MIT: Lighting the Way to Better Battery Technology


MIT New Battery 0720 Supratim_Das_9Supratim Das is determined to demystify lithium-ion batteries, by first understanding their flaws.  Photo: Lillie Paquette/School of Engineering

Doctoral candidate Supratim Das wants the world to know how to make longer-lasting batteries that charge mobile phones and electric cars.

Supratim Das’s quest for the perfect battery began in the dark. Growing up in Kolkata, India, Das saw that a ready supply of electric power was a luxury his family didn’t have. “I wanted to do something about it,” Das says. Now a fourth-year PhD candidate in MIT chemical engineering who’s months away from defending his thesis, he’s been investigating what causes the batteries that power the world’s mobile phones and electric cars to deteriorate over time.

Lithium-ion batteries, so-named for the movement of lithium ions that make them work, power most rechargeable devices today. The element lithium has properties that allow lithium-ion batteries to be both portable and powerful; the 2019 Nobel Prize in Chemistry was awarded to scientists who helped develop them in the late 1970s. But despite their widespread use, lithium-ion batteries, essentially a black box during operation, harbor mysteries that prevent scientists from unlocking their full potential. Das is determined to demystify them, by first understanding their flaws.

In principle, rechargeable batteries shouldn’t expire. In practice, however, they can only be recharged a finite number of times before they lose their ability to hold a charge. An ordinary battery eventually stops working when the terminals of the battery — called electrodes — are permanently altered by the ions passing from one terminal of the battery to the other. In a rechargeable battery, the electrodes recover when an external charger sends those ions back where they came from.

Lithium ion batteries work the same way. Typically, one electrode is made of graphite, and the other of lithium compounds with transition metals such as iron, cobalt, or nickel. At the lithium electrode, lithium atoms part ways with their electrons, swim through the battery fluid (electrolyte), and wait at the other electrode. Meanwhile, the electrons take the long way around. They flow out the battery, through a device that needs the power, and into the second electrode, where they rejoin the lithium ions. When a mobile phone is plugged in to be charged, the ions and electrons retrace their steps, and the battery can be used again.

When a battery is charged, however, not all the lithium ions make it back. Every charging cycle leaves ions straggling at the graphite electrode, and the battery loses capacity over time. Das found this perplexing, because it meant that draining a phone’s battery didn’t harm it, but recharging it did. He addressed this conundrum in a couple of open-access academic publications in 2019.

There was also another problem. When a battery is “fast-charged” — a feature that comes with many of the latest electronics — lithium ions start layering (plating) over the carbon electrode, instead of transporting (intercalating) into the material. Prolonged lithium plating can cause uncontrolled growth of fractal-like dendrites. This can cause short-circuiting, even fires.

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In his doctoral research, Das and collaborators have been able to understand the microscopic changes that degrade a battery’s electrodes over its lifetime, and develop multiscale physics-based models to predict them in a robust manner at the macro-scale.

Such multiscale models can aid battery manufacturers to substantially reduce battery health diagnostics costs before it is incorporated into a device, and make batteries safer for consumers. In his latest project, he’s using that knowledge to investigate the best way of charging a lithium-ion battery without damaging it. Das hopes his contributions help scientists achieve further breakthroughs in battery science and make batteries safer, especially when the latest technology is often closely guarded by private companies. “What our group is trying to do is improve the quality of open access academic literature,” Das says. “So that when other people are trying to start their research in batteries, they don’t have to start at the theory from five to 10 years ago.”

Das is well-placed to walk between the worlds of academia and industry.

As an undergraduate in Indian Institute of Technology (IIT) Delhi, Das learned that chemical engineers could use equations and experiments to invent technology like drugs and semi-conductors. “Just the fact that here I was in college, learning something that gave me the power to potentially impact the lives of N number of people in a positive manner, was utterly fascinating to me,” Das says. He also interned at a consumer goods company, where he realized that academia would allow him more freedom to pursue ambitious ideas.

In his sophomore year, Das wrote to a professor at the Hong Kong University of Science and Technology, seeking an opportunity to do research. He flew out that summer, and spent weeks learning about high-power lithium-ion batteries. “It was an eye-opening experience,” Das recalls. He returned to his coursework, but the idea of working on batteries had taken hold. “I never thought that something I can do with my own hands can potentially make impact at the scale that battery technology does,” Das says. He continued working on research projects and made key contributions in the field of multiphase chemical reaction engineering during his undergraduate degree, and eventually wound up applying to the graduate program at MIT.

In his second year of graduate work, Das spent a semester as a technical consultant for Shell in Houston, Texas and Emirates Global Aluminum in Dubai. There, he learned lessons that would prove invaluable in his graduate work. “It taught me problem formulation,” Das says. “Identifying what is relevant for stakeholders; what to work on so as to best use the team’s skill sets; how to distribute your time.”

After Das’s experience in the field, he discovered that as a scientist he could share valuable knowledge about battery research and the future of the technology with energy economists. He also realized that policymakers considered their own criteria when investing in technology for the future.

Das believed that such a perspective would help him inform policy decisions as a scientist, so he decided that after completing his PhD, he would pursue an MBA focusing on energy economics and policy at MIT’s Sloan School of Management. “It will allow me to contribute more to society if I’m able to act as a bridge between someone who understands the hardcore, microscopic physics of a battery, and someone who understands the economic and policy implications of introducing that battery into a vehicle or a grid,” Das says.

Das believes that the program, which begins next fall, will allow him to work with other energy experts who bring their own knowledge and skills to the table. He understands the power of collaboration well: at college, Das was elected president of a dorm of 450-plus residents and worked with students and administration to introduce new facilities and events on campus. After arriving in Cambridge, Massachusetts, Das helped other students manage Ashdown House, represented chemical engineering students on the Graduate Student Advisory Board, and served in the leadership team for the MIT Energy Club, spearheading the organization of MIT EnergyHack 2019.

He also launched a community service initiative within the Department of Chemical Engineering; once a week, students mentor school children and volunteer at nonprofits in Cambridge. He was able to attract funding for his initiative and was awarded by the department for successfully mobilizing 80-plus students in the community within the span of a year. “I’m constantly surprised at what we can achieve when we work with other people,” Das says.

After all, other people have helped Das make it this far. “I owe a lot of success to a number of sacrifices my mom made for me, including giving up her own career,” he says. At MIT, he feels fortunate to have met mentors like his advisor, Martin Bazant, and Practice School directors Robert Fisher and Brian Stutts, and the many colleagues who have offered answers to his questions. “Here, I’ve discovered what it means to synergize with really smart people who are really passionate — and really nice at the same time,” Das says. “Grateful is the one word I’d use.”

MIT: Carbon nanotube transistors make the leap from lab to factory floor


The next major revolution in computer chip technology is now a step closer to reality. Researchers have shown that carbon nanotube transistors can be made rapidly in commercial facilities, with the same equipment used to manufacture traditional silicon-based transistors – the backbone of today’s computing industry. 

Carbon nanotube field-effect transistors (CNFETs) are more energy-efficient than silicon field-effect transistors and could be used to build a new generation of three-dimensional microprocessors. But until now, these devices have been mostly restricted to academic laboratories with only small numbers produced.

