New center will push frontiers of sensing technology

In anticipation of the official opening of the new MIT.nano building — which will house some of the world’s leading facilities supporting research in nanoscience and nanotechnology — MIT last week officially launched a new “center of excellence” called SENSE.nano, which is dedicated to pushing the frontiers of research in sensing technologies.

Like the new building, which is slated to open a year from now, SENSE.nano is an endeavor that cuts across the divisions of departments, labs, and schools, to encompass research in areas including chemistry, physics, materials science, electronics, computer science, biology, mechanical engineering, and more. Faculty members from many of these areas spoke about their research during a daylong conference on May 25 that marked the official launch of the new center.

Introducing the event, MIT President L. Rafael Reif said that “[MIT.nano] will create opportunities for research and collaboration for more than half our current faculty, and 67 percent of those recently tenured. In fact, we expect that it will serve — and serve to inspire – more than 2,000 people across our campus, from all five MIT schools, and many more from beyond our walls.”

Explaining the impetus for creating this new center, Reif said that MIT is “famous for making — because we have a community of makers — a concentration of brilliant people who are excited to share their experience and their ideas, to teach you to use their tools and to learn what you know, too. On a much bigger scale, this is the same magic we hope for in creating SENSE.nano. As MIT.nano’s first ‘center of excellence,’ SENSE.nano will bring together a wide array of researchers, inventors, and entrepreneurs fascinated by the potential of sensors and sensing systems to transform our world.”

The development of new kinds of connected, inexpensive, and widespread sensing devices, harnessing the power of nanoscale imaging and manufacturing systems, could impact many of the world’s most pressing problems, said Vincent Roche, president of Analog Devices, who gave the opening keynote talk. Such new technology “has the potential to solve problems that have plagued humanity for millennia, including food and water security, health care, and environmental degradation.”

The 200,000-square-foot facility, in addition to more than doubling the amount of clean-room imaging and fabrication space available to MIT researchers, also contains “one of the quietest spaces on the eastern seaboard,” said Brian Anthony, co-leader of the new center of excellence and a principal researcher in the mechanical engineering department, referring to an exceptionally vibration-free environment created on the new building’s basement level, where the most sensitive of instruments, that require a perfectly stable base, will be housed.

To show by example what some of that cross-disciplinary work will look like, several faculty members described the research they are doing now and explained how its scope and capabilities will be greatly enhanced by the new imaging and fabrication tools that will become available when MIT.nano officially opens for research.

Tim Swager, the John D. MacArthur Professor of Chemistry, described ongoing work that he and his students have been doing on developing tiny, low-cost sensors that can be incorporated in the packaging of fruits and vegetables. The sensors could detect the buildup of gases that could lead to premature ripening or rotting, as a way to reduce the amount of food wasted during transportation and storage. Polina Anikeeva, the Class of 1942 Career Development Associate Professor in Materials Science and Engineering, talked about developing flexible, stretchable fibers for implantation in brain and spinal cord tissues, which could ultimately lead to ways of restoring motion to those with spinal cord injuries.

Others described large-area sensing systems that could incorporate computation and logic so that only the most relevant data would need to be transmitted, helping to curb a data overload; and sensors built from nanotubes that could be bent, twisted, or stretched while still gathering data. Still others described ways of integrating electronics with photonic devices, which use light instead of electrons to carry and manipulate data. Also presented was work on using fluorescing quantum-dot particles to provide imaging of living tissues without the need for incisions, and building sensors that can continuously monitor buildings, bridges, and other structures to detect signs of likely failure long before disaster strikes.

“The future will be measured in nanometers,” said MIT Professor Vladimir Bulovic, in a panel discussion at the end of the conference, moderated by Tom Ashbrook, host of NPR’s “On Point.” Bulovic, who is the faculty lead for the MIT.nano building and the Fariborz Maseeh Chair in Emerging Technology, added, “We are right now at the renaissance age of nano.” He noted that devices all around us — and in our pockets — are constantly sensing, recording, and sometimes transmitting data about our surroundings.

“We can access data on how the world around us really functions, and with that data, we can take the next step of influencing the environment” to improve our health, protect our natural environment, and monitor our buildings, structures, and devices to make sure they are working as they should, he said. “The opportunity is vast.”

In his introduction, Reif also hailed the potential of what’s sometimes called “ubiquitous sensing”: “Tomorrow’s optical, mechanical, electrical, chemical, and biological sensors, alone and networked together, offer a huge range of new possibilities in terms of understanding and controlling the world around us. Sensors will change how we protect our soldiers and keep our bridges safe. How we monitor the polar ice caps, and monitor how children learn. Sensors will change how we keep our water clean, our patients healthy, and our energy supply secure. … In short, sensors and sensing systems will be the source of new products, new capabilities — and whole new industries. And we should not be surprised if some of them are deeply disruptive.”

Disruption, of course, can be a two-edged sword. So, Reif said, one of the challenges facing those who innovate in this field, “as technology races to the future, is how to help society navigate its unintended impacts. … If we can make this a first concern, and not an afterthought, I have no doubt that this community will continue to be a major force in making a better world.”

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Project Apophis

Alissa Michelle Earle is rehearsing in front of her class. She stands before a presentation slide, and reads: “Mission Motivation: Apophis is coming!”  

“It’s not going to impact Earth but it’s going to come very close to us,” explains Earle, a graduate student in the Department of Earth, Atmospheric and Planetary Sciences.

Apophis is an asteroid the size of an aircraft carrier that will come within 5.5 Earth radii in 2029. As part of 16.83 (Space Systems Engineering), Earle is one of 20 students tasked with designing a space mission to measure the asteroid's internal structure and potential long-term impact hazard.

Professor of planetary sciences Richard Binzel is leading 16.83 with David Miller, the Jerome C. Hunsaker Professor of Aeronautics and Astronautics, who recently returned to MIT after serving as chief technologist for NASA. Inspired by Apophis, the professors teamed up to issue MIT students a challenge: Build a major science robotics mission that marries planetary defense with scientific learning.

The ingenuity of their MIT students soon blew Binzel and Miller away. Early on, the pair advised NASA colleagues of the project and invited their participation in a series of design reviews. As Miller notes, “Both Rick and I have a rolodex at NASA, and as the class progressed, the audience for our reviews grew bigger and bigger.”

Today Binzel and Miller are helping students get ready for a major final review, which will be attended by NASA Headquarters officials and engineers from NASA’s Jet Propulsion Laboratory (JPL). During the trial run, the students are well-prepared but nervous — fidgeting, speed talking, making edits. As Earle speaks, a woman in the audience of students and visiting faculty shouts: “There are a lot of scientific terms you’re using here that we’ve never heard before!”

“You don’t need to get into the specifics right at the beginning,” coaches Binzel, who is one of the world’s top scientists in the study of asteroids and Pluto.

When MIT senior Diego Mundo, an aeronautical and astronautical engineering major, dives into spacecraft instrument design, Binzel interrupts: “Are you sure that will work?”

“I am sure,” says Mundo, who is dressed in a black t-shirt with colored bracelets covering his arms and hair flying out of a ponytail in all directions. But his expression is that of a stern academic as he allows that: “I may not have used the correct words.”

“That’s what today is for,” says Binzel. “You’re getting the feedback to make sure that everything is clear. Let’s go again.”

Space mission

The students want to get their performance and the science just right, since asteroid flyby events on the order of Apophis happen only once about every 1,000 years.

The students' general mission objectives include characterizing the asteroid’s shape, size, density, surface topography, surface composition, rotation rate, and spin state. A NASA spacecraft would have to be launched in August of 2026 to reach the observation position in time. The objective is to get the craft close enough to Apophis to conduct measurements before, during, and after the 2029 event.

Surprisingly, the student-designed mission is the first significant attempt to take on Apophis, which is 350 meters across with a mass of 20 million metric tons. At NASA, Miller says people tend to split into a couple of camps: those in space flight (or the “space cadets,” like him) and the scientists (like Binzel, whom he refers to as an “asteroid hunter extraordinaire”).

Exploration of the hazards posed by asteroids does not quite fit into either camp, Miller says, “so that kind of falls between the cracks at NASA.”

