MIT: Making renewable power more viable for the grid


Making renewable power more viable for the grid

“Air-breathing” battery can store electricity for months, for about a fifth the cost of current technologies.

Wind and solar power are increasingly popular sources for renewable energy. But intermittency issues keep them from connecting widely to the U.S. grid: They require energy-storage systems that, at the cheapest, run about $100 per kilowatt hour and function only in certain locations.

Now MIT researchers have developed an “air-breathing” battery that could store electricity for very long durations for about one-fifth the cost of current technologies, with minimal location restraints and zero emissions. The battery could be used to make sporadic renewable power a more reliable source of electricity for the grid.

For its anode, the rechargeable flow battery uses cheap, abundant sulfur dissolved in water. An aerated liquid salt solution in the cathode continuously takes in and releases oxygen that balances charge as ions shuttle between the electrodes. Oxygen flowing into the cathode causes the anode to discharge electrons to an external circuit. Oxygen flowing out sends electrons back to the anode, recharging the battery.

“This battery literally inhales and exhales air, but it doesn’t exhale carbon dioxide, like humans — it exhales oxygen,” says Yet-Ming Chiang, the Kyocera Professor of Materials Science and Engineering at MIT and co-author of a paper describing the battery.

The research appears today in the journal Joule.

The battery’s total chemical cost — the combined price of the cathode, anode, and electrolyte materials — is about 1/30th the cost of competing batteries, such as lithium-ion batteries. Scaled-up systems could be used to store electricity from wind or solar power, for multiple days to entire seasons, for about $20 to $30 per kilowatt hour.

Co-authors with Chiang on the paper are: first author Zheng Li, who was a postdoc at MIT during the research and is now a professor at Virginia Tech; Fikile R. Brushett, the Raymond A. and Helen E. St. Laurent Career Development Professor of Chemical Engineering; research scientist Liang Su; graduate students Menghsuan Pan and Kai Xiang; and undergraduate students Andres Badel, Joseph M. Valle, and Stephanie L. Eiler.

Finding the right balance

Development of the battery began in 2012, when Chiang joined the Department of Energy’s Joint Center for Energy Storage Research, a five-year project that brought together about 180 researchers to collaborate on energy-saving technologies. Chiang, for his part, focused on developing an efficient battery that could reduce the cost of grid-scale energy storage.

A major issue with batteries over the past several decades, Chiang says, has been a focus on synthesizing materials that offer greater energy density but are very expensive. The most widely used materials in lithium-ion batteries for cellphones, for instance, have a cost of about $100 for each kilowatt hour of energy stored.

“This meant maybe we weren’t focusing on the right thing, with an ever-increasing chemical cost in pursuit of high energy-density,” Chiang says. He brought the issue to other MIT researchers. “We said, ‘If we want energy storage at the terawatt scale, we have to use truly abundant materials.’”

The researchers first decided the anode needed to be sulfur, a widely available byproduct of natural gas and petroleum refining that’s very energy dense, having the lowest cost per stored charge next to water and air. The challenge then was finding an inexpensive liquid cathode material that remained stable while producing a meaningful charge.

That seemed improbable — until a serendipitous discovery in the lab.

On a short list of candidates was a compound called potassium permanganate. If used as a cathode material, that compound is “reduced” — a reaction that draws ions from the anode to the cathode, discharging electricity. However, the reduction of the permanganate is normally impossible to reverse, meaning the battery wouldn’t be rechargeable.

Still, Li tried. As expected, the reversal failed. However, the battery was, in fact, recharging, due to an unexpected oxygen reaction in the cathode, which was running entirely on air. “I said, ‘Wait, you figured out a rechargeable chemistry using sulfur that does not require a cathode compound?’ That was the ah-ha moment,” Chiang says.

Using that concept, the team of researchers created a type of flow battery, where electrolytes are continuously pumped through electrodes and travel through a reaction cell to create charge or discharge.

The battery consists of a liquid anode (anolyte) of polysulfide that contains lithium or sodium ions, and a liquid cathode (catholyte) that consists of an oxygenated dissolved salt, separated by a membrane.

Upon discharging, the anolyte releases electrons into an external circuit and the lithium or sodium ions travel to the cathode.

At the same time, to maintain electroneutrality, the catholyte draws in oxygen, creating negatively charged hydroxide ions. When charging, the process is simply reversed. Oxygen is expelled from the catholyte, increasing hydrogen ions, which donate electrons back to the anolyte through the external circuit.

“What this does is create a charge balance by taking oxygen in and out of the system,” Chiang says.