However, in a new study this month – published in the journal Nature Electronics – scientists have demonstrated how CNFETs can be fabricated in large quantities on 200-millimetre wafers: the industry standard for computer chip design. The CNFETs were created in a commercial silicon manufacturing facility and a semiconductor foundry in the United States.

Having analysed the deposition technique used to make the CNFETs, a team at the Massachusetts Institute of Technology (MIT) developed a way of speeding up the fabrication process by more than 1,100 times compared to previous methods, while also reducing the cost.

Their technique deposited the carbon nanotubes edge to edge on wafers, with CFNET arrays of 14,400 by 14,400 distributed across multiple wafers.

Max Shulaker, an MIT assistant professor of electrical engineering and computer science, who has been designing CNFETs since his PhD days, says the new study represents “a giant step forward, to make that leap into production-level facilities.”

Bridging the gap between lab and industry is something that researchers “don’t often get a chance to do,” he added. “But it’s an important litmus test for emerging technologies.”

 

 

For decades, improvements in silicon-based transistor manufacturing have brought down prices and increased energy efficiency in computing. Concerns are mounting that this trend may be nearing its end, however, as increasing numbers of transistors packed into integrated circuits do not appear to be increasing energy efficiency at historic rates. CNFETs are an attractive alternative technology because they are “around an order of magnitude more energy efficient” than silicon-based transistors, says Shulaker.

While silicon-based transistors are typically made at temperatures of 450 to 500 degrees Celsius, CNFETs can be manufactured at near-room temperatures.

“This means that you can actually build layers of circuits right on top of previously fabricated layers of circuits, to create a 3D chip,” Shulaker explains. “You can’t do this with silicon-based technology, because it would melt the layers underneath.” 

A 3D computer chip, which might combine logic and memory functions, is projected to “beat the performance of a state-of-the-art 2D chip made from silicon by orders of magnitude,” he says.

One of the most effective ways to build CFNETs in the lab is a method for depositing nanotubes called incubation – illustrated below – where a wafer is submerged in a bath of nanotubes until the nanotubes stick to the wafer’s surface.

The performance of the CNFET depends in large part on the deposition process, explains co-author Mindy Bishop, a PhD student in the Harvard-MIT Health Sciences and Technology program. This affects both the number of carbon nanotubes on the surface of the wafer and their orientation. They are “either stuck onto the wafer in random orientations like cooked spaghetti, or all aligned in the same direction like uncooked spaghetti still in the package.”

Aligning the nanotubes perfectly in a CNFET leads to ideal performance, but alignment is difficult to obtain, says Bishop: “It’s really hard to lay down billions of tiny 1-nanometre diameter nanotubes in a perfect orientation across a large 200-millimetre wafer. To put these length scales into context, it’s like trying to cover the entire state of New Hampshire in perfectly oriented, dry spaghetti.” 

While the incubation method employed by the MIT team is unable to perfectly align every nanotube (perhaps a breakthrough in future years may achieve this?), their experiments showed that it delivers sufficiently high performance for a CNFET to outperform a traditional silicon-based transistor. 

Furthermore, careful observations revealed how to alter the process to make it more viable for large-scale commercial production. For instance, Bishop’s team found that “dry cycling”, a method of intermittently drying out the submerged wafer, could drastically reduce the incubation time – from 48 hours to 150 seconds. Another new method called artificial concentration through evaporation (ACE) deposited small amounts of nanotube solution on a wafer, instead of submerging the wafer in a tank. The slow evaporation of the solution increased the overall density of nanotubes on the wafer. 

The researchers worked with Analog Devices, a commercial silicon manufacturing facility, and SkyWater Technology, a semiconductor foundry, to fabricate CNFETs using the improved methods. They were able to use the same equipment that the two facilities use to make silicon-based wafers, while also ensuring that the nanotube solutions met strict chemical and contaminant requirements of the facilities. 

The next steps, already underway, will be to build different types of integrated circuits out of CNFETs in an industrial setting and explore some of the new functions that a 3D chip could offer, adds Shulaker. 

“The next goal is for this to transition from being academically interesting to something that will be used by folks, and I think this is a very important step in this direction,” he concludes.

Covid-19 Diagnostic Based on MIT Technology to be Tested on Patients Soon


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This scanning electron microscope image shows SARS-CoV-2 (yellow)—also known as 2019-nCoV, the virus that causes COVID-19—isolated from a patient, emerging from the surface of cells (blue/pink) cultured in the lab. Image: NIAID-RML

A variety of MIT research projects could aid efforts to detect and prevent the spread of coronavirus.

As more Covid-19 cases appear in the United States and around the world, the need for fast, easy-to-use diagnostic tests is becoming ever more pressing. A startup company spun out from MIT is now working on a paper-based test that can deliver results in under half an hour, based on technology developed at MIT’s Institute for Medical Engineering and Science (IMES).

Cambridge-based E25Bio, which developed the test, is now preparing to submit it to the FDA for “emergency use authorization,” which would grant temporary approval for using the device on patient samples during public health emergencies.

Elsewhere around MIT, several other research groups are working on projects that may help further scientists’ understanding of how coronaviruses are transmitted and how infection may be prevented. Their work touches on fields ranging from diagnostics and vaccine development to more traditional disease prevention measures such as social distancing and handwashing.

Faster diagnosis

The technology behind the new E25Bio diagnostic was developed by Lee Gehrke, the Hermann L.F. von Helmholtz Professor at IMES, and other members of his lab, including Irene Bosch, a former IMES research scientist who is now the CTO of E25Bio.

For the past several years, Gehrke, Bosch, and others in the lab have been working on diagnostic devices that work similar to a pregnancy test but can identify viral proteins from patient samples. The researchers have used this technology, known as lateral flow technology, to create tests for Ebola, dengue fever, and Zika virus, among other infectious diseases.

The tests consist of strips of paper that are coated with antibodies that bind to a specific viral protein. A second antibody is attached to specialized nanoparticles, and the patient’s sample is added to a solution of those particles. The test strip is then dipped in this solution. If the viral protein is present, it attaches to the antibodies on the paper strip as well as the nanoparticle-bound antibodies, and a colored spot appears on the strip within 20 minutes.

Currently, there are two primary types of Covid-19 diagnostics available. One such test screens patient blood samples for antibodies against the virus. However, antibodies are often not detectable until a few days after symptoms begin. Another type of test looks for viral DNA in a sputum sample. These tests can detect the virus earlier in the infection, but they require polymerase chain reaction (PCR), a technology that amplifies the amount of DNA to detectable levels and takes several hours to perform.

“Our hope is that, similar to other tests that we’ve developed, this will be usable on the day that symptoms develop,” Gehrke says. “We don’t have to wait for antibodies to the virus to come up.”

If the U.S. Food and Drug Administration grants the emergency authorization, E25Bio could start testing the diagnostic with patient samples, which they haven’t been able to do yet. “If those are successful, then the next step would be to talk about using it for actual clinical diagnosis,” Gehrke says.

Another advantage of this approach is that the paper tests can be easily and inexpensively manufactured in large quantities, he adds.