Project Apophis, as Binzel likes to say, is a “kick-starter” — designed to encourage further studies by international space agencies. And for good reason, Miller adds.

“There have been plenty of missions to comets and asteroids, so why is this unique?” he explains. “Apophis is coming so close that Earth’s gravity is going to tug and redirect its path. The Earth is going to give it a big thunk.”

The outcome of that planetary torque will teach scientists more about the construction of asteroids, which were some of the early building blocks of our own solar system. New information could lead to a deeper understanding of the formation of our solar system and the more than 4,000 known planets around other stars. More pragmatically, what we learn from the Apophis encounter could strengthen our knowledge of how to mount a planetary defense in the event an asteroid was ever discovered and verified to be on an impact course.

The big day

On the big day, the room is quiet, and the students are dressed up. Even Mundo appears in a button-up (albeit wrinkled) shirt, with his hair in a tidy bun.

Among the listening experts are NASA Planetary Defense Officer Lindley Johnson, who directs a program for detecting and tracking near-Earth objects; Paul Chodas, who heads the Center for Near-Earth Objects at JPL; and Farah Alibay PhD '14 a JPL systems engineer.

The practice sessions pay off. The students hit a rhythm, and take tough questions as smaller subteams, based on areas of expertise.

“How well do you know the orbit of Apophis after the flyby event?” “Do you have the equipment to change your operation plans if there’s a change in the asteroid?” “Do you know what the rotation vector of the asteroid is?"

The teams don't necessarily have all the answers: “Okay, we can look into that.” “We’ll do the analysis.” “Thanks for the input.”

But the experts are impressed. “It’s a really good effort,” NASA's Johnson says in an encouraging tone. “It’s almost ready for a NASA proposal.”

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Understanding anthropogenic effects on space weather

Effects of human behavior are not limited to Earth's climate or atmosphere; they are also seen in the natural space weather surrounding our planet. "Space weather" in this context includes conditions in the space surrounding Earth, including the magnetosphere, ionosphere, and thermosphere.

A recent survey by a team of scientists including Phil Erickson, assistant director of MIT Haystack Observatory, has resulted in an article in the journal Space Science Reviews. The study provides a comprehensive review of anthropogenic, or human-caused, space weather impacts, including some recent findings using NASA's Van Allen Probes twin spacecraft.

As space scientist James Van Allen discovered in the 1950s and 1960s, two radiation belts surround Earth with a slot between them. The inner edge of the outer Van Allen radiation belt is particularly interesting, as it is composed of high-energy "killer" electrons that have the potential to permanently damage spacecraft. Tracking the inner edge of the radiation belt is important for GPS navigation, communication, and other satellite-based systems to help protect them from this naturally occurring radiation. 

Until recently, it was thought that the inner edge of the outer belt was under nearly all conditions located at the plasmapause, the outer boundary of cold, dense plasma surrounding Earth that is produced daily by the sun's extreme ultraviolet rays. During geomagnetic storms, extra energy from solar flares and coronal mass ejections interact with and compress the plasmasphere. Scientists originally thought that under these conditions, the inner edge of the outer Van Allen belt would contract with the compression of the plasmasphere and move closer to Earth.

Research using the Van Allen Probes has discovered instead that during particularly intense geomagnetic storms, the inner edge of the outer belt does not follow suit but instead keeps its distance from the Earth, holding off the inner extent of "killer electrons" possessing damage potential. This inner limit to high-energy electrons occurs at the edge of strong human-origin radio transmissions created for a very different purpose.

Strong very low frequency (VLF) radio waves have been used for nearly a century to communicate with submarines, as they penetrate seawater well. But in addition to traveling through the ocean, the VLF waves also propagate upward along magnetic field lines and form a "bubble" of VLF transmissions, reaching to about the same spot that the ultra-relativistic electrons seem to stop during superstorms. The communications signals can interact with and remove some of these high-energy particles through loss to our atmosphere. This new understanding implies that human-origin systems can have an unexpected effect on high-energy space weather around our planet during these unusual, intense storms in space.

The Space Science Reviews survey also explores a more direct effect caused by humans on the near-Earth space environment. High-altitude nuclear detonation tests during the Cold War also affected the near-Earth environment by creating long-lasting artificial radiation belts that disrupted power grids and satellite transmissions. Such tests are now banned: In particular, the 1963 Partial Test Ban Treaty — signed by all nuclear powers at the time — specifically prohibits nuclear weapons testing in the atmosphere. However, a large body of information on the effects of these atmospheric tests exists, and the article examines these historical nuclear explosions to further study of anthropogenic effects on space weather. 

Understanding human-origin space weather under these extreme conditions allows us to greatly enhance our knowledge of natural effects and allows essential engineering and scientific work aimed at protecting the planet's ground-based and satellite technology. “Nuclear atmospheric tests were a human-generated and extreme example of some of the space weather effects frequently caused by the sun,” says Erickson. “If we understand what happened in the somewhat controlled and definitely extreme conditions caused by one of these man-made events, and combine it with studies into longer term effects such as the VLF communications 'bubble,' we can more readily advance our knowledge and prediction of natural variations in the near-space environment.”

The work highlights the importance of continuing research into space weather — both naturally occurring effects and those influenced by human behavior — as an essential part of society's advance toward a more complex, spacefaring society.

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LIDS Smart Urban Infrastructures Workshop highlights emerging research

Data can reveal valuable insights about the ways humans interact with their urban surroundings, helping to determine the types of services and systems they need and how those services and systems should work. Transportation, the electric power grid, and other services people rely upon can become more automated and more responsive — and ultimately smarter — through data science approaches.

Those ideas were at the center of the Smart Urban Infrastructures Workshop, which was held May 11-12 at the Media Lab. The event was hosted by the Laboratory for Information and Decisions Systems (LIDS), which is both the longest-running research laboratory at MIT and the major research lab of the MIT Institute for Data, Systems, and Society (IDSS). 

“Thanks to advances in technology, we see more and more smart services,” said Asuman Ozdaglar, the Joseph F. and Nancy P. Keithley Professor in Electrical Engineering and head of the Department of Electrical Engineering and Computer Science. “These smart services take many forms and include increasingly more platforms for sharing resources.”

The conference was organized around six central themes related to smart services: security and privacy; smart cities and communities; communications and the internet of things; transportation services and platforms; autonomous transportation; and smart grid and energy services. The first day included a student poster session, while the second day featured a keynote talk from GE Digital Vice President Peter Marx, who also drew from some of his past experiences in the public sector as chief technology officer for the City of Los Angeles.

Speakers on the Security and Privacy in Smart Services panel shared a variety of perspectives on current privacy challenges. Daniel Weitzner, founding director of the MIT Internet Policy Research Initiative and principal research scientist at the Computer Science and Artificial Intelligence Laboratory (CSAIL), discussed the need to understand the significance and meaning of privacy in people’s lives in order to create effective policies. He explored the complexity that emerges when people try to define exactly what privacy is in terms of how people perceive and value it.

“It’s tempting to have a single, formal definition of ‘privacy,” he said, “but we can’t do that. Privacy means different things to different people.”

Lalitha Sankar, assistant professor in the School of Electrical, Computer and Energy Engineering at Arizona State University, addressed privacy and security in the context of power systems — including looking at the importance of cybersecurity in maintaining the operations of smart cities. She cited the example of a major cyber attack that disabled a third of the Ukrainian power grid to illustrate a case in which “the control was bypassed from the human in the loop,” and where the cyber system itself was unable to identify the problem.

During the panel session on Smart Cities and Communities, Mark Gorenberg, the founder and managing director of Zetta Partners, talked about strategies for making communities more energy-efficient and more connected by using data related to local preferences and needs. Fellow panelist Glenn Ricart of US Ignite emphasized the importance of “civic partnerships,” including work with volunteers and universities.

Amy Glasmeier, professor in the MIT Department of Urban Studies and Planning, focused on the ongoing challenge of providing more access to smart services for wider segments of the population.

“How do we change and broaden the demographics [of people using smart systems]?” Glasmeier asked. In designing smart systems, she said the key question needs to be: “What is the problem we are trying to solve, and for whom?”