Because the battery uses ultra-low-cost materials, its chemical cost is one of the lowest — if not the lowest — of any rechargeable battery to enable cost-effective long-duration discharge. Its energy density is slightly lower than today’s lithium-ion batteries.

“It’s a creative and interesting new concept that could potentially be an ultra-low-cost solution for grid storage,” says Venkat Viswanathan, an assistant professor of mechanical engineering at Carnegie Mellon University who studies energy-storage systems.

Lithium-sulfur and lithium-air batteries — where sulfur or oxygen are used in the cathode — exist today. But the key innovation of the MIT research, Viswanathan says, is combining the two concepts to create a lower-cost battery with comparable efficiency and energy density. The design could inspire new work in the field, he adds: “It’s something that immediately captures your imagination.”

Making renewables more reliable

The prototype is currently about the size of a coffee cup. But flow batteries are highly scalable, Chiang says, and cells can be combined into larger systems.

As the battery can discharge over months, the best use may be for storing electricity from notoriously unpredictable wind and solar power sources. “The intermittency for solar is daily, but for wind it’s longer-scale intermittency and not so predictable.

When it’s not so predictable you need more reserve — the capability to discharge a battery over a longer period of time — because you don’t know when the wind is going to come back next,” Chiang says. Seasonal storage is important too, he adds, especially with increasing distance north of the equator, where the amount of sunlight varies more widely from summer to winter.

Chiang says this could be the first technology to compete, in cost and energy density, with pumped hydroelectric storage systems, which provide most of the energy storage for renewables around the world but are very restricted by location.

“The energy density of a flow battery like this is more than 500 times higher than pumped hydroelectric storage. It’s also so much more compact, so that you can imagine putting it anywhere you have renewable generation,” Chiang says.

The research was supported by the Department of Energy.

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MIT: Researchers Develop Nanoparticles that Deliver the CRISPR genome-editing system – Big Step Forward for Cancer Research


In a new study, MIT researchers have developed nanoparticles that can deliver the CRISPR genome-editing system and specifically modify genes in mice.

The team used nanoparticles to carry the CRISPR components, eliminating the need to use viruses for delivery.

Using the new delivery technique, the researchers were able to cut out certain genes in about 80 percent of liver cells, the best success rate ever achieved with CRISPR in adult animals.

“What’s really exciting here is that we’ve shown you can make a nanoparticle that can be used to permanently and specifically edit the DNA in the liver of an adult animal,” says Daniel Anderson, an associate professor in MIT’s Department of Chemical Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES).

One of the genes targeted in this study, known as Pcsk9, regulates cholesterol levels. Mutations in the human version of the gene are associated with a rare disorder called dominant familial hypercholesterolemia, and the FDA recently approved two antibody drugs that inhibit Pcsk9.

However these antibodies need to be taken regularly, and for the rest of the patient’s life, to provide therapy. The new nanoparticles permanently edit the gene following a single treatment, and the technique also offers promise for treating other liver disorders, according to the MIT team.

Anderson is the senior author of the study, which appears in the Nov. 13 issue of Nature Biotechnology. The paper’s lead author is Koch Institute research scientist Hao Yin.

Other authors include David H. Koch Institute Professor Robert Langer of MIT, professors Victor Koteliansky and Timofei Zatsepin of the Skolkovo Institute of Science and Technology, and Professor Wen Xue of the University of Massachusetts Medical School.

Targeting Disease

Many scientists are trying to develop safe and efficient ways to deliver the components needed for CRISPR, which consists of a DNA-cutting enzyme called Cas9 and a short RNA that guides the enzyme to a specific area of the genome, directing Cas9 where to make its cut.

In most cases, researchers rely on viruses to carry the gene for Cas9, as well as the RNA guide strand. In 2014, Anderson, Yin, and their colleagues developed a nonviral delivery system in the first-ever demonstration of curing a disease (the liver disorder tyrosinemia) with CRISPR in an adult animal. However, this type of delivery requires a high-pressure injection, a method that can also cause some damage to the liver.

Later, the researchers showed they could deliver the components without the high-pressure injection by packaging messenger RNA (mRNA) encoding Cas9 into a nanoparticle instead of a virus. Using this approach, in which the guide RNA was still delivered by a virus, the researchers were able to edit the target gene in about 6 percent of hepatocytes, which is enough to treat tyrosinemia.

While that delivery technique holds promise, in some situations it would be better to have a completely nonviral delivery system, Anderson says.

One consideration is that once a particular virus is used, the patient will develop antibodies to it, so it couldn’t be used again.

