Tag Archives: United Arab Emirates

Memristors at Masdar

The Masdar Institute of Science and Technology (Abu Dhabi, United Arab Emirates; Masdar Institute Wikipedia entry) featured its work with memristors in an Oct. 1, 2017 Masdar Institute press release by Erica Solomon (for anyone who’s interested, I have a simple description of memristors and links to more posts about them after the press release),

Researchers Develop New Memristor Prototype Capable of Performing Complex Operations at High-Speed and Low Power, Could Lead to Advancements in Internet of Things, Portable Healthcare Sensing and other Embedded Technologies

Computer circuits in development at the Khalifa University of Science and Technology could make future computers much more compact, efficient and powerful thanks to advancements being made in memory technologies that combine processing and memory storage functions into one densely packed “memristor.”

Enabling faster, smaller and ultra-low-power computers with memristors could have a big impact on embedded technologies, which enable Internet of Things (IoT), artificial intelligence, and portable healthcare sensing systems, says Dr. Baker Mohammad, Associate Professor of Electrical and Computer Engineering. Dr. Mohammad co-authored a book on memristor technologies, which has just been released by Springer, a leading global scientific publisher of books and journals, with Class of 2017 PhD graduate Heba Abunahla. The book, titled Memristor Technology: Synthesis and Modeling for Sensing and Security Applications, provides readers with a single-source guide to fabricate, characterize and model memristor devices for sensing applications.

The pair also contributed to a paper on memristor research that was published in IEEE Transactions on Circuits and Systems I: Regular Papers earlier this month with Class of 2017 MSc graduate Muath Abu Lebdeh and Dr. Mahmoud Al-Qutayri, Professor of Electrical and Computer Engineering.PhD student Yasmin Halawani is also an active member of Dr. Mohammad’s research team.

Conventional computers rely on energy and time-consuming processes to move information back and forth between the computer central processing unit (CPU) and the memory, which are separately located. A memristor, which is an electrical resistor that remembers how much current flows through it, can bridge the gap between computation and storage. Instead of fetching data from the memory and sending that data to the CPU where it is then processed, memristors have the potential to store and process data simultaneously.

“Memristors allow computers to perform many operations at the same time without having to move data around, thereby reducing latency, energy requirements, costs and chip size,” Dr. Mohammad explained. “We are focused on extending the logic gate design of the current memristor architecture with one that leads to even greater reduction of latency, energy dissipation and size.”

Logic gates control an electronics logical operation on one or more binary inputs and typically produce a single binary output. That is why they are at the heart of what makes a computer work, allowing a CPU to carry out a given set of instructions, which are received as electrical signals, using one or a combination of the seven basic logical operations: AND, OR, NOT, XOR, XNOR, NAND and NOR.

The team’s latest work is aimed at advancing a memristor’s ability to perform a complex logic operation, known as the XNOR (Exclusive NOR) logic gate function, which is the most complex logic gate operation among the seven basic logic gates types.

Designing memristive logic gates is difficult, as they require that each electrical input and output be in the form of electrical resistance rather than electrical voltage.

“However, we were able to successfully design an XNOR logic gate prototype with a novel structure, by layering bipolar and unipolar memristor types in a novel heterogeneous structure, which led to a reduction in latency and energy consumption for a memristive XNOR logic circuit gate by 50% compared to state-of the art state full logic proposed by leading research institutes,” Dr. Mohammad revealed.

The team’s current work builds on five years of research in the field of memristors, which is expected to reach a market value of US$384 million by 2025, according to a recent report from Research and Markets. Up to now, the team has fabricated and characterized several memristor prototypes, assessing how different design structures influence efficiency and inform potential applications. Some innovative memristor technology applications the team discovered include machine vision, radiation sensing and diabetes detection. Two patents have already been issued by the US Patents and Trademark Office (USPTO) for novel memristor designs invented by the team, with two additional patents pending.

Their robust research efforts have also led to the publication of several papers on the technology in high impact journals, including The Journal of Physical Chemistry, Materials Chemistry and Physics, and IEEE TCAS. This strong technology base paved the way for undergraduate senior students Reem Aldahmani, Amani Alshkeili, and Reem Jassem Jaffar to build novel and efficient memristive sensing prototypes.