In the panel on Communications and the Internet of Things in Smart Cities, Veniam CEO and founder João Barros discussed some communications applications that can improve cities, such as having vehicles share software updates.

“Many applications allow you to reduce traffic if vehicles can communicate with each other,” he said.

Iyad Rahwan, a professor at the Media Lab and IDSS affiliate faculty member, presented some of his research on the complex ethical dilemmas of autonomous vehicles. Human drivers make quick, intuitive, and often high-stakes decisions to assess relative risk and act accordingly. Although efforts toward building these capabilities in cars are well underway, designing such complex systems presents great challenges, he said.

The Smart Grid and Energy Services panel also highlighted the human component of smart systems. Marija Ilic, an IDSS visiting professor, talked about the need to think about power grids as “data-enabled, socio-ecological systems.” Ilic and other panelists discussed the importance of making it easy for consumers to participate in decisions about energy usage — particularly by using data to identify certain tasks and decisions and then automate them.

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Making prosthetic limbs feel more natural

A new surgical technique devised by MIT researchers could allow prosthetic limbs to feel much more like natural limbs. Through coordination of the patient’s prosthetic limb, existing nerves, and muscle grafts, amputees would be able to sense where their limbs are in space and to feel how much force is being applied to them.

This type of system could help to reduce the rejection rate of prosthetic limbs, which is around 20 percent.

“We’re talking about a dramatic improvement in patient care,” says Hugh Herr, a professor of media arts and sciences and the senior author of the study. “Right now there’s no robust neural method for a person with limb amputation to feel proprioceptive positions and forces applied to the prosthesis. Imagine how that would completely hinder one’s ability to move, to successfully balance, or to manipulate objects.”

In the new study, which appears in Science Robotics on May 31, the researchers demonstrated in rats that their technique generates muscle-tendon sensory feedback to the nervous system, which should be able to convey information about a prosthetic limb’s placement and the forces applied to it. They now plan to begin implementing this approach in human amputees, including Herr, whose legs were amputated below the knee when he was 17.

Shriya Srinivasan, a graduate student in the Harvard-MIT Program in Health Sciences and Technology (HST), is the paper’s lead author. Other authors are Media Lab visiting scientist Matthew Carty, MIT undergraduate Peter Calvaresi, HST graduate students Tyler Clites and Benjamin Maimon, Media Lab graduate student Cameron Taylor, and recent PhD recipient Anthony Zorzos.

Better feedback

During a conventional limb amputation, muscles are severed in a way that cuts off a key relationship that normally helps people control their limbs and sense where they are in space. Most muscles that control limb movement occur in pairs known as agonist-antagonist pairs, such that one muscle stretches when the other contracts. For example, when you bend your elbow, the biceps muscle contracts, causing the triceps to stretch, and that triceps stretch sends sensory information related to position, velocity, and force back to the brain. The agonist-antagonist muscle relationship is also what allows people to independently control  position and stiffness at their limb joints.

Without these intact muscle pairs, persons with limb amputation have no way of sensing where their artificial limbs are, nor can they sense the forces applied to those limbs.

“They have to visually follow their hands or their limbs, because there isn’t any feedback from the device or residual limb that tells their brain where their prosthetic limbs are in space,” Srinivasan says.

The MIT team set out to recreate these agonist-antagonist muscle relationships. In many amputees, the nerves that send signals to the amputated limb remain intact. The researchers decided to take advantage of those nerves by connecting them to muscle pairs grafted from another part of the body into the amputation site.

These grafts, which would be about 4 centimeters by 1.5 centimeters in humans, consist of a pair of muscles that work together just like natural muscles. When the brain sends signals instructing a limb to move, one of the grafted muscles will contract, and its agonist will extend. The agonist muscle then sends feedback to the brain about how much the muscle moved and the forces applied to it.

In the Science Robotics paper, the researchers tested the muscle grafts in rats and found that when the rats contracted one muscle of the pair, the other muscle would move in the opposite way and send sensory information back to the brain.

Control system

In other work, the researchers have developed the components of a control system that will translate the nerve signals into instructions for moving the prosthetic limb. When the brain sends nerve impulses to the regenerated muscles, those signals will also be received by a microprocessor that controls the movement of the artificial limb.

Neural stimulations will cause the agonist muscle to contract and the antagonist muscle to stretch. The stretched muscle will then provide neural feedback to allow the patient to feel where his or her limb is in space. The researchers expect that the brain will be able to rapidly learn how much control it has to exert to make an artificial limb move in the desired way.

“Using this framework, the patient will not have to think about how to control their artificial limb. When a patient imagines moving their phantom limb, signals will be sent through nerves to the surgically constructed muscle pairs. Implanted muscle electrodes will then sense these signals for the control of synthetic motors in the external prosthesis,” Herr says. “We think that because the brain is so good at remapping and it’s so plastic, it will quickly adapt to knowing how much it has to contract each muscle graft for natural prosthetic control.”

This type of feedback system should also allow people with a prosthetic arm, for example, to feel a torque applied to the prosthesis. “If you were to give a prosthetic-arm user a barbell to hold, they would actually feel the torque on the prosthetic wrist joint,” Herr says.

The researchers anticipate that this strategy could work for nearly any amputee, including people whose amputations were performed many years ago.

“For almost any amputation scenario, as long as we have a little bit of the healthy nerve left, we can take that and put it into regenerative muscle grafts. We can harvest these muscle grafts from almost anywhere in the body, making this applicable to a large number of cases ranging from trauma to chronic pain,” Srinivasan says.

Rickard Branemark, an associate professor of orthopedic surgery at the University of California at San Francisco School of Medicine, describes the new MIT approach as “a brilliant idea.”

“It’s solving one of the major challenges when it comes to control of artificial limbs, which is sensing where the limb is in space,” says Branemark, who was not involved in the study. “If it can be done in humans, the risks involved are fairly limited and the potential benefit could be really huge.”

The research was funded by the MIT Media Lab Consortia.

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Wearable system helps visually impaired users navigate

Computer scientists have been working for decades on automatic navigation systems to aid the visually impaired, but it’s been difficult to come up with anything as reliable and easy to use as the white cane, the type of metal-tipped cane that visually impaired people frequently use to identify clear walking paths.

White canes have a few drawbacks, however. One is that the obstacles they come in contact with are sometimes other people. Another is that they can’t identify certain types of objects, such as tables or chairs, or determine whether a chair is already occupied.

Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have developed a new system that uses a 3-D camera, a belt with separately controllable vibrational motors distributed around it, and an electronically reconfigurable Braille interface to give visually impaired users more information about their environments.

The system could be used in conjunction with or as an alternative to a cane. In a paper they’re presenting this week at the International Conference on Robotics and Automation, the researchers describe the system and a series of usability studies they conducted with visually impaired volunteers.

“We did a couple of different tests with blind users,” says Robert Katzschmann, a graduate student in mechanical engineering at MIT and one of the paper’s two first authors. “Having something that didn’t infringe on their other senses was important. So we didn't want to have audio; we didn’t want to have something around the head, vibrations on the neck — all of those things, we tried them out, but none of them were accepted. We found that the one area of the body that is the least used for other senses is around your abdomen.”

Katzschmann is joined on the paper by his advisor Daniela Rus, an Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science; his fellow first author Hsueh-Cheng Wang, who was a postdoc at MIT when the work was done and is now an assistant professor of electrical and computer engineering at National Chiao Tung University in Taiwan; Santani Teng, a postdoc in CSAIL; Brandon Araki, a graduate student in mechanical engineering; and Laura Giarré, a professor of electrical engineering at the University of Modena and Reggio Emilia in Italy.

Parsing the world

The researchers’ system consists of a 3-D camera worn in a pouch hung around the neck; a processing unit that runs the team’s proprietary algorithms; the sensor belt, which has five vibrating motors evenly spaced around its forward half; and the reconfigurable Braille interface, which is worn at the user’s side.

The key to the system is an algorithm for quickly identifying surfaces and their orientations from the 3-D-camera data. The researchers experimented with three different types of 3-D cameras, which used three different techniques to gauge depth but all produced relatively low-resolution images — 640 pixels by 480 pixels — with both color and depth measurements for each pixel.