Also, some patients have pre-existing antibodies to the viruses being tested as CRISPR delivery vehicles.

In the new Nature Biotechnology paper, the researchers came up with a system that delivers both Cas9 and the RNA guide using nanoparticles, with no need for viruses.

To deliver the guide RNAs, they first had to chemically modify the RNA to protect it from enzymes in the body that would normally break it down before it could reach its destination.

The researchers analyzed the structure of the complex formed by Cas9 and the RNA guide, or sgRNA, to figure out which sections of the guide RNA strand could be chemically modified without interfering with the binding of the two molecules. Based on this analysis, they created and tested many possible combinations of modifications.

“We used the structure of the Cas9 and sgRNA complex as a guide and did tests to figure out we can modify as much as 70 percent of the guide RNA,” Yin says. “We could heavily modify it and not affect the binding of sgRNA and Cas9, and this enhanced modification really enhances activity.”

Reprogramming the Liver

The researchers packaged these modified RNA guides (which they call enhanced sgRNA) into lipid nanoparticles, which they had previously used to deliver other types of RNA to the liver, and injected them into mice along with nanoparticles containing mRNA that encodes Cas9.

They experimented with knocking out a few different genes expressed by hepatocytes, but focused most of their attention on the cholesterol-regulating Pcsk9 gene. The researchers were able to eliminate this gene in more than 80 percent of liver cells, and the Pcsk9 protein was undetectable in these mice. They also found a 35 percent drop in the total cholesterol levels of the treated mice.

The researchers are now working on identifying other liver diseases that might benefit from this approach, and advancing these approaches toward use in patients.

“I think having a fully synthetic nanoparticle that can specifically turn genes off could be a powerful tool not just for Pcsk9 but for other diseases as well,” Anderson says.

“The liver is a really important organ and also is a source of disease for many people. If you can reprogram the DNA of your liver while you’re still using it, we think there are many diseases that could be addressed.”

“We are very excited to see this new application of nanotechnology open new avenues for gene editing,” Langer adds.

Materials provided by MIT News.Note: Content may be edited for style and length. 

Why This New Quantum Computing Startup Has a Real Shot at Beating Its Competition


A startup called Quantum Circuits plans to compete with the likes of IBM, Google, Microsoft, and Intel to bring quantum computing out of the lab and into the wider world.

There’s one good reason to think it might be able to beat them all.

That’s because Quantum Circuits was founded by Robert Schoelkopf, a professor at Yale, whose work in many ways has helped kick-start this exciting new era of quantum advances.

Quantum computers exploit two strange features of quantum physics, entanglement and superposition, to process information in a fundamentally different way from traditional computers.

The approach allows the power of such machines to scale dramatically with even just a few quantum bits, or qubits. Those racing to build practical quantum computers are nearing the point where quantum machines will be capable of doing things that no conventional machine could—an inflection point known as quantum supremacy.

The promise of reaching such a milestone has transformed the field from a mostly academic endeavor into a high-stakes competition between the research arms of several big companies and a few startups. And everyone is using the superconducting circuits Schoelkopf pioneered.

He and colleagues were the first to create a “quantum bus” for entangling qubits using wires, as well as the first to demonstrate quantum algorithms and error correction techniques for quantum circuits.

Quantum Circuits’s other two founders are Michel Devoret, a professor of applied physics at Yale, and Luigi Frunzio, a research scientist in Schoelkopf’s lab (all three are in the photo above, with Frunzio, Schoelkopf, and Devoret starting from left).

“No team has done more to pioneer the superconducting approach,” Isaac Chuang, an MIT professor working on quantum computing and an advisor to the company, said in a release issued by Yale. “[The people behind Quantum Circuits] are responsible for a majority of the breakthroughs in solid-state quantum computing in the past decade.”

SOURCE: YALE UNIVERSIT

The Fuel Tank of Tomorrow – A Super Capacitor? +YouTube Video


KiloWatt Labs CEO Omer Ghani explains in the above interview, filmed at the IDTechEX Show!, that his company has overcome these challenges and has begun shipping large-scale, super capacitor-based energy storage solutions for applications such as microgrid, renewable, utility and mobility. He indicates their solution is a cost-competitive replacement for traditional battery approaches,

Read more at: http://www.viodi.tv/2016/12/09/the-fu…

Fisker Claims New Graphene Based Battery Breakthrough – 500 Mile Range and ONE Minute Charging!


When Henrik Fisker relaunched its electric car startup last year, he announced that their first car will be powered by a new graphene-based hybrid supercapacitor technology, but he later announced that they put those plans on the backburner and instead will use more traditional li-ion batteries.

