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For Pi Day this year, we turned numerals seen around campus into an irrationally beautiful collage. Best wishes to everyone for a day filled with pi(e)!

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MIT chemists developed a battery cathode based on organic materials, which could reduce the EV industry’s reliance on scarce metals.

Anne Trafton | MIT News

Many electric vehicles are powered by batteries that contain cobalt — a metal that carries high financial, environmental, and social costs.

MIT researchers have now designed a battery material that could offer a more sustainable way to power electric cars. The new lithium-ion battery includes a cathode based on organic materials, instead of cobalt or nickel (another metal often used in lithium-ion batteries).

In a new study, the researchers showed that this material, which could be produced at much lower cost than cobalt-containing batteries, can conduct electricity at similar rates as cobalt batteries. The new battery also has comparable storage capacity and can be charged up faster than cobalt batteries, the researchers report.

“I think this material could have a big impact because it works really well,” says Mircea Dincă, the W.M. Keck Professor of Energy at MIT. “It is already competitive with incumbent technologies, and it can save a lot of the cost and pain and environmental issues related to mining the metals that currently go into batteries.”

Dincă is the senior author of the study, which appears today in the journal ACS Central Science. Tianyang Chen PhD ’23 and Harish Banda, a former MIT postdoc, are the lead authors of the paper. Other authors include Jiande Wang, an MIT postdoc; Julius Oppenheim, an MIT graduate student; and Alessandro Franceschi, a research fellow at the University of Bologna.

Alternatives to cobalt

Most electric cars are powered by lithium-ion batteries, a type of battery that is recharged when lithium ions flow from a positively charged electrode, called a cathode, to a negatively electrode, called an anode. In most lithium-ion batteries, the cathode contains cobalt, a metal that offers high stability and energy density.

However, cobalt has significant downsides. A scarce metal, its price can fluctuate dramatically, and much of the world’s cobalt deposits are located in politically unstable countries. Cobalt extraction creates hazardous working conditions and generates toxic waste that contaminates land, air, and water surrounding the mines.

“Cobalt batteries can store a lot of energy, and they have all of features that people care about in terms of performance, but they have the issue of not being widely available, and the cost fluctuates broadly with commodity prices. And, as you transition to a much higher proportion of electrified vehicles in the consumer market, it’s certainly going to get more expensive,” Dincă says.

Because of the many drawbacks to cobalt, a great deal of research has gone into trying to develop alternative battery materials. One such material is lithium-iron-phosphate (LFP), which some car manufacturers are beginning to use in electric vehicles. Although still practically useful, LFP has only about half the energy density of cobalt and nickel batteries.

Another appealing option are organic materials, but so far most of these materials have not been able to match the conductivity, storage capacity, and lifetime of cobalt-containing batteries. Because of their low conductivity, such materials typically need to be mixed with binders such as polymers, which help them maintain a conductive network. These binders, which make up at least 50 percent of the overall material, bring down the battery’s storage capacity.

About six years ago, Dincă’s lab began working on a project, funded by Lamborghini, to develop an organic battery that could be used to power electric cars. While working on porous materials that were partly organic and partly inorganic, Dincă and his students realized that a fully organic material they had made appeared that it might be a strong conductor.

This material consists of many layers of TAQ (bis-tetraaminobenzoquinone), an organic small molecule that contains three fused hexagonal rings. These layers can extend outward in every direction, forming a structure similar to graphite. Within the molecules are chemical groups called quinones, which are the electron reservoirs, and amines, which help the material to form strong hydrogen bonds.

Those hydrogen bonds make the material highly stable and also very insoluble. That insolubility is important because it prevents the material from dissolving into the battery electrolyte, as some organic battery materials do, thereby extending its lifetime.

“One of the main methods of degradation for organic materials is that they simply dissolve into the battery electrolyte and cross over to the other side of the battery, essentially creating a short circuit. If you make the material completely insoluble, that process doesn’t happen, so we can go to over 2,000 charge cycles with minimal degradation,” Dincă says.

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A new comic takes readers through a history of infectious disease discoveries. “A Paradigm Shift in Infectious Disease” follows MIT Associate Professor Lydia Bourouiba and artist Argha Manna, who are both protagonists and creators of the project.