The algorithm first groups the pixels into clusters of three. Because the pixels have associated location data, each cluster determines a plane. If the orientations of the planes defined by five nearby clusters are within 10 degrees of each other, the system concludes that it has found a surface. It doesn’t need to determine the extent of the surface or what type of object it’s the surface of; it simply registers an obstacle at that location and begins to buzz the associated motor if the wearer gets within 2 meters of it.

Chair identification is similar but a little more stringent. The system needs to complete three distinct surface identifications, in the same general area, rather than just one; this ensures that the chair is unoccupied. The surfaces need to be roughly parallel to the ground, and they have to fall within a prescribed range of heights.

Tactile data

The belt motors can vary the frequency, intensity, and duration of their vibrations, as well as the intervals between them, to send different types of tactile signals to the user. For instance, an increase in frequency and intensity generally indicates that the wearer is approaching an obstacle in the direction indicated by that particular motor. But when the system is in chair-finding mode, for example, a double pulse indicates the direction in which a chair with a vacant seat can be found.

The Braille interface consists of two rows of five reconfigurable Braille pads. Symbols displayed on the pads describe the objects in the user’s environment — for instance, a “t” for table or a “c” for chair. The symbol’s position in the row indicates the direction in which it can be found; the column it appears in indicates its distance. A user adept at Braille should find that the signals from the Braille interface and the belt-mounted motors coincide.

In tests, the chair-finding system reduced subjects’ contacts with objects other than the chairs they sought by 80 percent, and the navigation system reduced the number of cane collisions with people loitering around a hallway by 86 percent.

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Danielle Olson: Building empathy through computer science and art

Communicating through computers has become an extension of our daily reality. But as speaking via screens has become commonplace, our exchanges are losing inflection, body language, and empathy.

Danielle Olson ’14, a first-year PhD student at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), believes we can make digital information-sharing more natural and interpersonal, by creating immersive media to better understand each other’s feelings and backgrounds.

Olson’s research focuses on inventing and analyzing new forms of media, from gaming experiences to interactive narratives. Last year she worked with Fox Harrell, an associate professor of digital media with appointments in the MIT Comparative Media Studies/Writing program and CSAIL, and Karim Ben Khelifa, a photojournalist and MIT visiting artist, on “The Enemy,” a virtual reality experience that lets users stand “face-to-face” with soldiers from opposing sides of global conflicts.

Khelifa traveled to places such as Israel, Palestine, and El Salvador to interview soldiers from different sides of conflicts. Olson’s contribution was to help design algorithms that analyzed their body language for how they would move in different scenarios. That information was then incorporated into the live experience: If the user walks towards one of the soldiers, the soldier can dynamically respond based on the user’s behavior.

She says that the goal of “The Enemy” is to enable the public to develop more meaningful relationships to world events than they would simply by reading news articles.

“You’re looking someone in the eye as they describe death and war conflicts, and seeing their facial expressions and body language,” Olson says. “There's a different level of empathy that you can cultivate with these sorts of technologies.”

Her other areas of research follow a similar thread of building empathy by examining different cultures. She’s working on developing interactive narrative experiences to help kids practice dealing with social identity issues. For example, one game might involve an elf trying to get past a gate keeper from a different clan, who may try fitting in by downplaying parts of their identity to get past the gate. Olson’s work has already gained attention from notable artists such as rapper Lupe Fiasco, who came into Harrell’s lab at MIT to offer feedback.  

Growing up, Olson got a late start to coding. As a kid she wasn't one to play video games or pull apart computers, and didn't even know what MIT was until she watched “Iron Man” as a high-schooler. At 17 she was accepted to MIT's Minority Introduction to Engineering and Science Program (MITES) program, and she returned the following year as an undergraduate.

She says that her passion for education comes from her mother, who came to the U.S. from Cameroon with only an eighth-grade education before going on to earn her master’s degree.

“I always hear my mom’s voice saying that education is the one thing nobody can take away from you,” Olson says.

As an MIT senior she founded Gique, a nonprofit focused on teaching local students skills in STEAM — science, technology, engineering, arts, and math — embracing the intersection of art and technology. Her team creates hands-on curricula, experiments, and activities to help students develop more holistic viewpoints of the world.

“A 2008 study on ‘No Child Left Behind’ showed that half of the nation's districts decreased class time for art, drama, history, and science, which left students with a narrow learning environment,” she says. “We need to fight back against policies that discourage interdisciplinary education.”

Olson says that it’s vital for people in power to use their influence to help give underrepresented groups more access to resources that can level the playing field. 

“I had access to programs like FIRST Robotics and MITES because I didn’t have to pay for them,” she says. “They’re sponsored by people who put their money where their mouth is and who aren’t just acknowledging the need for workplace diversity: They’re actually taking steps to invest directly in people of color."

Outside of her research and educational work, Olson feeds her creative pursuits, whether it’s cooking, reading comic books, or taking care of her pet rabbit and cat.

“I see my place as raising the next generation of computer science warriors who ingrain their culture into the fabric of computing,” she says. “I think it’s important to build systems that aren’t catered only to certain populations, but actually represent many values and bolster our political capital as developers, engineers, and makers.”

Fast Facts

Favorite place for news: Twitter

One thing people would be surprised to know about her: She was an MIT cheerleader. The year she started and served as co-captain was the first time in MIT history that the cheerleading team went to nationals.

Advice to incoming students: “You’re going to have failures. The master has failed more times than the beginner has even tried. Make sure you have an identity outside of research, so it’s not threatened when you hit a bump in the road.”

Her tech role model: Stacie LeSure Gregory, a postdoc at the American Association of University Women (AAUW). “She’s dedicated her career to empowering women and underrepresented groups in STEM.”

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MIT Press teams with Internet Archive and Arcadia to provide access to hundreds of backlist titles

The MIT Press and the Internet Archive have announced a partnership, with support from Arcadia, to scan, preserve, and enable libraries to lend hundreds of MIT Press books that are currently not available digitally. This partnership represents an important advance in bringing acclaimed titles across the MIT Press’ publications in science, technology, art, and architecture to a global online audience.  

The joint initiative is a crucial early step in Internet Archive’s ambitious plans to digitize and provide public access to 4 million books, by partnering widely with university presses and other publishers to source print works, and enable readers to borrow the digital versions from any library that owns the physical book, as well as from archive.org.  

“These books represent some of the finest scholarship ever produced, but right now online learners cannot unlock this knowledge,” says Brewster Kahle, founder and digital librarian of the Internet Archive. “Together with the MIT Press, we will enable the patrons of every library that owns these books to have a choice. They can read the physical book or the electronic version of these important texts.”  

The Internet Archive is one of eight groups named semi-finalists in 100&Change, a global competition for a single $100 million grant from the John D. and Catherine T. MacArthur Foundation. The competition seeks bold solutions to critical problems of our time. The partnership with MIT Press is part of an ambitious plan to create more universal and equitable access to knowledge worldwide, bringing some of the most important books of the 20th century to scholars, journalists, students, and the print disabled.

MIT Press Director Amy Brand says, “One of my top ambitions for the MIT Press since becoming director just two years ago has been to ensure that our entire legacy of publications is digitized, accessible, searchable, discoverable now and in perpetuity. Partnering with Internet Archive to achieve this objective is a dream come true not only for me and my colleagues at the press, but also for many of our authors whose earlier works are completely unavailable or not easily accessible.”  

“Lending online permits libraries to fulfill their mission in the digital age, allowing anyone in the world to borrow through the ether copies of works they own,” said Peter Baldwin, co-founder of Arcadia and professor of history at the University of California at Los Angeles. “The IA-MIT collaboration is a big step in the direction of realizing a universal library, accessible to anyone, anywhere.”

The MIT Press-Internet Archive partnership is the MIT Press’ first major digitization endeavor. It ushers in a new era of access for readers who value the press’ distinctive position as a university press that honors real world complexity by publishing interdisciplinary scholarship that crosses traditional boundaries.

An initial group of 1,500 MIT Press titles will be scanned at Internet Archive’s Boston Public Library facility, including Cyril Stanley Smith’s 1980 book, "From Art to Science: Seventy-Two Objects Illustrating the Nature of Discovery," and Frederick Law Olmsted and Theodora Kimball’s "Forty Years of Landscape Architecture: Central Park," which was published in 1973. The oldest title in the group is Arthur C. Hardy’s 1936 "Handbook of Colorimetry."