Now the company is announcing a “breakthrough” in solid-state batteries to power their next-generation electric cars and they are filing for patents to protect their IP.

Get ready for some crazy claims here.

Solid-state batteries are thought to be a lot safer than common li-ion cells and could have more potential for higher energy density, but they also have limitations, like temperature ranges, electrode current density, and we have yet to see a company capable of producing it in large-scale and at an attractive price point competitive with li-ion.

Now Fisker announced that they are patenting a new solid-state electrode structure that would enable a viable battery with some unbelievable specs.

Here’s what they claim (via GreenCarCongress):

“Fisker’s solid-state batteries will feature three-dimensional electrodes with 2.5 times the energy density of lithium-ion batteries. Fisker claims that this technology will enable ranges of more than 500 miles on a single charge and charging times as low as one minute—faster than filling up a gas tank.”

Here’s a representation of the three-dimensional electrodes:

Fisker has been all over the place with its new Emotion electric car and we have highlighted that in our look at Fisker’s unbelievable claims.

But its latest solid-state project is led by Dr. Fabio Albano, VP of battery systems at Fisker and the co-founder of Sakti3, which adds credibility to the effort.

Albano commented on the announcement:

“This breakthrough marks the beginning of a new era in solid-state materials and manufacturing technologies. We are addressing all of the hurdles that solid-state batteries have encountered on the path to commercialization, such as performance in cold temperatures; the use of low cost and scalable manufacturing methods; and the ability to form bulk solid-state electrodes with significant thickness and high active material loadings. We are excited to build on this foundation and move the needle in energy storage.”

Electrek’s Take

Like any battery breakthrough announcement, it should be taken with a grain of salt. Most of those announcements never result in any kind of commercialization.

For this particular technology, Fisker says that it will be automotive production grade ready around 2023.

A lot of things can happen over the next 5 years.

In the meantime, Fisker plans to launch its Emotion electric car at CES 2018 in just 2 months. Fisker already unveiled a prototype of the new electric car and started taking pre-orders this summer.

Graphene water filter turns whisky clear – How Can Graphene Help Desalination? +Video


graphenewateCredit: University of Manchester

Previously graphene-oxide membranes were shown to be completely impermeable to all solvents except for water. However, a study published in Nature Materials, now shows that we can tailor the molecules that pass through these membranes by simply making them ultrathin.

The research team led by Professor Rahul Nair at the National Graphene Institute and School of Chemical Engineering and Analytical Science at The University of Manchester tailored this membrane to allow all solvents to pass through but without compromising it’s ability to sieve out the smallest of particles.

In the newly developed ultrathin membranes, graphene-oxide sheets are assembled in such a way that pinholes formed during the assembly are interconnected by graphene nanochannels, which produces an atomic-scale sieve allowing the large flow of solvents through the membrane.

This new research allows for expansion in the applications of graphene based membranes from sea  desalination to organic  nanofiltration (OSN). Unlike sea water desalination, which separate salts from water, OSN technology separates charged or uncharged organic compounds from an organic solvent.

As an example, Manchester scientists demonstrated that graphene-oxide membranes can be designed to completely remove various organic dyes as small as a nanometre dissolved in methanol.

Graphene water filter turns whisky clear
Credit: University of Manchester

Prof. Nair said, “Just for a fun, we even filtered whisky and cognac through the graphene-oxide membrane. The membrane allowed the alcohol to pass through but removed the larger molecules, which gives the amber colour. The clear whisky smells similar to the original whisky but we are not allowed to drink it in the lab, however it was a funny Friday night experiment!”

The newly developed membranes not only filter out small molecules but it boosts the filtration efficiency by increasing the solvent flow rate.

Prof. Nair added “Chemical separation is all about energy, various chemical separation processes consume about half of industrial energy useage. Any new efficient separation process will minimize the consumption of energy, which is in high demand now. By 2030, the world is projected to consume 60% more energy than today.”

Dr. Su, who led the experiment added “The developed membranes are not only useful for filtering alcohol, but the precise sieve size and high flux open new opportunity to separate molecules from different organic solvents for chemical and pharmaceutical industries. This development is particularly important because most of the existing polymer-based membranes are unstable in organic solvents whereas the developed graphene-oxide  is highly stable.”

How Can Graphene Help Desalination?

 

Graphene-oxide membranes developed at the National Graphene Institute have attracted widespread attention for water filtration and desalination applications, providing a potential solution to the water scarcity.

By using ultra-thin membranes, this is the first clear-cut experiment to show how other solvents can be filtered out, proving that there is potential for organic solvent nanofiltration.