The memristor research is also set to get an additional boost thanks to the new University merger, which Dr. Mohammad believes could help expedite the team’s research and development efforts through convenient and continuous access to the wider range of specialized facilities and tools the new university has on offer.

The team’s prototype memristors are now in the laboratory prototype stage, and Dr. Mohammad plans to initiate discussions for internal partnership opportunities with the Khalifa University Robotics Institute, followed by external collaboration with leading semiconductor companies such as Abu Dhabi-owned GlobalFoundries, to accelerate the transfer of his team’s technology to the market.

With initial positive findings and the promise of further development through the University’s enhanced portfolio of research facilities, this project is a perfect demonstration of how the Khalifa University of Science and Technology is pushing the envelope of electronics and semiconductor technologies to help transform Abu Dhabi into a high-tech hub for research and entrepreneurship.

h/t Oct. 4, 2017 Nanowerk news item

Slightly restating it from the press release, a memristor is a nanoscale electrical component which mimics neural plasticity. Memristor combines the word ‘memory’ with ‘resistor’.

For those who’d like a little more, there are three components: capacitors, inductors, and resistors which make up an electrical circuit. The resistor is the circuit element which represents the resistance to the flow of electric current.  As for how this relates to the memristor (from the Memristor Wikipedia entry; Note: Links have been removed),

The memristor’s electrical resistance is not constant but depends on the history of current that had previously flowed through the device, i.e., its present resistance depends on how much electric charge has flowed in what direction through it in the past; the device remembers its history — the so-called non-volatility property.[2] When the electric power supply is turned off, the memristor remembers its most recent resistance until it is turned on again

The memristor could lead to more energy-saving devices but much of the current (pun noted) interest lies in its similarity to neural plasticity and its potential application on neuromorphic engineering (brainlike computing).

Here’s a sampling of some of the more recent memristor postings on this blog:

August 24, 2017: Neuristors and brainlike computing

June 28, 2017: Dr. Wei Lu and bio-inspired ‘memristor’ chips

May 2, 2017: Predicting how a memristor functions

December 30, 2016: Changing synaptic connectivity with a memristor

December 5, 2016: The memristor as computing device

November 1, 2016: The memristor as the ‘missing link’ in bioelectronic medicine?

You can find more by using ‘memristor’ as the search term in the blog search function or on the search engine of your choice.

Carbon nanotubes for water desalination

In discussions about water desalination and carbon nanomaterials,  it’s graphene that’s usually mentioned these days. By contrast, scientists from the US Department of Energy’s Lawrence Livermore National Laboratory (LLNL) have turned to carbon nanotubes,

There are two news items about the work at LLNL on ScienceDaily, this first one originated by the American Association for the Advancement of Science (AAAS) offers a succinct summary of the work (from an August 24, 2017 news item on ScienceDaily,

At just the right size, carbon nanotubes can filter water with better efficiency than biological proteins, a new study reveals. The results could pave the way to new water filtration systems, at a time when demands for fresh water pose a global threat to sustainable development.

A class of biological proteins, called aquaporins, is able to effectively filter water, yet scientists have not been able to manufacture scalable systems that mimic this ability. Aquaporins usually exhibit channels for filtering water molecules at a narrow width of 0.3 nanometers, which forces the water molecules into a single-file chain.

Here, Ramya H. Tunuguntla and colleagues experimented with nanotubes of different widths to see which ones are best for filtering water. Intriguingly, they found that carbon nanotubes with a width of 0.8 nanometers outperformed aquaporins in filtering efficiency by a factor of six.

These narrow carbon nanotube porins (nCNTPs) were still slim enough to force the water molecules into a single-file chain. The researchers attribute the differences between aquaporins and nCNTPS to differences in hydrogen bonding — whereas pore-lining residues in aquaporins can donate or accept H bonds to incoming water molecules, the walls of CNTPs cannot form H bonds, permitting unimpeded water flow.

The nCNTPs in this study maintained permeability exceeding that of typical saltwater, only diminishing at very high salt concentrations. Lastly, the team found that by changing the charges at the mouth of the nanotube, they can alter the ion selectivity. This advancement is highlighted in a Perspective [in Science magazine] by Zuzanna Siwy and Francesco Fornasiero.