RNA vaccines

On Feb. 24, only about a month after the first U.S. case of coronavirus was reported, the Cambridge-based biotech company Moderna announced it had an experimental vaccine ready to test. That speedy turnaround is due to the unique advantages of RNA vaccines, says Daniel Anderson, an MIT professor of chemical engineering, who also works on such vaccines, though not specifically for coronavirus.

“A key advantage of messenger RNA is the speed with which you can identify a new sequence and use it to come up with a new vaccine,” Anderson says.

Traditional vaccines consist of an inactivated form of a viral protein that induces an immune response. However, these vaccines usually take a long time to manufacture, and for some diseases, they are too risky. Vaccines that consist of messenger RNA are an appealing alternative because they induce host cells to produce many copies of the proteins they encode, provoking a stronger immune response than proteins delivered on their own.

RNA vaccines can also be quickly reprogrammed to target different viral proteins, as long as the sequence encoding the protein is known. The main obstacle to developing such vaccines so far has been finding effective and safe ways to deliver them. Anderson’s lab has been working on such strategies for several years, and in a recent study he showed that packing such vaccines into a special type of lipid nanoparticles can enhance the immune response that they produce.

“Messenger RNA can encode the viral antigens, but in order to work, we need to find a way to deliver these antigens to the correct part of the body so that they get expressed and generate an immune response. We also need to make sure that the vaccine causes appropriate immune stimulation to get a strong response,” Anderson says.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), has estimated that it will take at least 12 to 18 months to fully test any potential Covid-19 vaccine for safety and effectiveness.

Keep your distance

Over the last decade, Lydia Bourouiba, an associate professor directing the Fluid Dynamics of Disease Transmission Laboratory at MIT, has focused on characterizing and modeling infectious disease dynamics and transmission at various scales. Through experiments in the lab and clinical environment, she has reported that when a person coughs or sneezes, they do not emit a spray of individual droplets that quickly fall to the ground and evaporate, as scientists had once thought. Instead, they produce a complex cloud of hot and moist air that traps droplets of all sizes together, propelling them much further through the air than any individual droplet would travel on its own.

On average, her experiments have revealed that a cough can transmit droplets up to 13 to 16 feet, while a sneeze can eject them up to 26 feet away. Surrounding air conditions can act to further disperse the residual droplets in upper levels of rooms.

Bourouiba notes that the presence of the high-speed gas cloud is independent of the type of organism or pathogen that the cloud may contain. The droplets within it depend on pathogenesis coupled with a patient’s physiology — a combination which her laboratory has focused on deciphering in the context of influenza. She is now expanding her studies and modeling to translate the work to Covid-19, and says now is a critical time to invest in research.

“This virus is going to stay with us for a while — and certainly data suggest that it is not going to suddenly disappear when the weather changes,” she says. “There’s a fine and important balance between safety, precautions and action that is important to strike to enable and dramatically accelerate research to be done now so we can be better prepared and informed for actions in the weeks and months to come when the worst of the pandemic will unfold.”

She is also working with others to evaluate ways to limit a cloud’s dispersal and slow Covid-19 transmission to health care workers and others in shared spaces. “A surgical mask is not protective against inhalation of a pathogen from the cloud,” she says. “For an infected patient wearing it, it can contain some of the forward ejecta from coughs or sneezes, but these are very violent ejections and masks are completely open on all sides, and fluid flows through the path of least resistance.”

Based on the data, she recommends that health care workers consider wearing a respirator, whenever possible. And, for the general public, Bourouiba emphasizes that the risk of contracting COVID-19 remains relatively low locally, and that risk should be thought of in the context of the community.

Wash those hands

Another good way to protect yourself against all of those tiny infectious droplets is to wash your hands. (Again, and again, and again.)

Ruben Juanes, an MIT professor of civil and environmental engineering, and of earth, atmospheric and planetary sciences, published a study in December showing the importance of improving rates of handwashing at key airports in order to curtail the spread of an epidemic. Now, he says, following the Covid-19 outbreak, governments around the world have imposed unprecedented restrictions on mobility, including the closure of airports and suspension of flight routes.

At the same time, the World Health Organization, U.S. Centers for Disease Control, and many other health agencies all recommend hand-hygiene as the number one precaution measure against disease spread. “Following our recent paper on the impact of hand-hygiene on global disease spreading,” Juanes says, “we are now investigating the combined effect of restrictions on human mobility and enhanced engagement with hand-hygiene on the global spread of COVID-19 through the world air-transportation network.”

Juanes says he and Christos Nicolaides PhD ’14, a professor at the University of Cyprus who was the lead author of the previous study, are working “with fine-grained, worldwide air-traffic data that accounts for all flights for the period between Jan. 15, 2020 until today (accounting for closures/cancellations) and the corresponding period of 2019 (base level) to elucidate the role of travel restrictions on the global spread of Covid-19 through detailed epidemiological modeling.”

“Furthermore,” he adds, “we simulate different hand-hygiene strategies at airports on top of travel restrictions with the goal of proposing an optimal strategy that combines travel restrictions and enhanced hand hygiene, to mitigate the advance of Covid-19 both in the short term (weeks) and the long term (the next flu season).”

Juanes says they will make the results immediately available via medarXiv, while the work follows peer-review in a journal. This would also allow the information to reach other academic and government institutions in a more timely way, he says.

MIT: Researchers Achieve Remote control of Hormone Release Using Magnetic Nanoparticles


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MIT engineers have developed magnetic nanoparticles (shown in white squares) that can stimulate the adrenal gland to produce stress hormones such as adrenaline and cortisol. Credit: Massachusetts Institute of Technology

Abnormal levels of stress hormones such as adrenaline and cortisol are linked to a variety of mental health disorders, including depression and posttraumatic stress disorder (PTSD). MIT researchers have now devised a way to remotely control the release of these hormones from the adrenal gland, using magnetic nanoparticles.

This approach could help scientists to learn more about how  release influences mental health, and could eventually offer a new way to treat hormone-linked disorders, the researchers say.

“We’re looking how can we study and eventually treat stress disorders by modulating peripheral organ function, rather than doing something highly invasive in the central nervous system,” says Polina Anikeeva, an MIT professor of materials science and engineering and of brain and cognitive sciences.

To achieve control over hormone release, Dekel Rosenfeld, an MIT-Technion postdoc in Anikeeva’s group, has developed specialized  that can be injected into the adrenal gland. When exposed to a weak magnetic field, the particles heat up slightly, activating heat-responsive channels that trigger hormone release. This technique can be used to stimulate an organ deep in the body with minimal invasiveness.

Anikeeva and Alik Widge, an assistant professor of psychiatry at the University of Minnesota and a former research fellow at MIT’s Picower Institute for Learning and Memory, are the senior authors of the study. Rosenfeld is the lead author of the paper, which appears today in Science Advances.

Controlling hormones

Anikeeva’s lab has previously devised several novel magnetic nanomaterials, including particles that can release drugs at precise times in specific locations in the body.

In the new study, the research team wanted to explore the idea of treating disorders of the brain by manipulating organs that are outside the central nervous system but influence it through hormone release. One well-known example is the hypothalamic-pituitary-adrenal (HPA) axis, which regulates stress response in mammals. Hormones secreted by the , including cortisol and adrenaline, play important roles in depression, stress, and anxiety.