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A low carbon abundance in planetary atmospheres, which the James Webb Space Telescope can detect, could be a signature of habitability.

Jennifer Chu | MIT News

Scientists at MIT, the University of Birmingham, and elsewhere say that astronomers’ best chance of finding liquid water, and even life on other planets, is to look for the absence, rather than the presence, of a chemical feature in their atmospheres.

The researchers propose that if a terrestrial planet has substantially less carbon dioxide in its atmosphere compared to other planets in the same system, it could be a sign of liquid water — and possibly life — on that planet’s surface.

What’s more, this new signature is within the sights of NASA’s James Webb Space Telescope (JWST). While scientists have proposed other signs of habitability, those features are challenging if not impossible to measure with current technologies. The team says this new signature, of relatively depleted carbon dioxide, is the only sign of habitability that is detectable now.

“The Holy Grail in exoplanet science is to look for habitable worlds, and the presence of life, but all the features that have been talked about so far have been beyond the reach of the newest observatories,” says Julien de Wit, assistant professor of planetary sciences at MIT. “Now we have a way to find out if there’s liquid water on another planet. And it’s something we can get to in the next few years.”

The team’s findings appear today in Nature Astronomy. De Wit co-led the study with Amaury Triaud of the University of Birmingham in the UK. Their MIT co-authors include Benjamin Rackham, Prajwal Niraula, Ana Glidden Oliver Jagoutz, Matej Peč, Janusz Petkowski, and Sara Seager, along with Frieder Klein at the Woods Hole Oceanographic Institution (WHOI), Martin Turbet of Ècole Polytechnique in France, and Franck Selsis of the Laboratoire d’astrophysique de Bordeaux.

Beyond a glimmer

Astronomers have so far detected more than 5,200 worlds beyond our solar system. With current telescopes, astronomers can directly measure a planet’s distance to its star and the time it takes it to complete an orbit. Those measurements can help scientists infer whether a planet is within a habitable zone. But there’s been no way to directly confirm whether a planet is indeed habitable, meaning that liquid water exists on its surface.

Across our own solar system, scientists can detect the presence of liquid oceans by observing “glints” — flashes of sunlight that reflect off liquid surfaces. These glints, or specular reflections, have been observed, for instance, on Saturn’s largest moon, Titan, which helped to confirm the moon’s large lakes.

Detecting a similar glimmer in far-off planets, however, is out of reach with current technologies. But de Wit and his colleagues realized there’s another habitable feature close to home that could be detectable in distant worlds.

“An idea came to us, by looking at what’s going on with the terrestrial planets in our own system,” Triaud says.

Venus, Earth, and Mars share similarities, in that all three are rocky and inhabit a relatively temperate region with respect to the sun. Earth is the only planet among the trio that currently hosts liquid water. And the team noted another obvious distinction: Earth has significantly less carbon dioxide in its atmosphere.

“We assume that these planets were created in a similar fashion, and if we see one planet with much less carbon now, it must have gone somewhere,” Triaud says. “The only process that could remove that much carbon from an atmosphere is a strong water cycle involving oceans of liquid water.”

Indeed, the Earth’s oceans have played a major and sustained role in absorbing carbon dioxide. Over hundreds of millions of years, the oceans have taken up a huge amount of carbon dioxide, nearly equal to the amount that persists in Venus’ atmosphere today. This planetary-scale effect has left Earth’s atmosphere significantly depleted of carbon dioxide  compared to its planetary neighbors.

“On Earth, much of the atmospheric carbon dioxide has been sequestered in seawater and solid rock over geological timescales, which has helped to regulate climate and habitability for billions of years,” says study co-author Frieder Klein.

The team reasoned that if a similar depletion of carbon dioxide were detected in a far-off planet, relative to its neighbors, this would be a reliable signal of liquid oceans and life on its surface.

“After reviewing extensively the literature of many fields from biology, to chemistry, and even carbon sequestration in the context of climate change, we believe that indeed if we detect carbon depletion, it has a good chance of being a strong sign of liquid water and/or life,” de Wit says.

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Floating into 2024 together. Happy new year, beavers!