John Palfrey, head of school at Phillips Academy Andover and well-known public access advocate, described the partnership as “a truly ground-breaking development in open scholarship that I hope will inspire other university presses to follow suit, since so many excellent and important books are effectively out of circulation by virtue of being analog-only in a digital world.”

The Internet Archive has already begun digitizing MIT Press’ backlist and anticipates lending copies as early as next month. The entire backlist should be available by the end of 2017.

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Internet of things: Let the avatars talk to each other

On the 25th anniversary of the universal barcode in 1999, the barcode community gathered around Sanjay Sarma and his colleagues and said, “Let’s do this.”

“Our idea,” says Sarma, vice president for open learning and the Fred Fort Flowers (1941) and Daniel Fort Flowers (1941) Professor of Mechanical Engineering at MIT, “was to track everything in the supply chain.” Some companies knew they had too much inventory. Others didn’t know where their inventory was. Consumers couldn’t find the right sized shirt while that shirt was sitting in the back room. Food was going bad and shelves went un-stocked. Things got lost in the supply chain. So, Sarma, along with research scientist David Brock of MIT and Kevin Ashton, a visiting researcher from Proctor and Gamble, came up with a low-cost radio frequency identification (RFID) tag. “At the time, it was a crazy idea,” says Sarma. “But it stuck.”

RFID tags, which had been around for several decades, were clunky and expensive — partly because of the amount of data placed on the tags. “We used to say, ‘Someday the internet will be everywhere’ — this was late 90s — and we didn’t have the word 'cloud' yet. So, we used to say, ‘Someday, you can write the data in the sky,’” says Sarma, who developed new standards for RFID, new manufacturing processes, and innovative ways to use them in the supply chain. The supply chain industry adopted the protocol, and standards-making efforts shifted. Auto ID Labs laid the groundwork for the standardization of RFID technology. It took sensing of identity — the job of RFID and barcodes — and made it universal. Auto ID Labs, where Sarma remains active today, emerged from the MIT Auto ID Center. “In many ways that effort also laid the groundwork for what is now called the internet of things,” Sarma says.

Internet of things

“If you look at the world today, you may have a Nest Thermostat in your home; you may have an Amazon Echo in your home; if you’re lucky enough to own a Tesla car, you can actually track your Tesla car over the internet. More appliances are becoming fundamentally internet-connected and intelligent in ways that make our lives safer, the world safer, help with climate change, help with saving costs, help with better health care,” says Sarma. All of this comes from a network of objects embedded in intelligence that interact with the environment. That is called the internet of things.

“When we start connecting things,” says Sarma, “we enable a level of resource management, a level of marshalling of the planet, of what the planet offers us. When we have little or no information on something, we over-compensate. We burn more electricity, more energy and we’re doing more damage to the planet.” He asserts that hundreds of rooms are consuming electricity they should not, that are heating when no one is there. If you knew that a person was still driving and that there’s no need to turn the heat on, just imagine how much energy one could save and what impact this technology would have on the planet. “To me, saving the planet is sort of an existential question and we have an enormous amount of work to do to do that,” Sarma explains.

Risks, norms, and rules

With any new technology, there are risks. The first and most fundamental one for the internet of things is privacy. “If I have a Nest Thermostat in my house, I can turn the heating off when I’m not at home. If I forget to turn off the heat when I go on vacation, it can detect that I’m away and turn itself off.” The flipside is that it can tell the wrong person you’re not there, thereby increasing the risk of theft and burglary. A sort of extreme version of that, he explains, is a malicious party claiming control of a nuclear power plant. This is the great fear of the internet of things: Many people are adopting it and they’re moving fast, but they’re not thinking about security, and that is a recipe for disaster. “My research deals with balancing the two,” Sarma says.

In any system with an agreed-upon architecture and with easy-to-understand methods, safeguards and security can be built into the system. “Imagine if you were concerned about safety on the roads — and we did have those worries a hundred years ago,” says Sarma. Over time, certain standards are implemented. “In the U.S. we drive on the right side of the road; we have traffic lights; we have stop signs; we have behavioral norms. If a parent and a child want to cross the street at a crosswalk, traffic stops. If a school bus in front of you flashes its lights, you stop. These behavioral norms — these standards — help recognize when something goes awry.” Sarma explains that if one of these behavioral norms is broken, one can deduce that the driver’s eyesight isn’t good, or that they weren’t paying attention, or maybe they were texting, or maybe that person is malicious.

The problem with the internet of things is that within this newly established world, there are few norms. When different people implement it in their own way, it’s very hard to detect malice, he says. It’s also hard to put together a protection. Unlike the road systems, in which there are police cars and cameras, “we don’t have any of those. The internet of things is the wild west. My own research is directed toward establishing those norms and rules, so that at least you have some orderliness, so the remnant disorderliness stands out and can be detected.”

Avatar

One protection Sarma and his team are promoting is something called the avatar, a cloud-things concept. “The basic idea we’re saying is don’t have Object A talk to Object B, have Object A talk to its cloud avatar of itself. Have Object B talk to its Cloud Avatar of itself. Then, have the Avatars talk to each other.” The reason it works is because physical connections between A and B are many. “If you just say, the real object only talks to its avatar and the avatars talk to each other, we can bring to bear all the stuff we know from the WorldWideWeb, etc. That’s a clean way to look at the future of the internet of things and, strangely enough, that’s what Tesla does, that’s what Nest does, but unfortunately implementations are a little bit all over the place,” he says.

“The internet of things will go through its ups and downs, but when we look back on our lives in 10 years, pretty much anything you do you’ll back on a day when it wasn’t connected and you’ll sort of wonder how life was then.”

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MIT Video Productions nominated for New England Emmy Award

MIT Video Productions (MVP), formerly known as Academic Media Production Services (AMPS), received its second New England Emmy Award nomination for its documentary, "A Bold Move," in the education/schools category. In 2014, MVP was nominated and won the award for its work in the category of arts and entertainment.

The first in a four-part series of documentaries produced in celebration of MIT’s 100th year in Cambridge, Massachusetts, "A Bold Move" tells the story of the visionaries, led by the newly appointed President Richard Cockburn Maclaurin, who spearheaded the Institute’s relocation from Boston to Cambridge in 1916. The 17-minute film details the challenges and aspirations of the era, and explores the innovative design of MIT’s vast set of interconnected buildings known as the Main Group, which would have an enormous impact on science, technology, and education in the years that followed. Referred to as the “mega building,” it was the first MIT structure architected to foster cross-disciplinary research and education, which remains one of the Institute’s hallmarks.

“'A Bold Move' is emblematic of the many spectacular stories to be told about MIT’s history, from its well-known excellence in research and engineering to its lesser-known, but equally bright, distinction in the humanities, arts, and social sciences,” said Larry Gallagher, executive producer and senior director of MIT Video Productions. “At MVP, we are honored to shine a light on the Institute’s many areas of excellence with work that reflects the overall richness of the MIT experience.”

The underlying narrative of "A Bold Move" is about far more more than constructing a new campus; it’s about a broad vision and what it symbolized. “MIT isn’t just building a new set of buildings to accommodate its space constraints, it’s building a new set of buildings to make a statement to the world about the importance of science and technology education,” says Deborah Douglas, curator of science and technology at the MIT Museum.

"A Bold Move" and the other documentaries in the series feature a variety of MIT faculty, students, and staff as well as members of the Cambridge community, including city officials and historians. Nearly every member of the MVP team contributed to the production of the film, led by producer/director Joe McMaster and editor/co-producer Jean Dunoyer ’87. Prior to joining the MVP team, McMaster and Dunoyer honed their storytelling skills making documentaries for PBS and National Geographic, among others. The production of MVP’s Emmy Award-nominated program was supported in part by a generous gift from Jane and Neil Pappalardo ’64.

Winners of the education/schools award will be announced June 24 at the 40th Annual New England Emmy Awards in Boston.