The second Aug. 24, 2017 news item on ScienceDaily offers a more technical  perspective,

Lawrence Livermore scientists, in collaboration with researchers at Northeastern University, have developed carbon nanotube pores that can exclude salt from seawater. The team also found that water permeability in carbon nanotubes (CNTs) with diameters smaller than a nanometer (0.8 nm) exceeds that of wider carbon nanotubes by an order of magnitude.

The nanotubes, hollow structures made of carbon atoms in a unique arrangement, are more than 50,000 times thinner than a human hair. The super smooth inner surface of the nanotube is responsible for their remarkably high water permeability, while the tiny pore size blocks larger salt ions.

There’s a rather lovely illustration for this work,

An artist’s depiction of the promise of carbon nanotube porins for desalination. The image depicts a stylized carbon nanotube pipe that delivers clean desalinated water from the ocean to a kitchen tap. Image by Ryan Chen/LLNL

An Aug. 24, 2017 LLNL news release (also on EurekAlert), which originated the second news item, proceeds

Increasing demands for fresh water pose a global threat to sustainable development, resulting in water scarcity for 4 billion people. Current water purification technologies can benefit from the development of membranes with specialized pores that mimic highly efficient and water selective biological proteins.

“We found that carbon nanotubes with diameters smaller than a nanometer bear a key structural feature that enables enhanced transport. The narrow hydrophobic channel forces water to translocate in a single-file arrangement, a phenomenon similar to that found in the most efficient biological water transporters,” said Ramya Tunuguntla, an LLNL postdoctoral researcher and co-author of the manuscript appearing in the Aug. 24 [2017]edition of Science.

Computer simulations and experimental studies of water transport through CNTs with diameters larger than 1 nm showed enhanced water flow, but did not match the transport efficiency of biological proteins and did not separate salt efficiently, especially at higher salinities. The key breakthrough achieved by the LLNL team was to use smaller-diameter nanotubes that delivered the required boost in performance.

“These studies revealed the details of the water transport mechanism and showed that rational manipulation of these parameters can enhance pore efficiency,” said Meni Wanunu, a physics professor at Northeastern University and co-author on the study.

“Carbon nanotubes are a unique platform for studying molecular transport and nanofluidics,” said Alex Noy, LLNL principal investigator on the CNT project and a senior author on the paper. “Their sub-nanometer size, atomically smooth surfaces and similarity to cellular water transport channels make them exceptionally suited for this purpose, and it is very exciting to make a synthetic water channel that performs better than nature’s own.”

This discovery by the LLNL scientists and their colleagues has clear implications for the next generation of water purification technologies and will spur a renewed interest in development of the next generation of high-flux membranes.

Here’s a link to and a citation for the paper,

Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins by Ramya H. Tunuguntla, Robert Y. Henley, Yun-Chiao Yao, Tuan Anh Pham, Meni Wanunu, Aleksandr Noy. Science 25 Aug 2017: Vol. 357, Issue 6353, pp. 792-796 DOI: 10.1126/science.aan2438

This paper is behind a paywall.

And, Northeastern University issued an August 25, 2017 news release (also on EurekAlert) by Allie Nicodemo,

Earth is 70 percent water, but only a tiny portion—0.007 percent—is available to drink.

As potable water sources dwindle, global population increases every year. One potential solution to quenching the planet’s thirst is through desalinization—the process of removing salt from seawater. While tantalizing, this approach has always been too expensive and energy intensive for large-scale feasibility.

Now, researchers from Northeastern have made a discovery that could change that, making desalinization easier, faster and cheaper than ever before. In a paper published Thursday [August 24, 2017] in Science, the group describes how carbon nanotubes of a certain size act as the perfect filter for salt—the smallest and most abundant water contaminant.

Filtering water is tricky because water molecules want to stick together. The “H” in H2O is hydrogen, and hydrogen bonds are strong, requiring a lot of energy to separate. Water tends to bulk up and resist being filtered. But nanotubes do it rapidly, with ease.

A carbon nanotube is like an impossibly small rolled up sheet of paper, about a nanometer in diameter. For comparison, the diameter of a human hair is 50 to 70 micrometers—50,000 times wider. The tube’s miniscule size, exactly 0.8 nm, only allows one water molecule to pass through at a time. This single-file lineup disrupts the hydrogen bonds, so water can be pushed through the tubes at an accelerated pace, with no bulking.