Graphene- the world’s first two-dimensional material is known for its versatile superlatives, it can be both hydrophobic and hydrophilic, stronger than steel, flexible, bendable and one million times thinner than a human hair.

This research has changed the perception of what graphene-oxide membranes are capable of and how we can use them. By being able to design these membranes to filter specific molecules or solvents, it opens up new potential uses that have previously not been explored.

 Explore further: Graphene sieve turns seawater into drinking water

More information: Q. Yang et al. Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation, Nature Materials (2017). DOI: 10.1038/nmat5025

 

Strong current of energy runs through MIT: Robust community focused on fueling the world’s future +Video


MIT-Energy-Past-Future-borders-01 small_0Top row (l-r): Tata Center spinoff Khethworks develops affordable irrigation for the developing world; students discuss utility research in Washington; thin, lightweight solar cell developed by Professor Vladimir Bulović and team. Bottom row (l-r): MIT’s record-setting Alcator tokamak fusion research reactor; a researcher in the MIT Energy Laboratory’s Combustion Research Facility; Professor Kripa Varanasi, whose research on slippery surfaces has led to a spinoff co-founded with Associate Provost Karen Gleason.

Photos: Tata Center for Technology and Design, MITEI, Joel Jean and Anna Osherov, Bob Mumgaard/PSFC, Energy Laboratory Archives, Bryce Vickmark

Research, education, and student activities help create a robust community focused on fueling the world’s future.

On any given day at MIT, undergraduates design hydro-powered desalination systems, graduate students test alternative fuels, and professors work to tap the huge energy-generating potential of nuclear fusion, biomaterials, and more. While some MIT researchers are modeling the impacts of policy on energy markets, others are experimenting with electrochemical forms of energy storage.

This is the robust energy community at MIT. Developed over the past 10 years with the guidance and support of the MIT Energy Initiative (MITEI) — and with roots extending back into the early days of the Institute — it has engaged more than 300 faculty members and spans more than 900 research projects across all five schools.

In addition, MIT offers a multidisciplinary energy minor and myriad energy-related events and activities throughout the year. Together, these efforts ensure that students who arrive on campus with an interest in energy have free rein to pursue their ambitions.

Opportunities for students

“The MIT energy ecosystem is an incredible system, and it’s built from the ground up,” says Robert C. Armstrong, a professor of chemical engineering and the director of MITEI, which is overseen at the Institute level by Vice President for Research Maria Zuber. “It begins with extensive student involvement in energy.” MITnano_ 042216 InfCorrTerraceView_label (1)

Opportunities begin the moment undergraduates arrive on campus, with a freshman pre-orientation program offered through MITEI that includes such hands-on activities as building motors and visiting the Institute’s nuclear research reactor.

“I got accepted into the pre-orientation program and from there, I was just hooked. I learned about solar technology, wind technology, different types of alternative fuels, bio fuels, even wave power,” says graduate student Priyanka Chatterjee ’15, who minored in energy studies and majored in mechanical and ocean engineering.

Those who choose the minor take a core set of subjects encompassing energy science, technology, and social science. Those interested in a deep dive into research can participate in the Energy Undergraduate Research Opportunities Program (UROP), which provides full-time summer positions. UROP students are mentored by graduate students and postdocs, many of them members of the Society of Energy Fellows, who are also conducting their own energy research at MIT.

For extracurricular activities, students can join the MIT Energy Club, which is among the largest student-run organizations at MIT with more than 5,000 members. They can also compete for the MIT Clean Energy Prize, a student competition that awards more than $200,000 each year for energy innovation. And there are many other opportunities.

The Tata Center for Technology and Design, now in its sixth year, extends MIT’s reach abroad. It supports 65 graduate students every year who conduct research central to improving life in developing countries — including lowering costs of rural electrification and using solar energy in novel ways.

Students have other opportunities to conduct and share energy research internationally as well.

“Over the years, MITEI has made it possible for several of the students I’ve advised to engage more directly in global energy and climate policy negotiations,” says Valerie Karplus, an assistant professor of global economics and management. “In 2015, I joined them at the Paris climate conference, which was a tremendous educational and outreach experience for all of us.”

Holistic problem-solving

“What is important is to provide our students a holistic understanding of the energy challenges,” says MIT Associate Dean for Innovation Vladimir Bulović.

Adds Karplus: “There’s been an evolution in thinking from ‘How do we build a better mousetrap?’ to ‘How do we bring about change in society at a system level?’”