“Some disorders that we consider neurological may be treatable from the periphery, if we can learn to modulate those local circuits rather than going back to the global circuits in the ,” says Anikeeva, who is a member of MIT’s Research Laboratory of Electronics and McGovern Institute for Brain Research.

As a target to stimulate hormone release, the researchers decided on  that control the flow of calcium into adrenal cells. Those ion channels can be activated by a variety of stimuli, including heat. When calcium flows through the open channels into adrenal cells, the cells begin pumping out hormones. “If we want to modulate the release of those hormones, we need to be able to essentially modulate the influx of calcium into adrenal cells,” Rosenfeld says.

Unlike previous research in Anikeeva’s group, in this study magnetothermal stimulation was applied to modulate the function of cells without artificially introducing any genes.

To stimulate these heat-sensitive channels, which naturally occur in adrenal cells, the researchers designed nanoparticles made of magnetite, a type of iron oxide that forms tiny magnetic crystals about 1/5000 the thickness of a human hair. In rats, they found these particles could be injected directly into the adrenal glands and remain there for at least six months. When the rats were exposed to a weak magnetic field—about 50 millitesla, 100 times weaker than the fields used for magnetic resonance imaging (MRI)—the particles heated up by about 6 degrees Celsius, enough to trigger the calcium channels to open without damaging any surrounding tissue.

The heat-sensitive  that they targeted, known as TRPV1, is found in many sensory neurons throughout the body, including . TRPV1 channels can be activated by capsaicin, the organic compound that gives chili peppers their heat, as well as by temperature. They are found across mammalian species, and belong to a family of many other channels that are also sensitive to heat.

This stimulation triggered a hormone rush—doubling cortisol production and boosting noradrenaline by about 25 percent. That led to a measurable increase in the animals’ heart rates.

Treating stress and pain

The researchers now plan to use this approach to study how hormone release affects PTSD and other disorders, and they say that eventually it could be adapted for treating such disorders. This method would offer a much less invasive alternative to potential treatments that involve implanting a medical device to electrically stimulate hormone release, which is not feasible in organs such as the adrenal glands that are soft and highly vascularized, the researchers say.

Another area where this strategy could hold promise is in the treatment of pain, because heat-sensitive ion channels are often found in pain receptors.

“Being able to modulate pain receptors with this technique potentially will allow us to study pain, control pain, and have some clinical applications in the future, which hopefully may offer an alternative to medications or implants for chronic pain,” Anikeeva says. With further investigation of the existence of TRPV1 in other organs, the technique can potentially be extended to other peripheral organs such as the digestive system and the pancreas.


Explore further

The myth behind adrenal fatigue


More information: Dekel Rosenfeld et al. Transgene-free remote magnetothermal regulation of adrenal hormones, Science Advances (2020). DOI: 10.1126/sciadv.aaz3734

Journal information: Science Advances

MIT: An Experimental Peptide could Block Covid-19


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MIT chemists are testing a protein fragment that may inhibit coronaviruses’ ability to enter human lung cells.

The research described in this article has been published on a preprint server but has not yet been peer-reviewed by scientific or medical experts.

In hopes of developing a possible treatment for Covid-19, a team of MIT chemists has designed a drug candidate that they believe may block coronaviruses’ ability to enter human cells. The potential drug is a short protein fragment, or peptide, that mimics a protein found on the surface of human cells.

The researchers have shown that their new peptide can bind to the viral protein that coronaviruses use to enter human cells, potentially disarming it.

“We have a lead compound that we really want to explore, because it does, in fact, interact with a viral protein in the way that we predicted it to interact, so it has a chance of inhibiting viral entry into a host cell,” says Brad Pentelute, an MIT associate professor of chemistry, who is leading the research team.

The MIT team reported its initial findings in a preprint posted on bioRxiv, an online preprint server, on March 20. They have sent samples of the peptide to collaborators who plan to carry out tests in human cells.

Molecular targeting

Pentelute’s lab began working on this project in early March, after the Cryo-EM structure of the coronavirus spike protein, along with the human cell receptor that it binds to, was published by a research group in China. Coronaviruses, including SARS-CoV-2, which is causing the current Covid-19 outbreak, have many protein spikes protruding from their viral envelope.

Studies of SARS-CoV-2 have also shown that a specific region of the spike protein, known as the receptor binding domain, binds to a receptor called angiotensin-converting enzyme 2 (ACE2). This receptor is found on the surface of many human cells, including those in the lungs. The ACE2 receptor is also the entry point used by the coronavirus that caused the 2002-03 SARS outbreak.

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What Does COVID Mean>

In hopes of developing drugs that could block viral entry, Genwei Zhang, a postdoc in Pentelute’s lab, performed computational simulations of the interactions between the ACE2 receptor and the receptor binding domain of the coronavirus spike protein. These simulations revealed the location where the receptor binding domain attaches to the ACE2 receptor — a stretch of the ACE2 protein that forms a structure called an alpha helix.

“This kind of simulation can give us views of how atoms and biomolecules interact with each other, and which parts are essential for this interaction,” Zhang says. “Molecular dynamics helps us narrow down particular regions that we want to focus on to develop therapeutics.”

The MIT team then used peptide synthesis technology that Pentelute’s lab has previously developed, to rapidly generate a 23-amino acid peptide with the same sequence as the alpha helix of the ACE2 receptor. Their benchtop flow-based peptide synthesis machine can form linkages between amino acids, the buildings blocks of proteins, in about 37 seconds, and it takes less than an hour to generate complete peptide molecules containing up to 50 amino acids.

“We’ve built these platforms for really rapid turnaround, so I think that’s why we’re at this point right now,” Pentelute says. “It’s because we have these tools we’ve built up at MIT over the years.”

They also synthesized a shorter sequence of only 12 amino acids found in the alpha helix, and then tested both of the peptides using equipment at MIT’s Biophysical Instrumentation Facility that can measure how strongly two molecules bind together. They found that the longer peptide showed strong binding to the receptor binding domain of the Covid-19 spike protein, while the shorter one showed negligible binding.

Many variants

Although MIT has been scaling back on-campus research since mid-March, Pentelute’s lab was granted special permission allowing a small group of researchers to continue to work on this project. They are now developing about 100 different variants of the peptide in hopes of increasing its binding strength and making it more stable in the body.

“We have confidence that we know exactly where this molecule is interacting, and we can use that information to further guide refinement, so that we can hopefully get a higher affinity and more potency to block viral entry in cells,” Pentelute says.

In the meantime, the researchers have already sent their original 23-amino acid peptide to a research lab at the Icahn School of Medicine at Mount Sinai for testing in human cells and potentially in animal models of Covid-19 infection.

While dozens of research groups around the world are using a variety of approaches to seek new treatments for Covid-19, Pentelute believes his lab is one of a few currently working on peptide drugs for this purpose. One advantage of such drugs is that they are relatively easy to manufacture in large quantities. They also have a larger surface area than small-molecule drugs.

“Peptides are larger molecules, so they can really grip onto the coronavirus and inhibit entry into cells, whereas if you used a small molecule, it’s difficult to block that entire area that the virus is using,” Pentelute says. “Antibodies also have a large surface area, so those might also prove useful. Those just take longer to manufacture and discover.”