“You can imagine if you’re a group of people trying to run through the hallway holding hands, it’s going to be a lot slower than running through the hallway single-file,” said co-author Meni Wanunu, associate professor of physics at Northeastern. Wanunu and post doctoral student Robert Henley collaborated with scientists at the Lawrence Livermore National Laboratory in California to conduct the research.

Scientists led by Aleksandr Noy at Lawrence Livermore discovered last year [2016] that carbon nanotubes were an ideal channel for proton transport. For this new study, Henley brought expertise and technology from Wanunu’s Nanoscale Biophysics Lab to Noy’s lab, and together they took the research one step further.

In addition to being precisely the right size for passing single water molecules, carbon nanotubes have a negative electric charge. This causes them to reject anything with the same charge, like the negative ions in salt, as well as other unwanted particles.

“While salt has a hard time passing through because of the charge, water is a neutral molecule and passes through easily,” Wanunu said. Scientists in Noy’s lab had theorized that carbon nanotubes could be designed for specific ion selectivity, but they didn’t have a reliable system of measurement. Luckily, “That’s the bread and butter of what we do in Meni’s lab,” Henley said. “It created a nice symbiotic relationship.”

“Robert brought the cutting-edge measurement and design capabilities of Wanunu’s group to my lab, and he was indispensable in developing a new platform that we used to measure the ion selectivity of the nanotubes,” Noy said.

The result is a novel system that could have major implications for the future of water security. The study showed that carbon nanotubes are better at desalinization than any other existing method— natural or man-made.

To keep their momentum going, the two labs have partnered with a leading water purification organization based in Israel. And the group was recently awarded a National Science Foundation/Binational Science Foundation grant to conduct further studies and develop water filtration platforms based on their new method. As they continue the research, the researchers hope to start programs where students can learn the latest on water filtration technology—with the goal of increasing that 0.007 percent.

As is usual in these cases there’s a fair degree of repetition but there’s always at least one nugget of new information, in this case, a link to Israel. As I noted many times, the Middle East is experiencing serious water issues. My most recent ‘water and the Middle East’ piece is an August 21, 2017 post about rainmaking at the Masdar Institute in United Arab Emirates. Approximately 50% of the way down the posting, I mention Israel and Palestine’s conflict over water.

International Women’s Day March 8, 2017 and UNESCO/L’Oréal’s For Women in Science (Rising Talents)

Before getting to the science, here’s a little music in honour of March 8, 2017 International Women’s Day,

There is is a Wikipedia entry devoted to Rise Up (Parachute Club song), Note: Links have been removed<

“Rise Up” is a pop song recorded by the Canadian group Parachute Club on their self-titled 1983 album. It was produced and engineered by Daniel Lanois, and written by Parachute Club members Billy Bryans, Lauri Conger, Lorraine Segato and Steve Webster with lyrics contributed by filmmaker Lynne Fernie.

An upbeat call for peace, celebration, and “freedom / to love who we please,” the song was a national hit in Canada, and was hailed as a unique achievement in Canadian pop music:

“ Rarely does one experience a piece of music in white North America where the barrier between participant and observer breaks down. Rise Up rises right up and breaks down the wall.[1] ”

According to Segato, the song was not written with any one individual group in mind, but as a universal anthem of freedom and equality;[2] Fernie described the song’s lyrics as having been inspired in part by West Coast First Nations rituals in which young girls would “rise up” at dawn to adopt their adult names as a rite of passage.[3]

It remains the band’s most famous song, and has been adopted as an activist anthem for causes as diverse as gay rights, feminism, anti-racism and the New Democratic Party.[4] As well, the song’s reggae and soca-influenced rhythms made it the first significant commercial breakthrough for Caribbean music in Canada.

L’Oréal UNESCO For Women in Science

From a March 8, 2017 UNESCO press release (received via email),

Fifteen outstanding young women researchers, selected
among more than 250 candidates in the framework of the 19th edition of
the L’Oréal-UNESCO For Women in Science awards, will receive the
International Rising Talent fellowship during a gala on 21 March at the
hotel Pullman Tour Eiffel de Paris. By recognizing their achievements at
a key moment in their careers, the _For Women in Science programme aims
to help them pursue their research.

