells spread to different parts of the body through our blood or lymph, in a process called metastasis. In a new study, researchers from the Indian Institute of Science, Bengaluru, led by Prof. Annapoorni Rangarajan, have made some astounding discoveries on the molecular mechanism behind the spread of cancer, which can help better understand and treat the disease.

But how exactly does metastasis happen? Cancerous cells from a tumour, called ‘circulating tumour cells’ or CTCs, enter the bloodstream or the lymph system and move throughout the body. With the help of proteins called integrins, these tumour cells adhere to the extracellular matrix – a collection of molecules that support the cell structure. Once they find a suitable place, they thrive and develop into another cancerous tumour. However, if these tumour cells are deprived of the matrix, they die a form of programmed cell death called anoikis. For cancer to thrive, the tumour cells must develop resistance to anoikis. But how do they develop resistance? That is what the researchers of this study have uncovered.

The scientists studied the roles of Akt – an enzyme that regulates the process of survival and metabolism in a cell, and AMP activated protein kinase (AMPK) – an enzyme that promotes the breakdown of complex molecules into simpler ones for the cell to utilise. They used human breast cancer cells and mice for the study. While Akt drives cell growth and multiplication, thus promoting tumor growth, AMPK was long thought of as a tumor suppressor because of its growth retarding effects. But, recent studies have shed light on how AMPK could also aid tumour growth, as it helps the cell survive when it is in need of energy or in an environment of reduced oxygen.

“It was about ten years ago, when a graduate student in the lab, Sravanth, made the first observation that AMPK is activated upon matrix-detachment”, reveals Prof. Rangarajan about the motivation behind this study. This surprising observation made the team question the role of AMPK in resisting anoikis, while most of the studies until then had always credited Akt for this phenomenon. “We were inquisitive to check the status of Akt in detached cells, and to our surprise, we found that Akt is markedly inactivated in detached cells”, she adds.

The researchers of the study observed that AMPK is activated in detached cells compared to adherent cells, whereas Akt is more activate in adherent cells compared to detached. When tumor cells detach from their primary site, they are marked for death. This is because they are anchorage-dependent cells and need to be attached to the extracellular matrix to grow and divide. When detached, they trigger the enzyme AMPK, which represses the enzyme Akt by a protein called PHLPP2. When the tumour cells re-attach to the matrix, the Akt enzyme is triggered. This represses AMPK via another protein called PP2Cα, therefore showing a double negative feedback loop that helps the tumor cells to adapt to matrix deprivation.

“Our study suggests that AMPK inhibition will help prevent cancer spread by metastasis. Currently, metformin, a first line anti-diabetic drug that ironically activates AMPK is being trialled in cancer treatment. Our study raises concerns on the use of AMPK-modulating agents before further detailed investigations. A side effect of metformin might actually promote cancer spread in some cases”, says Prof. Rangarajan about the study.

This study provides newer insights into developing AMPK and PHLPP2 inhibitors as potential drugs against cancer that can target the molecular mechanisms involved in the spread of cancer. As a next step, the researchers are pursuing studies to understand this complex mechanism better. “We have showed that AMPK activation upregulates the phosphatase PHLPP2 to inhibit Akt. However, the mechanism(s) by which AMPK does this is not known. We are currently pursuing this”, says Prof. Rangarajan, before signing off.
 

Section: General, Science, Health, Deep-dive Source:
Bengaluru Wednesday, 17 January, 2018 - 07:40

This has been taken down since it was brought to the notice of the Editorial team that the journal in which the study was published is listed as a predatory journal. The Editorial team regrets this error in judgement.

Section: General, Science, Ecology, Society, Policy Source:
Bengaluru Tuesday, 16 January, 2018 - 10:36

All of modern electronic devices work with binary language of just zeroes and ones. Transistors--tiny switches employed in most of these gadgets--play a crucial role in these devices. Over the years, transistors have gone from the size of a small phone, to millions of them fitting in a smartphone! They are ubiquitous and improving their form and performance is an active area of research. Now, scientists from the Indian Institute of Science (IISc) have designed a novel transistor by combining two different types of transistors in to one.