One drawback of peptide drugs is that they typically can’t be taken orally, so they would have to be either administered intravenously or injected under the skin. They would also need to be modified so that they can stay in the bloodstream long enough to be effective, which Pentelute’s lab is also working on.

“It’s hard to project how long it will take to have something we can test in patients, but my aim is to have something within a matter of weeks. If it turns out to be more challenging, it may take months,” he says.

In addition to Pentelute and Zhang, other researchers listed as authors on the preprint are postdoc Sebastian Pomplun, grad student Alexander Loftis, and research scientist Andrei Loas.

MIT and University of Waterloo Lead the Way: Quantum Radar Reliably Demonstrated – Making it useful for Biomedical and Security (Stealth) Applications


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A radar device that relies on entangled photons works at such low power that it can hide behind background noise, making it useful for biomedical and security (stealthy radar) applications.

One of the advantages of the quantum revolution is the ability to sense the world in a new way. The general idea is to use the special properties of quantum mechanics to make measurements or produce images that are otherwise impossible.

Much of this work is done with photons. But as far as the electromagnetic spectrum is concerned, the quantum revolution has been a little one-sided. Almost all the advances in quantum computing, cryptography, teleportation, and so on have involved visible or near-visible light.

Today that changes thanks to the work of Shabir Barzanjeh at the Institute of Science and Technology Austria and a few colleagues. This team has used entangled microwaves to create the world’s first quantum radar. Their device, which can detect objects at a distance using only a few photons, raises the prospect of stealthy radar systems that emit little detectable electromagnetic radiation.

The device is simple in essence. The researchers create pairs of entangled microwave photons using a superconducting device called a Josephson parametric converter. They beam the first photon, called the signal photon, toward the object of interest and listen for the reflection.

Quantum radar

In the meantime, they store the second photon, called the idler photon. When the reflection arrives, it interferes with this idler photon, creating a signature that reveals how far the signal photon has traveled. Voila—quantum radar!

This technique has some important advantages over conventional radar. Ordinary radar works in a similar way but fails at low power levels that involve small numbers of microwave photons. That’s because hot objects in the environment emit microwaves of their own.

In a room temperature environment, this amounts to a background of around 1,000 microwave photons at any instant, and these overwhelm the returning echo. This is why radar systems use powerful transmitters.

Entangled photons overcome this problem. The signal and idler photons are so similar that it is easy to filter out the effects of other photons. So it becomes straightforward to detect the signal photon when it returns.

Of course, entanglement is a fragile property of the quantum world, and the process of reflection destroys it.  Nevertheless, the correlation between the signal and idler photons is still strong enough to distinguish them from background noise.

This allows Barzanjeh and co to detect a room temperature object in a room temperature environment with just a handful of photons, in a way that is impossible to do with ordinary photons. “We generate entangled fields using a Josephson parametric converter at millikelvin temperatures to illuminate a room-temperature object at a distance of 1 meter in a proof of principle radar setup,” they say.

The researchers go on to compare their quantum radar with conventional systems operating with similarly low numbers of photons and say it significantly outperforms them, albeit only over relatively short distances.

That’s interesting work revealing the significant potential of quantum radar and a first application of microwave-based entanglement. But it also shows the potential application of quantum illumination more generally.

 

A big advantage is the low levels of electromagnetic radiation required. “Our experiment shows the potential as a non-invasive scanning method for biomedical applications, e.g., for imaging of human tissues or non-destructive rotational spectroscopy of proteins,” say Barzanjeh and co.

Then there is the obvious application as a stealthy radar that is difficult for adversaries to detect over background noise. The researchers say it could be useful for short-range low-power radar for security applications in closed and populated environments.

quantum radar 2 2018-05-14-s20_quantuim_radar_stealth_aircraft_entanglement_canada

Ref: arxiv.org/abs/1908.03058 : Experimental Microwave Quantum Illumination

University of Waterloo Leads The Way in Canada

Waterloo Institute for Nanotechnology (WIN) members, in Professor Zbig Wasilewski partnership with the Institute for Quantum Computing (IQC), is developing the next generation of radar, quantum radar. Professor Zbig Wasilewski, from the Department of Electrical and Computer Engineering, is fabricating the materials for quantum radar.

The two other co-PIs on this project are Professor Jonathan Baugh and Professor Mike Reimer. Professor Baugh is a member of both WIN and IQC, while Professor Reimer main focus is on quantum photonics as a member of IQC.

In April 2018, the Government of Canada announced they would invest $2.7 million in the joint quantum radar project. The state-ofthe-art facilities in Lazaridis Centre make this project possible. Professor Wasilewski’s Molecular Beam Epitaxy (MBE) lab will grow the quantum material to adequate perfection to meet the challenge. The IQC houses the necessary quantum device processing and photonic labs. This ambitious project is not possible at many research institutions in the world. The MBE lab allows Wasilewski to create quantum structures with atomic precision. These materials will in turn form the foundation of the quantum radar. “Many challenges lie ahead,” said Professor Wasilewski. “Building up quantum illumination sources to the scale needed for quantum radar calls for the very best in material growth, nanofabrication and quantum engineering. We have an excellent interdisciplinary team with the diverse expertise needed to tackle all these challenges. It would be hard to assemble a better one in Canada or internationally.”

quantum_radar 1

“We have an excellent interdisciplinary team with the diverse expertise needed to tackle all these challenges. It would be hard to assemble a better one in Canada or internationally.”

– Professor Zbig Wasilewski, Department of Electrical and Computer Engineering, University of Waterloo

Professor Jonathan Baugh said, “By developing a fast, on-demand source of quantum light, we hope to bring techniques like quantum illumination from the lab to the real world. This project would not be possible without the right team, and we are fortunate to have a uniquely strong multidisciplinary collaboration based entirely at Waterloo, one which strengthens ties between WIN and IQC.”

The proposed quantum radar will help operators cut through heavy background noise and isolate objects in Canada’s far north. Standard radar systems are unable to detect stealth aircraft in the high-arctic due to the aurora borealis. This natural phenomenon sends electromagnetic energy at varying wavelengths down to Earth.

It is hypothesized that quantum radar works by separating two entangled light particles. You keep one on earth and send the entangled partner into the sky. If the light particle bounces off of your source and back to your detector you have located a stealth aircraft.

Quantum radar’s viability outside of a lab still needs to be determined. The goal of this project is to demonstrate its capability in the field.

The $2.7 million is being invested under the Department of National Defence’s All Domain Situational Awareness (ADSA) Science and Technology program.

MIT – Researchers develop a roadmap for growth of new solar cells – Could become Competitive with Silicon


MIT-Scaling-Perovskite_0Perovskites, a family of materials defined by a particular kind of molecular structure as illustrated here, have great potential for new kinds of solar cells. A new study from MIT shows how these materials could gain a foothold in the solar marketplace. Image: Christine Daniloff, MIT

Starting with higher-value niche markets and then expanding could help perovskite-based solar panels become competitive with silicon

Materials called perovskites show strong potential for a new generation of solar cells, but they’ve had trouble gaining traction in a market dominated by silicon-based solar cells. Now, a study by researchers at MIT and elsewhere outlines a roadmap for how this promising technology could move from the laboratory to a significant place in the global solar market.