Since 1998, the L’Oréal-UNESCO _For Women in Science programme [1]
has highlighted the achievements of outstanding women scientists and
supported promising younger women who are in the early stages of their
scientific careers. Selected among the best national and regional
L’Oréal-UNESCO fellows, the International Rising Talents come from
all regions of the world (Africa and Arab States, Asia-Pacific, Europe,
Latin America and North America).

Together with the five laureates of the 2017 L’Oreal-UNESCO For Women
in Science awards [2], they will participate in a week of events,
training and exchanges that will culminate with the award ceremony on 23
March 2017 at the Mutualité in Paris.

The 2017 International Rising Talent are recognized for their work in
the following five categories:


Fundamental medicine
In a coma: is the patient conscious or unconscious?     * ASSOCIATE

Clinical medicine
Recognizing Alzheimer’s before the first signs appear.


Biological Sciences
Neurodegenerative diseases: untangling aggregated proteins.
* DOCTOR NAM-KYUNG YU, Republic of Korea
Biological Sciences
Rett syndrome: neuronal cells come under fire
Biological Sciences
Better understanding the immune system.
Biological Sciences
Better tissue healing.

Finding potential new sources of drugs

Biological Sciences
New antibiotics are right under our feet.
Biological Sciences
Unraveling the secrets of entangled proteins.


* MS NAZEK EL-ATAB, United Arab Emirates
Electrical, Electronic and Computer Engineering
Miniaturizing electronics without losing memory.
Piercing the secrets of cosmic radiation.
Material Sciences
Trapping radioactivity.
Unlocking the potential of energy resources with nanochemistry.


Biological Sciences
Predicting how animal biodiversity will evolve.
* DOCTOR SAM GILES, United Kingdom
Biological Sciences
Taking another look at the evolution of vertebrates thanks to their
Astronomy and Space Sciences
Looking at the birth of distant suns and planets to better understand
the solar system.

Congratulations to all of the winners!

You can find out more about these awards and others on the 2017 L’Oréal-UNESCO For Women in Science Awards webpage or on the For Women In Science website. (Again in honour of the 2017 International Women’s Day, I was the 92758th signer of the For Women in Science Manifesto.)

International Women’s Day origins

Thank you to Wikipedia (Note: Links have been removed),

International Women’s Day (IWD), originally called International Working Women’s Day, is celebrated on March 8 every year.[2] It commemorates the movement for women’s rights.

The earliest Women’s Day observance was held on February 28, 1909, in New York and organized by the Socialist Party of America.[3] On March 8, 1917, in the capital of the Russian Empire, Petrograd, a demonstration of women textile workers began, covering the whole city. This was the beginning of the Russian Revolution.[4] Seven days later, the Emperor of Russia Nicholas II abdicated and the provisional Government granted women the right to vote.[3] March 8 was declared a national holiday in Soviet Russia in 1917. The day was predominantly celebrated by the socialist movement and communist countries until it was adopted in 1975 by the United Nations.

It seems only fitting to bookend this post with another song (Happy International Women’s Day March 8, 2017),

While the lyrics are unabashedly romantic, the video is surprisingly moody with a bit of a ‘stalker vive’ although it does end up with her holding centre stage while singing and bouncing around in time to Walking on Sunshine.

A better buckypaper

‘Buckyballs’ is a slang term for buckminster fullerenes, spheres made up of a carbon atoms arranged in hexagons. It’s a tribute of sorts to Buckminster Fuller, an architect, designer, systems theorist and more, who developed a structure known as a geodesic dome which bears a remarkable resemblance to the carbon atom spheres known as buckyballs or buckminster fullerenes or fullerenes or C60 (for a carbon-based fullerene) for short. Carbon nanotubes are sometimes called buckytubes and there is a material known as buckypaper. A Sept. 20, 2016 news item on Nanowerk describes the latest work on buckypaper,

Researchers at the Masdar Institute of Science and Technology have developed a novel type of “buckypaper” – a thin film composed of carbon nanotubes – that has better thermal and electrical properties than most types of buckypaper previously developed. Researchers believe the innovative buckypaper could be used to create ultra-lightweight composite materials for numerous aerospace and energy applications, including advanced lightning strike protection on airplanes and more powerful lithium-ion batteries.