In “Organs without Bodies,” Media Lab researcher Valdemar Danry and collaborator Cenk Güzeliş invited audiences to reflect on the implications of using generative AI and 3D printing to create objects without traditional human labor or design practices. The centerpiece of the installation was a dining table set with AI-generated objects—a teapot, teacups, plates, vase, and cutlery—envisioned by a custom built text-to-object machine learning model and materialized via 3D printing technologies. This project received support from the Council for the Arts at MIT.

Video: Jimmy Day/MIT Media Lab

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Study shows computational models trained to perform auditory tasks display an internal organization similar to that of the human auditory cortex.

Computational models that mimic the structure and function of the human auditory system could help researchers design better hearing aids, cochlear implants, and brain-machine interfaces. A new study from MIT has found that modern computational models derived from machine learning are moving closer to this goal.

In the largest study yet of deep neural networks that have been trained to perform auditory tasks, the MIT team showed that most of these models generate internal representations that share properties of representations seen in the human brain when people are listening to the same sounds.

The study also offers insight into how to best train this type of model: The researchers found that models trained on auditory input including background noise more closely mimic the activation patterns of the human auditory cortex.

“What sets this study apart is it is the most comprehensive comparison of these kinds of models to the auditory system so far. The study suggests that models that are derived from machine learning are a step in the right direction, and it gives us some clues as to what tends to make them better models of the brain,” says Josh McDermott, an associate professor of brain and cognitive sciences at MIT, a member of MIT’s McGovern Institute for Brain Research and Center for Brains, Minds, and Machines, and the senior author of the study.

MIT graduate student Greta Tuckute and Jenelle Feather PhD ’22 are the lead authors of the open-access paper, which appears today in PLOS Biology.

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Astronaut Woody Hoburg ’08 shares insights and advice with students in his first visit to campus since joining NASA.

The first question a student asked Warren “Woody” Hoburg ’08 during his visit to MIT's Department of Aeronautics and Astronautics (AeroAstro) this November was: “It seems like there’s no real way to know if being an astronaut is something you could really do. Are there any activities we can try out and see if astronaut-related things are something we might want to do?”

Hoburg’s response: There is no one path to space.

“If you look at all the classes of astronauts, there are all sorts of life paths that lead people to the astronaut corps. Do the things that are fun and exciting — work on things you’re excited to do just because it’s fulfilling in and of itself, not because of where it might lead,” he told a room full of Course 16 students.

Hoburg was the only faculty member among his peers in NASA’s Astronaut Class 22, for example. His own CV includes outdoor sports, computer science and robotics, EMT and search and rescue service, design optimization research, and flying airplanes.

In a two-day visit to the department that included a keynote lecture as well as fireside chats and Q&As with undergraduates and grad students, Hoburg shared his personal journey to becoming an astronaut, lessons and observations from his time aboard the International Space Station, and his excitement for what’s next in space exploration.

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Anushree Chaudhuri and Rupert Li will pursue graduate studies in the United Kingdom.

Julia Mongo | Office of Distinguished Fellowships

Anushree Chaudhuri and Rupert Li have won Marshall Scholarships, a prestigious British government-funded fellowship that offers exceptional American students the opportunity to pursue several years of graduate study in any field at any university in the United Kingdom. Up to 50 scholarships are awarded each year by the Marshall Aid Commemoration Commission.

The students were advised and supported by the distinguished fellowships team, led by Associate Dean Kim Benard in Career Advising and Professional Development. They also received mentorship from the Presidential Committee on Distinguished Fellowships, co-chaired by professors Will Broadhead and Nancy Kanwisher.

“The MIT students who applied for this year's Marshall Scholarship embody that combination of intellectual prowess, hard work, and civic-mindedness that characterizes the Institute at its best,” says Broadhead. “These students are truly amazing! The thoughtfulness and optimism they demonstrated throughout the months-long exercise in critical reflection and personal growth that the application process demands impressed and inspired us all. On behalf of the Distinguished Fellowships Committee, Nancy and I are thrilled to extend our warmest congratulations to Anushree and Rupert and our very best wishes as they take their richly deserved places in the Marshall Scholar community.”