The “technoeconomic” analysis shows that by starting with higher-value niche markets and gradually expanding, solar panel manufacturers could avoid the very steep initial capital costs that would be required to make perovskite-based panels directly competitive with silicon for large utility-scale installations at the outset. Rather than making a prohibitively expensive initial investment, of hundreds of millions or even billions of dollars, to build a plant for utility-scale production, the team found that starting with more specialized applications could be accomplished for more realistic initial capital investment on the order of $40 million.

The results are described in a paper in the journal Joule by MIT postdoc Ian Mathews, research scientist Marius Peters, professor of mechanical engineering Tonio Buonassisi, and five others at MIT, Wellesley College, and Swift Solar Inc.

Solar cells based on perovskites — a broad category of compounds characterized by a certain arrangement of their molecular structure — could provide dramatic improvements in solar installations. Their constituent materials are inexpensive, and they could be manufactured in a roll-to-roll process like printing a newspaper, and printed onto lightweight and flexible backing material. This could greatly reduce costs associated with transportation and installation, although they still require further work to improve their durability. Other promising new solar cell materials are also under development in labs around the world, but none has yet made inroads in the marketplace.

“There have been a lot of new solar cell materials and companies launched over the years,” says Mathews, “and yet, despite that, silicon remains the dominant material in the industry and has been for decades.”

Why is that the case? “People have always said that one of the things that holds new technologies back is that the expense of constructing large factories to actually produce these systems at scale is just too much,” he says. “It’s difficult for a startup to cross what’s called ‘the valley of death,’ to raise the tens of millions of dollars required to get to the scale where this technology might be profitable in the wider solar energy industry.”

But there are a variety of more specialized solar cell applications where the special qualities of perovskite-based solar cells, such as their light weight, flexibility, and potential for transparency, would provide a significant advantage, Mathews says. By focusing on these markets initially, a startup solar company could build up to scale gradually, leveraging the profits from the premium products to expand its production capabilities over time.

Describing the literature on perovskite-based solar cells being developed in various labs, he says, “They’re claiming very low costs. But they’re claiming it once your factory reaches a certain scale. And I thought, we’ve seen this before — people claim a new photovoltaic material is going to be cheaper than all the rest and better than all the rest. That’s great, except we need to have a plan as to how we actually get the material and the technology to scale.”

As a starting point, he says, “We took the approach that I haven’t really seen anyone else take: Let’s actually model the cost to manufacture these modules as a function of scale. So if you just have 10 people in a small factory, how much do you need to sell your solar panels at in order to be profitable? And once you reach scale, how cheap will your product become?”

The analysis confirmed that trying to leap directly into the marketplace for rooftop solar or utility-scale solar installations would require very large upfront capital investment, he says. But “we looked at the prices people might get in the internet of things, or the market in building-integrated photovoltaics. People usually pay a higher price in these markets because they’re more of a specialized product. They’ll pay a little more if your product is flexible or if the module fits into a building envelope.” Other potential niche markets include self-powered microelectronics devices.

Such applications would make the entry into the market feasible without needing massive capital investments. “If you do that, the amount you need to invest in your company is much, much less, on the order of a few million dollars instead of tens or hundreds of millions of dollars, and that allows you to more quickly develop a profitable company,” he says.

“It’s a way for them to prove their technology, both technically and by actually building and selling a product and making sure it survives in the field,” Mathews says, “and also, just to prove that you can manufacture at a certain price point.”

Already, there are a handful of startup companies working to try to bring perovskite solar cells to market, he points out, although none of them yet has an actual product for sale. The companies have taken different approaches, and some seem to be embarking on the kind of step-by-step growth approach outlined by this research, he says. “Probably the company that’s raised the most money is a company called Oxford PV, and they’re looking at tandem cells,” which incorporate both silicon and perovskite cells to improve overall efficiency. Another company is one started by Joel Jean PhD ’17 (who is also a co-author of this paper) and others, called Swift Solar, which is working on flexible perovskites. And there’s a company called Saule Technologies, working on printable perovskites.

Mathews says the kind of technoeconomic analysis the team used in its study could be applied to a wide variety of other new energy-related technologies, including rechargeable batteries and other storage systems, or other types of new solar cell materials.

“There are many scientific papers and academic studies that look at how much it will cost to manufacture a technology once it’s at scale,” he says. “But very few people actually look at how much does it cost at very small scale, and what are the factors affecting economies of scale? And I think that can be done for many technologies, and it would help us accelerate how we get innovations from lab to market.”

The research team also included MIT alumni Sarah Sofia PhD ’19 and Sin Cheng Siah PhD ’15, Wellesley College student Erica Ma, and former MIT postdoc Hannu Laine. The work was supported by the European Union’s Horizon 2020 research and innovation program, the Martin Family Society for Fellows of Sustainability, the U.S. Department of Energy, Shell, through the MIT Energy Initiative, and the Singapore-MIT Alliance for Research and Technology.

MIT – A Simple, Solar-Powered Water Desalination System


MIT-Portable-Desalination_1Tests on an MIT building rooftop showed that a simple proof-of-concept desalination device could produce clean, drinkable water at a rate equivalent to more than 1.5 gallons per hour for each square meter of solar collecting area. Images courtesy of the researchers

System achieves new level of efficiency in harnessing sunlight to make fresh potable water from seawater.

A completely passive solar-powered desalination system developed by researchers at MIT and in China could provide more than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. Such systems could potentially serve off-grid arid coastal areas to provide an efficient, low-cost water source.

The system uses multiple layers of flat solar evaporators and condensers, lined up in a vertical array and topped with transparent aerogel insulation. It is described in a paper appearing today in the journal Energy and Environmental Science, authored by MIT doctoral students Lenan Zhang and Lin Zhao, postdoc Zhenyuan Xu, professor of mechanical engineering and department head Evelyn Wang, and eight others at MIT and at Shanghai Jiao Tong University in China.

The key to the system’s efficiency lies in the way it uses each of the multiple stages to desalinate the water. At each stage, heat released by the previous stage is harnessed instead of wasted. In this way, the team’s demonstration device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation.

The device is essentially a multilayer solar still, with a set of evaporating and condensing components like those used to distill liquor. It uses flat panels to absorb heat and then transfer that heat to a layer of water so that it begins to evaporate. The vapor then condenses on the next panel. That water gets collected, while the heat from the vapor condensation gets passed to the next layer.

Whenever vapor condenses on a surface, it releases heat; in typical condenser systems, that heat is simply lost to the environment. But in this multilayer evaporator the released heat flows to the next evaporating layer, recycling the solar heat and boosting the overall efficiency.

“When you condense water, you release energy as heat,” Wang says. “If you have more than one stage, you can take advantage of that heat.”

Adding more layers increases the conversion efficiency for producing potable water, but each layer also adds cost and bulk to the system. The team settled on a 10-stage system for their proof-of-concept device, which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 liters per square meter (about 1.52 gallons per 11 square feet) of solar collecting area. This is more than two times as much as the record amount previously produced by any such passive solar-powered desalination system, Wang says.