This kind of thinking is at the root of MIT’s multidisciplinary approach to addressing the global energy challenge — and it has been since MITEI was conceived and launched by then-MIT President Susan Hockfield, a professor of neuroscience. While energy research has been part of the Institute since its founding (MIT’s first president, William Barton Rogers, famously collapsed and died after uttering the words “bituminous coal” at the 1882 commencement), the concerted effort to connect researchers across the five schools for collaborative projects is a more recent development.

“The objective of MITEI was really to solve the big energy problems, which we feel needs all of the schools’ and departments’ contributions,” says Ernest J. Moniz, a professor emeritus of physics and special advisor to MIT’s president. Moniz was the founding director of MITEI before serving as U.S. Secretary of Energy during President Obama’s administration.

Hockfield says great technology by itself “can’t go anywhere without great policy.”

“It’s the economics, it’s the sociology, it’s the science and the engineering, it’s the architecture — it’s all of the pieces of MIT that had to come together if we were going to develop really impactful sustainable energy solutions,” she says.

This multidisciplinary approach is evident in much of MIT’s energy research — notably the series of comprehensive studies MITEI has conducted on such topics as the future of solar energy, natural gas, the electric grid, and more.

“To make a better world, it’s essential that we figure out how to take what we’ve learned at MIT in energy and get that out into the world,” Armstrong says.

Fostering collaborations

MITEI’s eight low-carbon energy research centers — focused on a range of topics from materials design to solar generation to carbon capture and storage — similarly address challenges on multiple technology and policy fronts. These centers are a core component of MIT’s five-year Plan for Action on Climate Change, announced by President L. Rafael Reif in October 2015. The centers employ a strategy that has been fundamental to MIT’s energy work since the founding of MITEI: broad, sustained collaboration with stakeholders from industry, government, and the philanthropic and non-governmental organization communities.

“It’s one thing to do research that’s interesting in a laboratory. It’s something very different to take that laboratory discovery into the world and deliver practical applications,” Hockfield says. “Our collaboration with industry allowed us to do that with a kind of alacrity that we could never have done on our own.”

For example, MITEI’s members have supported more than 160 energy-focused research projects, representing $21.4 million in funding over the past nine years, through the Seed Fund Program. Projects have led to follow-on federal and industry funding, startup companies, and pilot plants for solar desalinization systems in India and Gaza, among other outcomes.

What has MIT’s energy community as a whole accomplished over the past decade? Hockfield says it’s raised the visibility of the world’s energy problems, contributed solutions — both technical and sociopolitical — and provided “an army of young people” to lead the way to a sustainable energy future.

“I couldn’t be prouder of what MIT has contributed,” she says. “We are in the midst of a reinvention of how we make energy and how we use energy. And we will develop sustainable energy practices for a larger population, a wealthier population, and a healthier planet.”

 

MIT: Material (molybdenum ditelluride) could bring optical communication onto silicon chips


MIT-Silicon-Light-1_0

Researchers have designed a light-emitter and detector that can be integrated into silicon CMOS chips. This illustration shows a molybdenum ditelluride light source for silicon photonics. Image: Sampson Wilcox

Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers.

The huge increase in computing performance in recent decades has been achieved by squeezing ever more transistors into a tighter space on microchips.

However, this downsizing has also meant packing the wiring within microprocessors ever more tightly together, leading to effects such as signal leakage between components, which can slow down communication between different parts of the chip. This delay, known as the “interconnect bottleneck,” is becoming an increasing problem in high-speed computing systems.

One way to tackle the interconnect bottleneck is to use light rather than wires to communicate between different parts of a microchip. This is no easy task, however, as silicon, the material used to build chips, does not emit light easily, according to Pablo Jarillo-Herrero, an associate professor of physics at MIT.

Now, in a paper published today in the journal Nature Nanotechnology, researchers describe a light emitter and detector that can be integrated into silicon CMOS chips. The paper’s first author is MIT postdoc Ya-Qing Bie, who is joined by Jarillo-Herrero and an interdisciplinary team including Dirk Englund, an associate professor of electrical engineering and computer science at MIT.

The device is built from a semiconductor material called molybdenum ditelluride. This ultrathin semiconductor belongs to an emerging group of materials known as two-dimensional transition-metal dichalcogenides.

Unlike conventional semiconductors, the material can be stacked on top of silicon wafers, Jarillo-Herrero says.

“Researchers have been trying to find materials that are compatible with silicon, in order to bring optoelectronics and optical communication on-chip, but so far this has proven very difficult,” Jarillo-Herrero says. “For example, gallium arsenide is very good for optics, but it cannot be grown on silicon very easily because the two semiconductors are incompatible.”