Anushree Chaudhuri

Anushree Chaudhuri from San Diego, California, will graduate next spring with bachelor’s degrees in urban studies and planning and economics and a master's in city planning. As a Marshall Scholar, she plans to pursue an MPhil/PhD in environmental policy and development at the London School of Economics and Political Science. In the future, Chaudhuri hopes to work across the public and private sectors to drive structural changes that connect global environmental challenges to local community contexts. Since 2021, Chaudhuri has worked with Professor Larry Susskind in the Science Impact Collaborative to study local responses to large-scale renewable energy projects. This past summer, she traveled around California to document the experiences of rural and Indigenous communities most directly affected by energy transitions.

Chaudhuri has also worked with the U.S. Department of Energy, the World Wildlife Fund, and an environmental, social, and governance investing startup, as well as with several groups at MIT including the Office of Sustainability, Environmental Solutions Initiative, and the Climate and Sustainability Consortium. She represented MIT as an undergraduate delegate to the United Nations COP27. On campus, Chaudhuri co-leads the Student Sustainability Coalition, an umbrella organization for student sustainability groups. She has previously served as chair of Undergraduate Association Sustainability; a co-lead of the student campaign to revise MIT’s Fast Forward Climate Action Plan; judicial chair of Burton-Conner House; and as a representative on several campus committees, including the Corporation Joint Advisory Committee. She also loves to sing and write. In 2023, Chaudhuri was named a Udall Scholar and an MIT Burchard Scholar. By taking an interdisciplinary approach that combines law, planning, economics, participatory research, and data science, she is committed to a public service career addressing social and climate injustices.

Rupert Li

Hailing from Portland, Oregon, Rupert Li is a concurrent senior and master’s student at MIT. He will graduate in May 2024 with a BS in mathematics, a BS in computer science, economics, and data science, and a minor in business analytics. He will also be awarded an MEng in computer science, economics, and data science.

As a graduate student in the U.K., Li will pursue the MASt degree in pure mathematics at Cambridge University, followed by the MSc in mathematics and foundations of computer science at Oxford University. Li aspires to become a professor of mathematics.

Li has written 10 math research articles, primarily in combinatorics, but also including discrete geometry, probability, and harmonic analysis. Since his first-year fall, he has worked with Adjunct Professor Henry Cohn in the MIT Department of Mathematics and has authored two papers based on this work.

Li works on sphere-packing and coding theory, a famously challenging mathematical problem that has applications in error-correcting codes, which are ubiquitously used in the digital age to protect against data corruption. He currently also works with Professor Nike Sun in the MIT math department on probability theory and Professor Jim Propp of the University of Massachusetts at Lowell on enumerative combinatorics and statistical mechanics.

A robot developed by MIT students Ben Katz and Jared Di Carlo can solve a Rubik’s Cube in a record-breaking 0.38 seconds.

Professor Benedetto Marelli develops silk-based technologies with uses “from lab to fork,” including helping crops grow and preserving perishable foods.

Michaela Jarvis | MIT News correspondent

Growing up in Milan, Benedetto Marelli liked figuring out how things worked. He repaired broken devices simply to have the opportunity to take them apart and put them together again. Also, from a young age, he had a strong desire to make a positive impact on the world. Enrolling at the Polytechnic University of Milan, he chose to study engineering.

“Engineering seemed like the right fit to fulfill my passions at the intersection of discovering how the world works, together with understanding the rules of nature and harnessing this knowledge to create something new that could positively impact our society,” says Marelli, MIT’s Paul M. Cook Career Development Associate Professor of Civil and Environmental Engineering.

Marelli decided to focus on biomedical engineering, which at the time was the closest thing available to biological engineering. “I liked the idea of pursuing studies that provided me a background to engineer life,” in order to improve human health and agriculture, he says.

Marelli went on to earn a PhD in materials science and engineering at McGill University and then worked in Tufts University’s biomaterials Silklab as a postdoc. After his postdoc, Marelli was drawn to MIT’s Department of Civil and Environmental in large part because of the work of Markus Buehler, MIT’s McAfee Professor of Engineering, who studies how to design new materials by understanding the architecture of natural ones.