The functioning of a typical transistor is analogous to a dam. There is a ‘source’ from where the water, or in this case, electrons are generated, and a ‘drain’ where the electrons flow into. A gate controls the flow of these electrons between the source and drain. When the gate is closed, a barrier is presented to the electrons and their flow is blocked. When a small voltage is applied to the gate, the height of the barrier reduces, allowing the electrons to hop across, causing a current to flow between the source and the drain. Lesser the amount of voltage required to open the gate, more efficient the transistor becomes.

“The transistor is a gate controlled switch, where the voltage value on the gate decides whether the switch is ‘on’ or ‘off’. For example, in modern transistors, when you apply 1 Volt to the gate, the transistor is turned ‘on’ and when you apply 0 V to the gate, the transistor is turned ‘off’. For an ideal switch, you need large ‘on’ current and ideally zero ‘off’ current. But, all transistors used in today's electronics have a non-zero ‘off’ current, the value of which depends on the ‘subthreshold swing’”, explains Prof. Navakanta Bhat, Chairman of the Centre for Nano Science and Engineering at IISc, and a co-author of the study.

The ‘subthreshold swing’ is the minimum voltage required for opening or closing the gate. Much like the dam, opening or closing the gates requires a minimum amount of energy to do so. “Steeper the subthreshold swing, or lower its value, the faster will be the fall of current and hence, lower will be the ‘off’ current for a given value of ‘on’ current,” remarks Prof. Bhat. The efficiency of such transistors, commonly called thermionic transistors, depend on the amount of voltage required to activate the gate. Thus, in the present the efficiency of such transistors has hit a fundamental bottleneck, since no matter how small they get, the required gate voltage remains fairly large.

“In the today's thermionic transistors, the best (i.e. minimum) value of subthreshold swing is 60mV/decade. In order to produce a ‘on’ current, the electrons from the source of the transistor have to overcome the energy barrier (controlled by the gate) and then go to the drain. Only those electrons that have energy more than the barrier height can contribute to the current. The energy distribution is governed by Boltzmann statistics and hence the limit of 60mV/decade”, explains Shubhadeep Bhattacharjee, a PhD student at CeNSE, who is also one of the researchers in this study.

Researchers over came this bottleneck with another type of transistors called tunnel field effect transistors (tunnel-FET). This type of transistors use a fundamental property of quantum particles, like electrons, called tunneling. According to Shubhadeep, “with this new method of transport (tunneling), the electrons need not attain energies higher than the barrier. Even if the energy is lower than the barrier height, they can ‘tunnel’ through the barrier, provided the tunneling distance controlled by gate is small. Hence we are no longer limited by Boltzmann statistics.” Thus tunnel FETs can increase the efficiency of transistors by decreasing the amount of gate voltage that is required.

However, tunnel FETs too have their own disadvantages, as the amount of current that flow between the source and the drain is very low compared to their thermionic counterparts. To overcome the shortcoming of both these technologies, the researchers of this study built a new device which combines the functioning of both thermionic and tunneling components into one transistor. To achieve this, the scientists used two gates, which could be controlled independently, in a single transistor, along with a new switching element – tunable Schottky barrier, a type of energy barrier to electrons formed at a metal-semiconductor junction.

The new hybrid device can switch between a conventional thermionic transistor and a modern tunnelling transistor, thus providing the benefits of both worlds, with very little of the disadvantages. “By having an independent control of the tunnel barrier height and the tunnel barrier width, we can combine both tunneling and thermionic components in single transistor”, remarks Shubhadeep. The new transistor also consumes much less power than the thermionic ones, and can produce much higher currents than many modern tunnelling transistors.

So where could these new transistors find their applications? “This work will open up the possibility of using new kind of transistor for building future electronic circuits that will have ultra-low power consumption. For instance, a smart watch a few years down the line, could potentially use transistors like this, and provide performance which is far superior compared to the state of the art smart phones available today”, says Prof. Bhat. The union of the transistors has really made the future of electronics exciting! 

Section: General, Science, Technology Source:

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