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MIT receives Massachusetts Breastfeeding Coalition's Breastfeeding-Friendly Employer Award

The Massachusetts Breastfeeding Coalition (MBC) has recognized MIT as a breastfeeding-friendly employer for its active support of employees who want to continue breastfeeding when they return to work.

Several working mothers at MIT nominated the Institute for the MBC award. Nominators were asked to provide information on the following criteria:

• availability of a private space for employees to pump or express breast milk or nurse their babies;
• flexibility for employees to bring young babies to work with them;
• regular break times or a more flexible work schedule to facilitate pumping and nursing;
• access to an electric breast pump;
• a refrigerator for storage of expressed breast milk, and sink area for cleaning equipment; and
• information on workplace breastfeeding support services for all employees.

In awarding the designation, MBC lauded MIT for having a “great support system."

MIT will be recognized for its achievement at MBC's Breastfeeding in the Bay State 2017 conference in September.

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Exploring elusive high-energy particles in an unusual metal

Mid-infrared wavelengths of light are invisible to the eye but can be useful for a number of technologies, including night vision, thermal sensing, and environmental monitoring. Now, a new phenomenon in an unconventional metal, found by physicists at MIT and elsewhere, could provide a new way of making highly sensitive detectors for these elusive wavelengths. The phenomenon is closely related to a particle that has been predicted by high-energy physicists but never observed.

Physicists group all the fundamental particles in nature into two categories, fermions and bosons, according to a property called spin. The fermions, in turn, have three types: Dirac, Majorana, and Weyl. Dirac fermions include the electrons in regular metals such as copper or gold. The other two are unconventional particles that can give rise to strange and fundamentally new physics, which potentially can be used to build more efficient circuits and other devices.

The Weyl fermion was first theorized almost a century ago by German physicist Hermann Weyl. Even though its existence is posited as part of the equations that form the widely accepted Standard Model of subatomic physics, Weyl fermions have never actually been observed experimentally. The theory predicts that they should move at the speed of light, and, at the same time, spin about the direction of motion. They come in two varieties depending on whether their rotation around the direction of motion is clockwise or counterclockwise. This property is known as the handedness, or chirality, of Weyl fermions.  

Even though Weyl fermions have never been observed directly, researchers have recently observed a phenomenon that mimics essential aspects of their theorized properties, in a class of unconventional metals known as Weyl semimetals. One remaining challenge was to experimentally measure the chirality of these Weyl fermions, which evaded detection from most standard experimental techniques.

In a paper published in the journal Nature Physics, an MIT team was able to measure Weyl fermion chirality by using circularly polarized light. This work was done by MIT postdocs Qiong Ma and Su-Yang Xu; physics professors Nuh Gedik, Pablo Jarillo-Herrero, and Patrick Lee; and eight other researchers at MIT and other universities in the U.S., China, and Singapore.

Specifically, the researchers found that a metal called tantalum arsenide, or TaAs, “exhibits an interesting optoelectronic property called the circular photogalvanic effect,” says Gedik, an associate professor in the Department of Physics. Conventionally, electrical conduction requires applying an external voltage across the two ends of a metal (such as copper). By contrast, the researchers found in this work that, by shining circularly polarized light in the mid-infrared wavelength range, the TaAs can produce an electrical current without applying external voltages. Moreover, the direction of the current is dictated by the chirality of Weyl fermions and can be switched by changing the light polarization from left-handed to right-handed.

The amount of current generated in this way turns out to be surprisingly large — 10 to 100 times stronger than the response of other materials used for detecting this kind of light. This could make the material useful for extremely sensitive light detectors in this mid-infrared part of the spectrum.

“Despite being predicted a long time ago, Weyl fermions have never been observed as a fundamental particle in particle physics,” Gedik explains. But the new experiments, he says, have shown that in these unconventional metals, ordinary electrons “can behave in a strange way so that their motion mimics the behavior of Weyl fermions,” and can exhibit a range of novel properties.

Over the years since Weyl’s original hypothesis, “Lots of people suspected that neutrinos were Weyl fermions,” Xu says. Neutrinos are subatomic particles that hurtle through the universe at nearly the speed of light and were long thought to have no mass at all, just like the posited Weyl fermions. But then, when it was discovered that neurinos did in fact have a tiny but measurable mass, that possibility was ruled out, and actual Weyl fermions have still never been observed. “But the way the behavior of electrons in semimetals such as TaAs closely mimics what was predicted for Weyl fermions lends support to Weyl’s original theory,” Ma says.

Electrons “can behave like Weyl fermions in those metals,” Ma says. “They always come in pairs that always have opposite chirality.”

While others had observed some of the unusual behavior of electrons in these materials, nobody had previously been able to probe the key aspect of the Weyl fermions, namely their left- or right-handed spin. But in this research, “we figured out a way to measure the chirality,” Xu says, by using circularly polarized light to trigger the electrical current, and showing that opposite light polarizations caused the current to move in opposite directions. By measuring the current using electrodes attached to the material for different light polarizations, they were able to deduce the chirality of Weyl fermions responsible for this current.

“The significance of this work is that this is the first-ever direct observation of the chirality of Weyl fermions,” says Anton Burkov, associate professor of physics and astronomy at the University of Waterloo, in Canada, who was not involved in this work. “The chiral charge of Weyl fermions does have other direct consequences, like the Fermi arc edge states, but one would like to measure this property directly in electromagnetic response. This work reports the first such measurement.”

The research team also included former postdoc Ching-Kit Chan (now assistant adjunct professor at the University of California at Los Angeles); graduate student Yuxuan Lin; Associate Professor Tomas Palacios and the William and Emma Rogers Professor Patrick Lee at MIT; Chen-Long Zhang and Assistant Professor Shuang Jia at Peking University in China; Guoqing Chang and Assistant Professor Hsin Lin at the National University in Singapore; and Assistant Professor Weiwei Xie at Louisiana State University. The work was supported by the U.S. Department of Energy, the Gordon and Betty Moore Foundation, and the National Science Foundation.

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Media Lab announces 2017 Director’s Fellows

When the MIT Media Lab Director’s Fellows initiative launched in 2013, the goal was to connect people from across the world with the innovation and creativity of the Media Lab. Five years later, this global network now includes 38 current and former fellows from a range of disciplines — artists and designers, scientists and technologists, advocates and activists, dancers and musicians, writers and comedians, athletes, filmmakers, scientists, and more.

In July, nine new Fellows will join the growing group.

“The latest cohort of Director’s Fellows aligns with our mission to create a better future for all, addressing pressing issues through the lens of civic engagement, social change, education, and creative disruption,” says Media Lab Director Joi Ito. “Not only do the fellows bring their own expertise from different fields but they also take what they learn from their involvement and collaborations in the program back to the world beyond.”

Meet the 2017 Director’s Fellows:

Julia Angwin is a senior reporter at ProPublica. As an investigative journalist at The Wall Street Journal, she was on a team of reporters who won a 2003 Pulitzer Prize in explanatory reporting for coverage of corporate corruption, and in 2011 Angwin led a privacy investigative team that was a Pulitzer finalist. The Newswomen’s Club of New York named her reporter of the year in 2014.

Farai Chideya has combined media, technology, and sociopolitical analysis during her 20-year career as an award-winning author, journalist, professor, and lecturer. She’s currently a fellow at Harvard University's Shorenstein Center on Media, Politics, and Public Policy, studying newsroom diversity and media coverage of the 2016 election.

Isha Datar has been a pioneer in the emerging field of cellular agriculture since 2009 when she began investigating the technical challenges and opportunities in producing cultured meat. In her quest to establish the field of animal products made without animals, she discovered that the research was held back — not by a lack of interest or expertise, but by a lack of funding channels for this intersectional work.

Adam J. Foss is a former assistant district attorney in the Juvenile Division of the Suffolk County District Attorney’s Office in Boston. Now an advocate for criminal justice reform, he co-founded Prosecutor Impact, emphasizing that the profession is ripe for reinvention based on improved incentives and more measurable metrics for success beyond “cases won.”

Andrea Lauer is the founder and chief creative officer of Risen from the Thread, a design-thinking, product development, and innovation agency focused on the human body and its relationship with technology. She lectures at universities and works internationally to produce multi-media experiences with a focus on the human form.