“This resonated with my training and idea of using nature’s building blocks to build a more sustainable society,” Marelli says. "It was a big leap forward for me to go from biomedical engineering to civil and environmental engineering. It meant completely changing my community, understanding what I could teach and how to mentor students in a new engineering branch. As Markus is working with silk to study how to engineer better materials, this made me see a clear connection with what I was doing and what I could be doing. I consider him one of my mentors here at MIT and was fortunate to end up collaborating with him."

Marelli’s research is aimed at mitigating several pressing global problems, he says.

“Boosting food production to provide food security to an ever-increasing population, soil restoration, decreasing the environmental impact of fertilizers, and addressing stressors coming from climate change are societal challenges that need the development of rapidly scalable and deployable technologies,” he says.

Marelli and his fellow researchers have developed coatings derived from natural silk that extend the shelf life of food, deliver biofertilizers to seeds planted in salty, unproductive soils, and allow seeds to establish healthier plants and increase crop yield in drought-stricken lands. The technologies have performed well in field tests being conducted in Morocco in collaboration with the Mohammed VI Polytechnic University in Ben Guerir, according to Marelli, and offer much potential.

“I believe that with this technology, together with the common efforts shared by the MIT PIs participating in the Climate Grand Challenge on Revolutionizing Agriculture, we have a  real opportunity to positively impact planetary health and find new solutions that work in both rural settings and highly modernized agricultural fields,” says Marelli, who recently earned tenure.

As a researcher and entrepreneur with about 20 patents to his name and awards including a National Science Foundation CAREER award, the Presidential Early Career Award for Scientists and Engineers award, and the Ole Madsen Mentoring Award, Marelli says that in general his insights into structural proteins — and how to use that understanding to manufacture advanced materials at multiple scales — are among his proudest achievements.

More specifically, Marelli cites one of his breakthroughs involving a strawberry. Having dipped the berry in an odorless, tasteless edible silk suspension as part of a cooking contest held in his postdoctoral lab, he accidentally left it on his bench, only to find a week or so later that it had been well-preserved.

“The coating of the strawberry to increase its shelf life is difficult to beat when it comes to inspiring people that natural polymers can serve as technical materials that can positively impact our society” by lessening food waste and the need for energy-intensive refrigerated shipping, Marelli says.

When Marelli won the BioInnovation Institute and Science Prize for Innovation in 2022, he told the journal Science that he thinks students should be encouraged to choose an entrepreneurial path. He acknowledged the steepness of the learning curve of being an entrepreneur but also pointed out how the impact of research can be exponentially increased.

He expanded on this idea more recently.

“I believe an increasing number of academics and graduate students should try to get their hands ‘dirty’ with entrepreneurial efforts. We live in a time where academics are called to have a tangible impact on our society, and translating what we study in our labs is clearly a good way to employ our students and enhance the global effort to develop new technology that can make our society more sustainable and equitable,” Marelli says.

Referring to a spinoff company, Mori, that grew out of the coated strawberry discovery and that develops silk-based products to preserve a wide range of perishable foods, Marelli says he finds it very satisfying to know that Mori has a product on the market that came out of his research efforts — and that 80 people are working to translate the discovery from “lab to fork.”

“Knowing that the technology can move the needle in crises such as food waste and food-related environmental impact is the highest reward of all,” he says.

Marelli says he tells students who are seeking solutions to extremely complicated problems to come up with one solution, “however crazy it might be,” and then do an extensive literature review to see what other researchers have done and whether “there is any hint that points toward developing their solution.”

“Once we understand the feasibility, I typically work with them to simplify it as much as we can, and then to break down the problem in small parts that are addressable in series and/or in parallel,” Marelli says.

That process of discovery is ongoing. Asked which of his technologies will have the greatest impact on the world, Marelli says, “I’d like to think it’s the ones that still need to be discovered.”

More stable clocks could measure quantum phenomena, including the presence of dark matter.

Jennifer Chu | MIT News

The practice of keeping time hinges on stable oscillations. In a grandfather clock, the length of a second is marked by a single swing of the pendulum. In a digital watch, the vibrations of a quartz crystal mark much smaller fractions of time. And in atomic clocks, the world’s state-of-the-art timekeepers, the oscillations of a laser beam stimulate atoms to vibrate at 9.2 billion times per second. These smallest, most stable divisions of time set the timing for today’s satellite communications, GPS systems, and financial markets.