Masdar Institute’s Associate Professors of Mechanical and Materials Engineering Dr. Rashid Abu Al-Rub and Dr. Amal Al Ghaferi, along with Post-Doctoral Researcher Dr. Hammad Younes, developed the buckypaper with carbon nanostructures provided by global security, aerospace, and information technology company Lockheed Martin.

A Sept. 20, 2016 Masdar Institute (United Arab Emirates) press release, which originated the news item, describes the research in more detail,

The black, powdery flakes provided by Lockheed Martin’s Applied NanoStructured Solutions (ANS) contain hundreds of carbon nanotubes, which are one-atom thick sheets of graphene rolled into a tube that have extraordinary mechanical, electrical and thermal properties. Lockheed Martin’s carbon nanostructures are unique because the carbon nanotubes within each flake are all properly aligned, making them good conductors of heat and electricity.

“Lockheed Martin’s carbon nanostructures have many potential applications, but in its powdery form, it cannot be used. It has to be fabricated in a way that keeps the unique properties of the carbon nanotube,” explained Dr. Al Ghaferi. “The challenge we faced was to create something useful with the carbon nanotubes without losing any of their unique properties or disturbing the alignment.”

Dr. Younes said: “Each flake is a carbon nanostructure containing many aligned carbon nanotubes. The alignment of the tubes creates a path for conductivity, much like a wire, making the nanostructure an exceptionally good conductor of electricity.”

The Masdar Institute team mixed the carbon nanotubes with a polymer and their resulting buckypaper, which successfully maintained the alignment of the carbon nanotubes, demonstrated high thermal-electrical conductivity and superior mechanical properties.

“We have a secret recipe for self-aligning the carbon nanotubes within the buckypaper. This self-aligning is key in significantly enhancing the electrical, thermal and mechanical properties of our fabricated buckypapers,” explained Dr. Abu Al-Rub.

Despite their microscopic size – a carbon nanotube’s diameter is about 10,000 times smaller than a human hair – carbon nanotubes’ impact on technology has been huge. At the individual tube level, carbon nanotubes are 200 times stronger, five times more elastic, and five times more electrically conductive than steel.

Because of their extraordinary strength, thermal and electrical properties, and miniscule size, carbon nanotubes can be used in a number of applications, including ultra-thin energy storage devices, smaller and more efficient computer chips, photovoltaic solar cells, flexible electronics, cancer detection, and lightning-resistant coatings on airplanes.

According to a report by Global Industry Analysts Inc., the current global market for nanotubes is pegged at roughly US$5 billion and its market share is growing sharply, reflecting the rising sentiment worldwide in carbon nanotubes’ potential as a wonder technology.

Masdar Institute’s efforts to capitalize on this emerging technology have resulted in several cutting-edge carbon nanotube research projects, including an attempt to create carbon nanotube-strengthened concrete, super capacitors that can hold 50 times more charge, and a membrane that can bind organic micro-pollutants.

As the UAE moves towards a clean energy future, innovations in renewable energy storage systems and other sustainable technologies are crucial for the country’s successful transition, and researchers at Masdar Institute believe that carbon nanotubes will play a huge role in achieving energy sustainability.

Here’s a link to and a citation for the paper,

Processing and property investigation of high-density carbon nanostructured papers with superior conductive and mechanical properties by Hammad Younesa, Rashid Abu Al-Ruba, Md. Mahfuzur Rahmana, Ahmed Dalaqa, Amal Al Ghaferia, Tushar Shahb. Diamond and Related Materials Volume 68, September 2016, Pages 109–117  DOI: http://dx.doi.org/10.1016/j.diamond.2016.06.016

This paper is behind a paywall.

Self-shading electrochromic windows from the Massachusetts Institute of Technology

It’s been a while since I’ve had a story about electrochromic windows and I’ve begun to despair that they will ever reach the marketplace. Happily, the Massachusetts Institute of Technology (MIT) has supplied a ray of light (intentional wordplay). An Aug. 11, 2016 news item on Nanowerk makes the announcement,

A team of researchers at MIT has developed a new way of making windows that can switch from transparent to opaque, potentially saving energy by blocking sunlight on hot days and thus reducing air-conditioning costs. While other systems for causing glass to darken do exist, the new method offers significant advantages by combining rapid response times and low power needs.