In contrast, the 2-D molybdenum ditelluride can be mechanically attached to any material, Jarillo-Herrero says.

Another difficulty with integrating other semiconductors with silicon is that the materials typically emit light in the visible range, but light at these wavelengths is simply absorbed by silicon.

Molybdenum ditelluride emits light in the infrared range, which is not absorbed by silicon, meaning it can be used for on-chip communication.

To use the material as a light emitter, the researchers first had to convert it into a P-N junction diode, a device in which one side, the P side, is positively charged, while the other, N side, is negatively charged.

In conventional semiconductors, this is typically done by introducing chemical impurities into the material. With the new class of 2-D materials, however, it can be done by simply applying a voltage across metallic gate electrodes placed side-by-side on top of the material.

“That is a significant breakthrough, because it means we do not need to introduce chemical impurities into the material [to create the diode]. We can do it electrically,” Jarillo-Herrero says.

Once the diode is produced, the researchers run a current through the device, causing it to emit light.

“So by using diodes made of molybdenum ditelluride, we are able to fabricate light-emitting diodes (LEDs) compatible with silicon chips,” Jarillo-Herrero says.

The device can also be switched to operate as a photodetector, by reversing the polarity of the voltage applied to the device. This causes it to stop conducting electricity until a light shines on it, when the current restarts.

In this way, the devices are able to both transmit and receive optical signals.

The device is a proof of concept, and a great deal of work still needs to be done before the technology can be developed into a commercial product, Jarillo-Herrero says.

This paper fills an important gap in integrated photonics, by realizing a high-performance silicon-CMOS-compatible light source, says Frank Koppens, a professor of quantum nano-optoelectronics at the Institute of Photonic Sciences in Barcelona, Spain, who was not involved in the research.

“This work shows that 2-D materials and Si-CMOS and silicon photonics are a natural match, and we will surely see many more applications coming out of this [area] in the years to come,” Koppens says.

The researchers are now investigating other materials that could be used for on-chip optical communication.

Most telecommunication systems, for example, operate using light with a wavelength of 1.3 or 1.5 micrometers, Jarillo-Herrero says.

However, molybdenum ditelluride emits light at 1.1 micrometers. This makes it suitable for use in the silicon chips found in computers, but unsuitable for telecommunications systems.

“It would be highly desirable if we could develop a similar material, which could emit and detect light at 1.3 or 1.5 micrometers in wavelength, where telecommunication through optical fiber operates,” he says.

To this end, the researchers are exploring another ultrathin material called black phosphorus, which can be tuned to emit light at different wavelengths by altering the number of layers used. They hope to develop devices with the necessary number of layers to allow them to emit light at the two wavelengths while remaining compatible with silicon.

“The hope is that if we are able to communicate on-chip via optical signals instead of electronic signals, we will be able to do so more quickly, and while consuming less power,” Jarillo-Herrero says.

The research was supported by Center for Excitonics, an EFRC funded by the U.S. Department of Energy.

Rice U: Nano-Shells could deliver more chemo with fewer side effects


Rice Nano shells 171108143658_1_540x360
Researchers from Rice University and Northwestern University loaded light-activated nano-shells (gold and light blue) with the anticancer drug lapatinib (yellow) by encasing the drug in an envelope of albumin (blue). Light from a near-infrared laser (center) was used to remotely trigger the release of the drug (right) after the nano-shells were taken up by cancer cells. Credit: A. Goodman/Rice University

Researchers investigating ways to deliver high doses of cancer-killing drugs inside tumors have shown they can use a laser and light-activated gold nanoparticles to remotely trigger the release of approved cancer drugs inside cancer cells in laboratory cultures.

The study by researchers at Rice University and Northwestern University Feinberg School of Medicine appears in this week’s online Early Edition of the Proceedings of the National Academy of Sciences. It employed gold nanoshells to deliver toxic doses of two drugs — lapatinib and docetaxel — inside breast cancer cells. The researchers showed they could use a laser to remotely trigger the particles to release the drugs after they entered the cells.

Though the tests were conducted with cell cultures in a lab, the research was designed to demonstrate clinical applicability: The nanoparticles are nontoxic, the drugs are widely used and the low-power, infrared laser can noninvasively shine through tissue and reach tumors several inches below the skin.

“In future studies, we plan to use a Trojan-horse strategy to get the drug-laden nanoshells inside tumors,” said Naomi Halas, an engineer, chemist and physicist at Rice University who invented gold nanoshells and has spent more than 15 years researching their anticancer potential. “Macrophages, a type of white blood cell that’s been shown to penetrate tumors, will carry the drug-particle complexes into tumors, and once there we use a laser to release the drugs.”