A clock’s stability depends on the noise in its environment. A slight wind can throw a pendulum’s swing out of sync. And heat can disrupt the oscillations of atoms in an atomic clock. Eliminating such environmental effects can improve a clock’s precision. But only by so much.

A new MIT study finds that even if all noise from the outside world is eliminated, the stability of clocks, laser beams, and other oscillators would still be vulnerable to quantum mechanical effects. The precision of oscillators would ultimately be limited by quantum noise.

But in theory, there’s a way to push past this quantum limit. In their study, the researchers also show that by manipulating, or “squeezing,” the states that contribute to quantum noise, the stability of an oscillator could be improved, even past its quantum limit.

“What we’ve shown is, there’s actually a limit to how stable oscillators like lasers and clocks can be, that’s set not just by their environment, but by the fact that quantum mechanics forces them to shake around a little bit,” says Vivishek Sudhir, assistant professor of mechanical engineering at MIT. “Then, we’ve shown that there are ways you can even get around this quantum mechanical shaking. But you have to be more clever than just isolating the thing from its environment. You have to play with the quantum states themselves.”

The team is working on an experimental test of their theory. If they can demonstrate that they can manipulate the quantum states in an oscillating system, the researchers envision that clocks, lasers, and other oscillators could be tuned to super-quantum precision. These systems could then be used to track infinitesimally small differences in time, such as the fluctuations of a single qubit in a quantum computer or the presence of a dark matter particle flitting between detectors.

“We plan to demonstrate several instances of lasers with quantum-enhanced timekeeping ability over the next several years,” says Hudson Loughlin, a graduate student in MIT’s Department of Physics. “We hope that our recent theoretical developments and upcoming experiments will advance our fundamental ability to keep time accurately, and enable new revolutionary technologies.”

Loughlin and Sudhir detail their work in an open-access paper published in the journal Nature Communications.

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Zach Winn | MIT News

Students fill the glass-walled room and spill out into the common area. They gather around tables and desks cluttered with board games and game pieces. Along the far wall, large screens show students exploring the latest virtual reality experience alongside classmates reliving their favorite retro videogames.

Welcome to an open house of the MIT Game Lab, where play and experimentation are joined by serious inquiry about the gaming industry and its role in society.

In addition to its rollicking open houses, which take place at least once a semester, the Game Lab hosts public events, organizes research projects, and teaches courses through MIT Comparative Media Studies/Writing (CMS/W).

The Game Lab’s work is designed to help students think critically about the games they’ve often been playing for years without considering the values they might project, and to prepare them to engage in thoughtful design practices themselves.

“Students come to the Game Lab because it sounds like fun, which is great, but they realize through our research that there’s also something really serious at work in games,” Game Lab Director and Professor T.L. Taylor says. “I think students often have this moment where they realize this thing they’ve been enjoying actually has a lot of stakes in it; these are things that really matter.”

The Game Lab analyzes the gaming industry and its impact, explores new technologies and formats, and creates games that tackle important issues. Many new games are tied to larger research projects.

“There’s a desire from our students to express themselves through games, whether that’s through making educational games or games with specific messages or lessons,” says Game Lab research scientist and lecturer Mikael Jakobsson. “Games are a big part of most people’s lives, so there’s a thirst among our students for not only learning how to make games, but also studying games as social and cultural artefacts.”

Through that research, students come to appreciate the impact of games on the world.

“Game are hugely important in society and culture,” Taylor says. “We’re really trying to always think critically and productively about what we do with this powerful form of media and entertainment, and to think about games as a place in which imagination and stories about the world can be worked over and thought about.”

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Video: Melanie Gonick/MIT

A team of engineers has developed a new 3D inkjet printing system that utilizes computer vision for contact-free 3D printing, letting engineers print with high-performance materials they couldn’t use before.

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Metamaterials are products of engineering wizardry. They are made from everyday polymers, ceramics, and metals. And when constructed precisely at the microscale, in intricate architectures, these ordinary materials can take on extraordinary properties.