Theoretically, with more desalination stages and further optimization, such systems could reach overall efficiency levels as high as 700 or 800 percent, Zhang says.

Unlike some desalination systems, there is no accumulation of salt or concentrated brines to be disposed of. In a free-floating configuration, any salt that accumulates during the day would simply be carried back out at night through the wicking material and back into the seawater, according to the researchers.

Their demonstration unit was built mostly from inexpensive, readily available materials such as a commercial black solar absorber and paper towels for a capillary wick to carry the water into contact with the solar absorber. In most other attempts to make passive solar desalination systems, the solar absorber material and the wicking material have been a single component, which requires specialized and expensive materials, Wang says. “We’ve been able to decouple these two.”

The most expensive component of the prototype is a layer of transparent aerogel used as an insulator at the top of the stack, but the team suggests other less expensive insulators could be used as an alternative. (The aerogel itself is made from dirt-cheap silica but requires specialized drying equipment for its manufacture.)

Wang emphasizes that the team’s key contribution is a framework for understanding how to optimize such multistage passive systems, which they call thermally localized multistage desalination. The formulas they developed could likely be applied to a variety of materials and device architectures, allowing for further optimization of systems based on different scales of operation or local conditions and materials.

One possible configuration would be floating panels on a body of saltwater such as an impoundment pond. These could constantly and passively deliver fresh water through pipes to the shore, as long as the sun shines each day. Other systems could be designed to serve a single household, perhaps using a flat panel on a large shallow tank of seawater that is pumped or carried in. The team estimates that a system with a roughly 1-square-meter solar collecting area could meet the daily drinking water needs of one person. In production, they think a system built to serve the needs of a family might be built for around $100.

The researchers plan further experiments to continue to optimize the choice of materials and configurations, and to test the durability of the system under realistic conditions. They also will work on translating the design of their lab-scale device into a something that would be suitable for use by consumers. The hope is that it could ultimately play a role in alleviating water scarcity in parts of the developing world where reliable electricity is scarce but seawater and sunlight are abundant.

“This new approach is very significant,” says Ravi Prasher, an associate lab director at

Lawrence Berkeley National Laboratory and adjunct professor of mechanical engineering at the University of California at Berkeley, who was not involved in this work. “One of the challenges in solar still-based desalination has been low efficiency due to the loss of significant energy in condensation. By efficiently harvesting the condensation energy, the overall solar to vapor efficiency is dramatically improved. … This increased efficiency will have an overall impact on reducing the cost of produced water.”

The research team included Bangjun Li, Chenxi Wang and Ruzhu Wang at the Shanghai Jiao Tong University, and Bikram Bhatia, Kyle Wilke, Youngsup Song, Omar Labban, and John Lienhard, who is the Abdul Latif Jameel Professor of Water at MIT. The research was supported by the National Natural Science Foundation of China, the Singapore-MIT Alliance for Research and Technology, and the MIT Tata Center for Technology and Design.

MIT – A new approach to making airplane parts, minus the massive infrastructure


MIT-Nano-plugs-PRESS-01

Carbon nanotube film produces aerospace-grade composites with no need for huge ovens or autoclaves.

A modern airplane’s fuselage is made from multiple sheets of different composite materials, like so many layers in a phyllo-dough pastry. Once these layers are stacked and molded into the shape of a fuselage, the structures are wheeled into warehouse-sized ovens and autoclaves, where the layers fuse together to form a resilient, aerodynamic shell.

Now MIT engineers have developed a method to produce aerospace-grade composites without the enormous ovens and pressure vessels. The technique may help to speed up the manufacturing of airplanes and other large, high-performance composite structures, such as blades for wind turbines.

The researchers detail their new method in a paper published today in the journal Advanced Materials Interfaces.

“If you’re making a primary structure like a fuselage or wing, you need to build a pressure vessel, or autoclave, the size of a two- or three-story building, which itself requires time and money to pressurize,” says Brian Wardle, professor of aeronautics and astronautics at MIT. “These things are massive pieces of infrastructure. Now we can make primary structure materials without autoclave pressure, so we can get rid of all that infrastructure.”

Wardle’s co-authors on the paper are lead author and MIT postdoc Jeonyoon Lee, and Seth Kessler of Metis Design Corporation, an aerospace structural health monitoring company based in Boston.

Out of the oven, into a blanket

In 2015, Lee led the team, along with another member of Wardle’s lab, in creating a method to make aerospace-grade composites without requiring an oven to fuse the materials together. Instead of placing layers of material inside an oven to cure, the researchers essentially wrapped them in an ultrathin film of carbon nanotubes (CNTs). When they applied an electric current to the film, the CNTs, like a nanoscale electric blanket, quickly generated heat, causing the materials within to cure and fuse together.

With this out-of-oven, or OoO, technique, the team was able to produce composites as strong as the materials made in conventional airplane manufacturing ovens, using only 1 percent of the energy.

The researchers next looked for ways to make high-performance composites without the use of large, high-pressure autoclaves — building-sized vessels that generate high enough pressures to press materials together, squeezing out any voids, or air pockets, at their interface.

“There’s microscopic surface roughness on each ply of a material, and when you put two plys together, air gets trapped between the rough areas, which is the primary source of voids and weakness in a composite,” Wardle says. “An autoclave can push those voids to the edges and get rid of them.”

Researchers including Wardle’s group have explored “out-of-autoclave,” or OoA, techniques to manufacture composites without using the huge machines. But most of these techniques have produced composites where nearly 1 percent of the material contains voids, which can compromise a material’s strength and lifetime. In comparison, aerospace-grade composites made in autoclaves are of such high quality that any voids they contain are neglible and not easily measured.

“The problem with these OoA approaches is also that the materials have been specially formulated, and none are qualified for primary structures such as wings and fuselages,” Wardle says. “They’re making some inroads in secondary structures, such as flaps and doors, but they still get voids.”

Straw pressure

Part of Wardle’s work focuses on developing nanoporous networks — ultrathin films made from aligned, microscopic material such as carbon nanotubes, that can be engineered with exceptional properties, including color, strength, and electrical capacity. The researchers wondered whether these nanoporous films could be used in place of giant autoclaves to squeeze out voids between two material layers, as unlikely as that may seem.

A thin film of carbon nanotubes is somewhat like a dense forest of trees, and the spaces between the trees can function like thin nanoscale tubes, or capillaries. A capillary such as a straw can generate pressure based on its geometry and its surface energy, or the material’s ability to attract liquids or other materials.

The researchers proposed that if a thin film of carbon nanotubes were sandwiched between two materials, then, as the materials were heated and softened, the capillaries between the carbon nanotubes should have a surface energy and geometry such that they would draw the materials in toward each other, rather than leaving a void between them. Lee calculated that the capillary pressure should be larger than the pressure applied by the autoclaves.

The researchers tested their idea in the lab by growing films of vertically aligned carbon nanotubes using a technique they previously developed, then laying the films between layers of materials that are typically used in the autoclave-based manufacturing of primary aircraft structures. They wrapped the layers in a second film of carbon nanotubes, which they applied an electric current to to heat it up. They observed that as the materials heated and softened in response, they were pulled into the capillaries of the intermediate CNT film.