Co-author Susan Clare, a research associate professor of surgery at the Northwestern University Feinberg School of Medicine, said the PNAS study was designed to demonstrate the feasibility of the Trojan-horse approach. In addition to demonstrating that drugs could be released inside cancer cells, the study also showed that in macrophages, the drugs did not detach prior to triggering.

“Getting chemotherapeutic drugs to penetrate tumors is very challenging,” said Clare, also a Northwestern Medicine breast cancer surgeon. “Drugs tend to get pushed out of tumors rather than drawn in. To get an effective dose at the tumor, patients often have to take so much of the drug that nausea and other side effects become severe. Our hope is that the combination of macrophages and triggered drug-release will boost the effective dose of drugs within tumors so that patients can take less rather than more.”

If the approach works, Clare said, it could result in fewer side effects and potentially be used to treat many kinds of cancer. For example, one of the drugs in the study, lapatinib, is part of a broad class of chemotherapies called tyrosine kinase inhibitors that target specific proteins linked to different types of cancer. Other Federal Drug Administration-approved drugs in the class include imatinib (leukemia), gefitinib (breast, lung), erlotinib (lung, pancreatic), sunitinib (stomach, kidney) and sorafenib (liver, thyroid and kidney).

“All the tyrosine kinase inhibitors are notoriously insoluble in water,” said Amanda Goodman, a Rice alumna and lead author of the PNAS study. “As a drug class, they have poor bioavailability, which means that a relatively small proportion of the drug in each pill is actually killing cancer cells. If our method works for lapatinib and breast cancer, it may also work for the other drugs in the class.”

Halas invented nanoshells at Rice in the 1990s. About 20 times smaller than a red blood cell, they are made of a sphere of glass covered by a thin layer of gold. Nanoshells can be tuned to capture energy from specific wavelengths of light, including near-infrared (near-IR), a nonvisible wavelength that passes through most tissues in the body. Nanospectra Biosciences, a licensee of this technology, has performed several clinical trials over the past decade using nanoshells as photothermal agents that destroy tumors with infrared light.

Clare and Halas’ collaboration on nanoshell-based drug delivery began more than 10 years ago. In earlier work, they showed that a near-IR continuous-wave laser — the same kind that produces heat in the photothermal applications of nanoshells — could be used to trigger the release of drugs from nanoshells.

In the latest study, Goodman contrasted the use of continuous-wave laser triggering and triggering with a low-power pulse laser. Using each type of laser, she demonstrated the remotely triggered release of drugs from two types of nanoshell-drug conjugates. One type used a DNA linker and the drug docetaxel, and the other employed a coating of the blood protein albumin to trap and hold lapatinib. In each case, Goodman found she could trigger the release of the drug after the nanoshells were taken up inside cancer cells. She also found no measureable premature release of drugs in macrophages in either case.

Halas and Clare said they hope to begin animal tests of the technology soon and have an established mouse model that could be used for the testing.

“I’m particularly excited about the potential for lapatinib,” Clare said. “The first time I heard about Naomi’s work, I wondered if it might be the answer to delivering drugs into the anoxic (depleted of oxygen) interior of tumors where some of the most aggressive cancer cells lurk. As clinicians, we’re always looking for ways to keep cancer from coming back months or years later, and I am hopeful this can do that.”

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MIT and Lamborghini to develop graphene-enhanced supercar – Powered Only by Supercapacitors



 November 10, 2017

Lamborghini and MIT have announced a collaboration on a 3-year project to develop a graphene-enhanced supercapacitor electric vehicle. 

The Lamborghini-MIT partnership could, however, end up being extended as there is no target date for the car’s completion.


MIT and Lamborghini develop graphene-enhanced supercar image

The planned graphene-enhanced Terzo Millennio (“third millennium”) supercar may be a real gamechanger. 

This concept car is to be a fully electric, supercapacitor-powered automobile that can be charged in minutes – with no bulky battery. 

It will reportedly be “covered in a sheet of graphene”, but this description does not sound extremely accurate… We will have to wait for further information on this project.

According to reports, the bodywork of the car will utilize Lamborghini’s expertise in carbon fibre, which results in significant weight reduction. 

However, the joint plan is apparently for the carbon panels to also act as an accumulator for energy storage. 

But Lamborghini and MIT also want the car to self-heal. Cracks and minor damage will be automatically detected in the carbon structure and then repaired using “microchannels” in the bodywork filled with “healing chemistries”…. stay tuned … !

Source:  wired