Once the glass is switched from clear to dark, or vice versa, the new system requires little to no power to maintain its new state; unlike other materials, it only needs electricity when it’s time to switch back again.

An Aug. 11, 2016 MIT news release (also on EurekAlert), which originated the news item, explains the technology in more detail,

The new discovery uses electrochromic materials, which change their color and transparency in response to an applied voltage, Dinca [MIT professor of chemistry Mircea Dinca] explains. These are quite different from photochromic materials, such as those found in some eyeglasses that become darker when the light gets brighter. Such materials tend to have much slower response times and to undergo a smaller change in their levels of opacity.

Existing electrochromic materials suffer from similar limitations and have found only niche applications. For example, Boeing 787 aircraft have electrochromic windows that get darker to prevent bright sunlight from glaring through the cabin. The windows can be darkened by turning on the voltage, Dinca says, but “when you flip the switch, it actually takes a few minutes for the window to turn dark. Obviously, you want that to be faster.”

The reason for that slowness is that the changes within the material rely on a movement of electrons — an electric current — that gives the whole window a negative charge. Positive ions then move through the material to restore the electrical balance, creating the color-changing effect. But while electrons flow rapidly through materials, ions move much more slowly, limiting the overall reaction speed.

The MIT team overcame that by using sponge-like materials called metal-organic frameworks (MOFs), which can conduct both electrons and ions at very high speeds. Such materials have been used for about 20 years for their ability to store gases within their structure, but the MIT team was the first to harness them for their electrical and optical properties.

The other problem with existing versions of self-shading materials, Dinca says, is that “it’s hard to get a material that changes from completely transparent to, let’s say, completely black.” Even the windows in the 787 can only change to a dark shade of green, rather than becoming opaque.

In previous research on MOFs, Dinca and his students had made material that could turn from clear to shades of blue or green, but in this newly reported work they have achieved the long-sought goal of producing a coating that can go all the way from perfectly clear to nearly black (achieved by blending two complementary colors, green and red). The new material is made by combining two chemical compounds, an organic material and a metal salt. Once mixed, these self-assemble into a thin film of the switchable material.

“It’s this combination of these two, of a relatively fast switching time and a nearly black color, that has really got people excited,” Dinca says.

The new windows have the potential, he says, to do much more than just preventing glare. “These could lead to pretty significant energy savings,” he says, by drastically reducing the need for air conditioning in buildings with many windows in hot climates. “You could just flip a switch when the sun shines through the window, and turn it dark,” or even automatically make that whole side of the building go dark all at once, he says.

While the properties of the material have now been demonstrated in a laboratory setting, the team’s next step is to make a small-scale device for further testing: a 1-inch-square sample, to demonstrate the principle in action for potential investors in the technology, and to help determine what the manufacturing costs for such windows would be.

Further testing is also needed, Dinca says, to demonstrate what they have determined from preliminary testing: that once the switch is flipped and the material changes color, it requires no further power to maintain its new state. No extra power is needed until the switch is flipped to turn the material back to its former state, whether clear or opaque. Many existing electrochromic materials, by contrast, require a continuous voltage input.

In addition to smart windows, Dinca says, the material could also be used for some kinds of low-power displays, similar to displays like electronic ink (used in devices such as the Kindle and based on MIT-developed technology) but based on a completely different approach.

Not surprisingly perhaps, the research was partly funded by an organization in a region where such light-blocking windows would be particularly useful: The Masdar Institute, based in the United Arab Emirates, through a cooperative agreement with MIT. The research also received support from the U.S. Department of Energy, through the Center for Excitonics, an Energy Frontier Center.

Here’s a link to and a citation for the paper,

Transparent-to-Dark Electrochromic Behavior in Naphthalene-Diimide-Based Mesoporous MOF-74 Analogs by Khalid AlKaabi, Casey R. Wade, Mircea Dincă. Chem, Volume 1, Issue 2, 11 August 2016, Pages 264–272 doi:10.1016/j.chempr.2016.06.013

This paper is behind a paywall.

For those curious about the windows, there’s this .gif from MIT,