Leland Melvin is a former NFL draftee who became an engineer and a NASA astronaut logging more than 565 hours aboard the shuttle Atlantis. Melvin was appointed the head of NASA Education in 2010 and served as co-chair of a White House STEM task force. He currently hosts the television series "Child Genius" and is a judge on the TV series "BattleBots."

Jamila Raqib is a nominee for the 2017 Nobel Peace Prize. She’s executive director of the Albert Einstein Institution, which promotes the study and strategic use of nonviolent action worldwide. Her work centers on presenting a pragmatic approach to nonviolent action to activists and organizers, human rights organizations, academics, and government bodies. As a research affiliate at the MIT Media Lab, Raqib has been exploring how innovations in technology and education can contribute to more effective nonviolent strategies.

Esra’a Al Shafei is a Bahraini human rights activist and founder of Majal.org, an organization that develops platforms to amplify underrepresented and marginalized voices in the Middle East and North Africa. Al Shafei has received the Berkman Award for “outstanding contributions to the internet and its impact on society,” and Fast Company featured her as one of the “100 Most Creative People in Business.”

Gavin Zhao has deep experience in supply chain management for startup companies. In 2010, he joined AQS, a firm that provides electronics manufacturing and engineering solutions around the world. Zhao leads strategic planning and specializes in helping suppliers to overcome manufacturing difficulties in new projects.

The 2017 Director’s Fellows officially join the Media Lab on July 19. They did not apply for the program; rather, they were nominated by a network of advisors. Many factors go into the selection process, including all aspects of diversity, each fellow’s balance with the rest of the cohort, and the impact of their work in the world.

What’s pivotal to the program is that the fellows collaborate both with each other and with Media Lab faculty, researchers, and students. They get involved in a variety of activities — from leading workshops, to participating in research projects, to advising on students’ theses. And, they often find there’s so much to do that their two-year honorary affiliation extends beyond the time they’re officially part of the Director’s Fellows group.

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In search of the fundamental laws of microecology

Model microorganisms grown in pure cultures have been the basis of biological research for many decades — open a cell biology textbook and almost everything you will find has been discovered in yeast or E. coli lab cultures. While this speaks to the power of research on individual species, ecologists would be quick to remind us that pure cultures rarely exist in nature. Organisms live in an ecological context, and are often cogs in a well-oiled ecological machine with multiple species.

Microbial communities are one prime example of ecological systems that are far from being pure cultures, and these communities play fundamental roles in earth’s ecosystems. Despite their critical contributions to our world, our understanding of these collective systems lags decades behind our knowledge of pure cultures. The rules that govern their dynamics and function also remain largely unknown.

Now, a new Simons Foundation collaboration called Theory of Microbial Ecosystems (THE-ME, pronounced "theme") is attempting to fill this gap by discovering the principles of how microbial communities form and function.

Simons Collaborations like THE-ME are large-scale projects that bring together funded investigators from difference disciplines to find solutions to major scientific problems, such as the origin of life or the coding of information in the brain. THE-ME is being launched by a multidisciplinary team of researchers from across the United States and Europe, coordinated by MIT Department of Civil and Environmental Engineering Assistant Professor Otto X. Cordero and Professor Roman Stocker of ETH Zurich. They hope the effort will result in the development of fundamental quantitative theories that can help us understand and predict the behavior of microbial ecosystems.

“Some of the biggest open questions in biology remain at the level of collectives,” Cordero says. “Cells have evolved internal regulatory programs that allow them to sense their environment and adjust their behavior. By contrast, ecological communities lack any form of centralized control, they are distributed and decentralized systems. How such systems self-organize in a reproducible fashion in the absence of a central conductor is one of the most important questions in biology.”

THE-ME seeks to answer three central questions about microbial communities: how microbes in communities organize and distribute roles, how communities utilize resources for energy and growth, and how they respond to environmental disturbances and changes.

Cordero and Stocker, both environmental scientists, assembled a research team that will take a multidisciplinary approach to answering these questions. Their strategy is to develop model systems to study the interaction between cellular processes and community-level processes. The researchers hope to use these findings to discover quantitative laws that dictate the behavior of such microbial ecosystems.

To develop these model systems, the team of researchers will draw inspiration from the ocean, where communities of bacteria self-organize at micrometer scales to degrade particles of organic matter. One of the major benefits of studying oceanic microbes is their ecological relevance — by recycling organic matter these organisms drive the cycling of carbon in the planet. Moreover, new technology now allows scientists to recreate their microenvironments at microscales in the laboratory, allowing researchers to study their dynamics and function in synthetic ecosystems.

“Many of the major discoveries in microbial ecology took place in the context of marine microbes and, incidentally, in the Parsons Lab at MIT, which has a great tradition of pioneering microbial ecology research. We hope to continue and build from that tradition,” Cordero says.

In addition to Cordero and Stocker, the THE-ME research team includes Jeff Gore, a biophysicist and associate professor of physics at MIT; Mick Follows, professor of earth, atmospheric and planetary sciences at MIT; Martin Ackermann, a professor of molecular microbial ecology at ETH Zurich; and Sebastian Bonhoeffer, a theoretical biologist and professor at ETH Zurich. Also working with the team are Victoria Orphan, a molecular microbial ecologist and professor at Caltech; Mary Ann Moran, a marine microbiology and professor at University of Georgia; Terence Hwa PhD ’90, a theoretical physicist and professor at University of California at San Diego; and Naomi Levine PhD ’10, an ocean modeling theoretical ecologist and assistant professor at University of Southern California.

“Roman and I were looking for researchers that are at the top of their fields and had a strong quantitative background,” Cordero says. “Most importantly, we had to find people that could work well together. I think we have assembled an amazing team of scientists and we are looking forward to getting this project underway. I’m confident this cross-continental, cross-institutional project will prove extremely valuable.” 

“The Simons Foundation truly makes large-scale research possible,” he adds. “We are extremely grateful for the foundation for funding THE-ME. The projects and experiments we are planning are foundational to microbiology and we appreciate the support of the Simons Foundation for our research endeavors.” 

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New method enables real-time monitoring of materials during irradiation

A new advance on a method developed by MIT researchers could enable continuous, high-precision monitoring of materials exposed to a high-radiation environment. The method may allow these materials to remain in place much longer, eliminating the need for preventive replacement. It could also speed up the search for new, improved materials for these harsh environments.

The new findings appear in the journal Applied Physics Letters, in a paper by graduate student Cody Dennett and assistant professor of nuclear science and engineering Michael Short. This study builds on the team’s earlier work that described the benchmarking of the method, called transient grating spectroscopy (TGS), for nuclear materials. The new research shows that the technique can indeed perform with the high degree of sensitivity and time-resolution that the earlier calculations and tests had suggested should be possible for detecting tiny imperfections.

“Our whole goal was to monitor how materials evolve when exposed to radiation,” Short explains, “but do it in a way that’s online,” without requiring samples to be extracted from that environment and tested in outside devices. Such a process can be time-consuming and expensive, and doesn’t provide information about how damage occurs over time.

The new testing approach can reveal changes in, for example, thermal and mechanical properties that affect the material’s response to temperature surges or vibration. “What we’re working toward is a real-time diagnostic system that works under radiation conditions,” Short says.

Their earlier work, he says, showed that the technique was capable of detecting such radiation-induced changes. The new work, which included making some modifications to the method, makes it possible to take measurements at high speed under real-time, dynamic conditions, and to produce the kind of detailed information needed for a practical monitoring system.

The method works without requiring any physical contact between the monitoring device and the metal surfaces being monitored. Instead, it relies purely on optical probes, which use one set of laser beams to stimulate vibrations in the surface, and others to probe the properties of those vibrations by using the interference patterns of the beams, which can reveal details not just of the surface properties but of the bulk material, as well.

The technique could also have broad applications in monitoring other kinds of materials, the researchers say. For example, it could be used to monitor the behavior of phase-change materials that are being developed for new kinds of magnetic data storage. “The ability to do characterization of dynamically changing systems is of interest to a wider materials processing community,” Dennett says. Since the team published details of the initial work, researchers around the world have contacted the researchers with requests for help with applying the technique to different kinds of materials and environments.