With the help of computer simulations, engineers can play with any combination of microstructures to see how certain materials can transform, for instance, into sound-focusing acoustic lenses or lightweight, bulletproof films.

But simulations can only take a design so far. To know for sure whether a metamaterial will stand up to expectation, physically testing them is a must. But there’s been no reliable way to push and pull on metamaterials at the microscale, and to know how they will respond, without contacting and physically damaging the structures in the process.

Now, a new laser-based technique offers a safe and fast solution that could speed up the discovery of promising metamaterials for real-world applications.

The technique, developed by MIT engineers, probes metamaterials with a system of two lasers — one to quickly zap a structure and the other to measure the ways in which it vibrates in response, much like striking a bell with a mallet and recording its reverb. In contrast to a mallet, the lasers make no physical contact. Yet they can produce vibrations throughout a metamaterial’s tiny beams and struts, as if the structure were being physically struck, stretched, or sheared.

The engineers can then use the resulting vibrations to calculate various dynamic properties of the material, such as how it would respond to impacts and how it would absorb or scatter sound. With an ultrafast laser pulse, they can excite and measure hundreds of miniature structures within minutes. The new technique offers a safe, reliable, and high-throughput way to dynamically characterize microscale metamaterials, for the first time.

“We need to find quicker ways of testing, optimizing, and tweaking these materials,” says Carlos Portela, the Brit and Alex d’Arbeloff Career Development Professor in Mechanical Engineering at MIT. “With this approach, we can accelerate the discovery of optimal materials, depending on the properties you want.”

Portela and his colleagues detail their new system, which they’ve named LIRAS (for laser-induced resonant acoustic spectroscopy) in a paper appearing today in Nature. His MIT co-authors include first author Yun Kai, Somayajulu Dhulipala, Rachel Sun, Jet Lem, and Thomas Pezeril, along with Washington DeLima at the U.S. Department of Energy’s Kansas City National Security Campus.

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High schooler Dustin Liang estimated his blood cell counts by applying knowledge from an MITx course and talking to doctors.

Sara Feijo | MIT Open Learning

When Dustin Liang was diagnosed with T-cell acute lymphoblastic leukemia in June, the cancer consumed his life. But despite a monthlong hospital stay, aggressive chemotherapy treatments, and ongoing headaches, fatigue, loss of appetite, and nausea, the 17-year-old high school senior enrolled in MITx’s class 18.01.1x (Calculus 1A: Differentiation).

MITx, part of MIT Open Learning, offers hundreds of high-quality massive open online courses adapted from the MIT classroom for learners worldwide. The Calculus 1A: Differentiation course was designed and created by the Department of Mathematics and offered through the MITx program. Liang took the free course this summer in between treatment sessions and medical tests so that he could meet the four-year math requirement to graduate from a Massachusetts high school — an arrangement he made with his school. 

In class, Liang learned how to differentiate functions and how to make linear and quadratic approximations. He then applied this knowledge to estimate his blood cell counts. “I was in a hospital bed when I saw the doctor draw a graph of my neutrophils on a whiteboard, and I thought you could apply a quadratic approximation to it to estimate my blood cell counts at a certain time in the future,” Liang recalls. “I talked to the doctors about it, and they said it was a good idea but that they currently didn’t have the technology to do that.”

In Calculus 1A, Liang was learning how to predict the near future value of a function using linear or quadratic approximation methods. After seeing a doctor’s chart of his neutrophils, Liang hypothesized that he could use quadratic approximation to predict his neutrophil count. 

“Given a series of points of the blood cell counts, a function can be modeled,” Liang explains. “So, predicting a future point not far away is mathematically feasible.”

Determined to test his idea, Liang called his mentor, Jiawen Sun, who works in a London security exchange firm as a trading analyst simulating and modeling stock market behavior. Sun helped Liang create a graph to estimate Liang’s neutrophil count at a certain time. When Liang compared the graph to his blood test results, he found that the math worked.

“I was able to predict the blood cell counts. It was a little off, but close enough,” Liang says. “There are some challenges in simulating the function of blood cells. However, the human blood cell counts turned out to be converging easier than the stock market to simulate.”

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