The resulting composite lacked voids, similar to aerospace-grade composites that are produced in an autoclave. The researchers subjected the composites to strength tests, attempting to push the layers apart, the idea being that voids, if present, would allow the layers to separate more easily.

“In these tests, we found that our out-of-autoclave composite was just as strong as the gold-standard autoclave process composite used for primary aerospace structures,” Wardle says.

The team will next look for ways to scale up the pressure-generating CNT film. In their experiments, they worked with samples measuring several centimeters wide — large enough to demonstrate that nanoporous networks can pressurize materials and prevent voids from forming. To make this process viable for manufacturing entire wings and fuselages, researchers will have to find ways to manufacture CNT and other nanoporous films at a much larger scale.

“There are ways to make really large blankets of this stuff, and there’s continuous production of sheets, yarns, and rolls of material that can be incorporated in the process,” Wardle says.

He plans also to explore different formulations of nanoporous films, engineering capillaries of varying surface energies and geometries, to be able to pressurize and bond other high-performance materials.

“Now we have this new material solution that can provide on-demand pressure where you need it,” Wardle says. “Beyond airplanes, most of the composite production in the world is composite pipes, for water, gas, oil, all the things that go in and out of our lives. This could make making all those things, without the oven and autoclave infrastructure.”

This research was supported, in part, by Airbus, ANSYS, Embraer, Lockheed Martin, Saab AB, Saertex, and Teijin Carbon America through MIT’s Nano-Engineered Composite aerospace Structures (NECST) Consortium.

MIT – A new way to deliver drugs with pinpoint targeting


MIT-Nanomaterial-Drug-Delivery-01_0

Diagram illustrates the structure of the tiny bubbles, called liposomes, used to deliver drugs. The blue spheres represent lipids, a kind of fat molecule, surrounding a central cavity containing magnetic nanoparticles (black) and the drug to be delivered (red). When the nanoparticles are heated, the drug can escape into the body. Image courtesy of the researchers

Magnetic particles allow drugs to be released at precise times and in specific areas.

Most pharmaceuticals must either be ingested or injected into the body to do their work. Either way, it takes some time for them to reach their intended targets, and they also tend to spread out to other areas of the body. Now, researchers at MIT and elsewhere have developed a system to deliver medical treatments that can be released at precise times, minimally-invasively, and that ultimately could also deliver those drugs to specifically targeted areas such as a specific group of neurons in the brain.

The new approach is based on the use of tiny magnetic particles enclosed within a tiny hollow bubble of lipids (fatty molecules) filled with water, known as a liposome. The drug of choice is encapsulated within these bubbles, and can be released by applying a magnetic field to heat up the particles, allowing the drug to escape from the liposome and into the surrounding tissue.

The findings are reported today in the journal Nature Nanotechnology in a paper by MIT postdoc Siyuan Rao, Associate Professor Polina Anikeeva, and 14 others at MIT, Stanford University, Harvard University, and the Swiss Federal Institute of Technology in Zurich.

“We wanted a system that could deliver a drug with temporal precision, and could eventually target a particular location,” Anikeeva explains. “And if we don’t want it to be invasive, we need to find a non-invasive way to trigger the release.”

Magnetic fields, which can easily penetrate through the body — as demonstrated by detailed internal images produced by magnetic resonance imaging, or MRI — were a natural choice. The hard part was finding materials that could be triggered to heat up by using a very weak magnetic field (about one-hundredth the strength of that used for MRI), in order to prevent damage to the drug or surrounding tissues, Rao says.

Rao came up with the idea of taking magnetic nanoparticles, which had already been shown to be capable of being heated by placing them in a magnetic field, and packing them into these spheres called liposomes. These are like little bubbles of lipids, which naturally form a spherical double layer surrounding a water droplet.

When placed inside a high-frequency but low-strength magnetic field, the nanoparticles heat up, warming the lipids and making them undergo a transition from solid to liquid, which makes the layer more porous — just enough to let some of the drug molecules escape into the surrounding areas. When the magnetic field is switched off, the lipids re-solidify, preventing further releases. Over time, this process can be repeated, thus releasing doses of the enclosed drug at precisely controlled intervals.

The drug carriers were engineered to be stable inside the body at the normal body temperature of 37 degrees Celsius, but able to release their payload of drugs at a temperature of 42 degrees. “So we have a magnetic switch for drug delivery,” and that amount of heat is small enough “so that you don’t cause thermal damage to tissues,” says Anikeeva, who holds appointments in the departments of Materials Science and Engineering and the Brain and Cognitive Sciences.

In principle, this technique could also be used to guide the particles to specific, pinpoint locations in the body, using gradients of magnetic fields to push them along, but that aspect of the work is an ongoing project. For now, the researchers have been injecting the particles directly into the target locations, and using the magnetic fields to control the timing of drug releases. “The technology will allow us to address the spatial aspect,” Anikeeva says, but that has not yet been demonstrated.

This could enable very precise treatments for a wide variety of conditions, she says. “Many brain disorders are characterized by erroneous activity of certain cells. When neurons are too active or not active enough, that manifests as a disorder, such as Parkinson’s, or depression, or epilepsy.” If a medical team wanted to deliver a drug to a specific patch of neurons and at a particular time, such as when an onset of symptoms is detected, without subjecting the rest of the brain to that drug, this system “could give us a very precise way to treat those conditions,” she says.

Rao says that making these nanoparticle-activated liposomes is actually quite a simple process. “We can prepare the liposomes with the particles within minutes in the lab,” she says, and the process should be “very easy to scale up” for manufacturing. And the system is broadly applicable for drug delivery: “we can encapsulate any water-soluble drug,” and with some adaptations, other drugs as well, she says.

One key to developing this system was perfecting and calibrating a way of making liposomes of a highly uniform size and composition. This involves mixing a water base with the fatty acid lipid molecules and magnetic nanoparticles and homogenizing them under precisely controlled conditions. Anikeeva compares it to shaking a bottle of salad dressing to get the oil and vinegar mixed, but controlling the timing, direction and strength of the shaking to ensure a precise mixing.

Anikeeva says that while her team has focused on neurological disorders, as that is their specialty, the drug delivery system is actually quite general and could be applied to almost any part of the body, for example to deliver cancer drugs, or even to deliver painkillers directly to an affected area instead of delivering them systemically and affecting the whole body. “This could deliver it to where it’s needed, and not deliver it continuously,” but only as needed.

Because the magnetic particles themselves are similar to those already in widespread use as contrast agents for MRI scans, the regulatory approval process for their use may be simplified, as their biological compatibility has largely been proven.

The team included researchers in MIT’s departments of Materials Science and Engineering and Brain and Cognitive Sciences, as well as the McGovern Institute for Brain Research, the Simons Center for Social Brain, and the Research Laboratory of Electronics; the Harvard University Department of Chemistry and Chemical Biology and the John A. Paulsen School of Engineering and Applied Sciences; Stanford University; and the Swiss Federal Institute of Technology in Zurich. The work was supported by the Simons Postdoctoral Fellowship, the U.S. Defense Advanced Research Projects Agency, the Bose Research Grant, and the National Institutes of Health.