“We have particular applications in mind for our next steps,” Dennett says, “but the relative ease of implementation should make it interesting to a wide range of materials scientists.”

Compared to existing methods of studying these radiation-induced materials’ changes, which involve using multiple samples exposed over long periods of time before testing, Short says, this technique can provide “more data from one sample, in one experiment, in about 1 percent of the time.”

That ability to do rapid testing could be a significant boon for those attempting to develop new materials for new generations of nuclear reactors, Dennett says. Now, such development is a slow and painstaking process, because even tiny changes in the relative percentages of different alloying metals can dramatically affect the material’s properties. The new technique’s ability to provide rapid, real-time answers could open up much broader possibilities for developing and refining new options.

“There are a lot of groups working on more radiation-resistant alloys,” Short says, “but it’s a long process. Instead, this allows you to make a lot of variations and test them as you go.” This method could allow these researchers to come up with significant characterization data on new materials “in weeks instead of years,” he says.

The research was supported by the National Science Foundation, the U.S. Department of Energy’s National Nuclear Security Administration, and the MIT-Singapore University of Technology and Design International Design Center.

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New scaling law predicts how wheels drive over sand

When engineers design a new aircraft, they carry out much of the initial testing not on full-sized jets but on model planes that have been scaled down to fit inside a wind tunnel. In this more manageable setting, they can study the flow of air around an aircraft under all manner of experimental conditions.

Scientists can then apply scaling laws — mathematical relationships of proportionality — to extrapolate how a full-size jet would perform, based on the behavior of its miniature counterpart.

Now engineers at MIT have come up with a similar scaling law to describe how objects move through sand. The scaling law can be used to predict how large trucks and cars drive through this material, based on how toy versions of those vehicles drive through an experimental sandbox containing the same grains.

Ken Kamrin, associate professor of mechanical engineering at MIT, says the scaling law may enable a wide range of small-scale experiments to hone the design of large-scale vehicles, such as more optimized tractors, bulldozers, and tanks. It might also be applied to translate a vehicle’s locomotion on Earth to a rover’s navigation on Mars, because the relation allows for the scaling of gravity as well.  

“I’m excited that this could be a new tool we can use to design rovers for Mars,” Kamrin says. “If we had a simulant of Martian soil in the lab, we could do experiments with a wheel shape that we want to test, and then use this scaling law to, with more accuracy, be able to tell you if that wheel would get stuck on Mars.”

Kamrin has published a paper detailing the scaling law in the journal Physical Review E. His co-authors are former graduate student James Slonaker, former undergraduate D. Carrington Motley, graduate student Qiong Zhang, undergraduate student Stephen Townsend, former research scientist Carmine Senatore, and principal research scientist Karl Iagnemma.

Giving backbone to scaling

Aircraft engineers typically use scaling laws to, for example, determine the minimum force of lift required to keep a full-sized jet aloft, based on the same minimum lift for a model plane. Such scaling laws are initially derived from physics-based equations that describe the way a fluid, such as air, behaves.

“The thought is, if you can identify scalings within the fluid flow equations, they can be used as an immediate way of translating between small- and large-scale results,” Kamrin says.

His team looked for ways to derive a scaling law from common equations for granular flow. They first looked to a generalized set of equations, known as resistive force theory (RFT), which is used to calculate the resistive force on an object moving through a bed of grains such as sand.

“RFT is not going to predict how sand moves or distributes stress,” Kamrin says. “Its sole purpose is to tell how much force is needed to move an object of an arbitrary shape, in a certain direction, through sand.”

The researchers sought to simplify the RFT formula by making many of its inputs dimensionless, or without units.

“This ultimately lets us extract the scaling relations,” Kamrin says. “For example, ‘meters’ is not a natural length — it’s something we invented. If we get rid of all these units, we will be left with the meat, some truth to the system.”

Kamrin’s team used Buckingham’s theorem, the backbone of mathematical scaling, to winnow certain variables in RFT, such as an wheel’s length, width, and mass, into dimensionless parameters, thereby simplifying the overall equation. The idea is that, by deriving an equation that is not dependent on certain units, that same equation can be used to produce rules for how to translate between scales of the same system.

After deriving a scaling law from RFT, the researchers looked to see whether they could do the same with another set of granular flow equations, a continuum model based on frictional yielding. These much more detailed equations describe the flow of sand and the force that it creates as it pushes against an intruding object such as a wheel. Even for these more complex equations, the team found it was able to derive a scaling law that matched the one it developed from the simpler RFT model.

“Turns out they both gave the same answer, so we thought maybe this [scaling law] will work,” Kamrin says.

Driving tests

To test the scaling law, Kamrin and his colleagues performed experiments in MIT’s Robotic Mobility Group lab, where engineers have set up a rail and pulley system that supports a motorized wheel as it drives through an underlying sand bed. Kamrin’s team used a 3-D printer to construct small and large versions of two different wheel shapes: a typical cylindrical design and a “lug” wheel with four arms extending from a central cylinder.

The two shapes were chosen to demonstrate two distinct driving behaviors, as cylindrical wheels drive smoothly with limited sinkage, while lug wheels dig through and remove pockets of sand as they drive. 

The researchers measured each wheel’s dimensions and loaded them up with varying amounts of weights, then drove each wheel through the sand bed one at a time, noting the power and speed of the small wheels compared with their larger counterparts.

They performed 288 such experiments, each time varying the wheel’s dimensions, rotation speeds, and masses. They then used their scaling law to see whether they could predict the large wheels’ velocity and power, based on their smaller versions’ performance.

“Our data followed the predictions,” Kamrin says. “The small tests predicted the big tests, to a quantitative degree. We validated many times over the accuracy of the scaling law.”

Going forward, the team says its scaling law can be used to design vehicles that can better navigate sandy terrain.  

“Think of bulldozers, excavators, all these things that need to manipulate and move granular material around,” Kamrin says. “These aren’t really optimized. A lot of equipment used in industry is based on rules of thumb, but results like this could provide a new kind of tool to help pinpoint the best designs.”

This research is supported, in part, by the Army Research Office and the National Science Foundation.

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Chemists reveal amyloid structure

Amyloids are clumps of protein fragments that stick together to form stringy fibrils such as the plaques seen in the brains of Alzheimer’s patients. Many of these proteins bind to metals such as zinc, but the structure of these metal-bound proteins has been difficult to study. The importance of these metals to the activity of amyloids thus remains an open question, which is all the more perplexing because some amyloids are associated with disease but others are not.

A team of MIT chemists, working with researchers at the University of California at San Francisco (UCSF) and Syracuse University, has now deciphered the structure of an amyloid that binds to zinc. Their approach, based on nuclear magnetic resonance (NMR), could also be used to reveal the structures of additional metal-bound amyloids.

“Even though there has been a lot of high-resolution, atomic level structural work on amyloids by solid-state NMR, people have really not studied the metal-binding aspects,” says Mei Hong, an MIT professor of chemistry and one of the senior authors of the paper, which appears in the Proceedings of the National Academy of Sciences the week of May 29. 

Researchers at UCSF and Syracuse designed the amyloid protein to catalyze a specific reaction: combining carbon dioxide and water to form bicarbonate. The newly discovered structure of the amyloid sheds light on how the protein performs this function and how zinc assists in the reaction catalysis.

William DeGrado, a professor of pharmaceutical chemistry at UCSF, is the paper’s other senior author. MT graduate student Myungwoon Lee is the lead author of the paper.

Structure determination

While amyloids are often associated with diseases such as Alzheimer’s and Parkinson’s diseases, other amyloids have normal biological functions.

The UCSF and Syracuse researchers first reported their artificial amyloid in 2014. Their goal was to produce a very simple metal-bound protein that could catalyze a chemical reaction necessary for life, in hopes of demonstrating that such simple metal-bound peptides could have been precursors to modern-day enzymes. In that paper, they showed that the peptide, which consists of seven amino acids bound to a zinc ion, could catalyze the conversion of carbon dioxide and water to bicarbonate as efficiently as the enzyme carbonic anhydrase, which performs this reaction in living cells and also requires zinc.

“It is plausible for very small peptides that bear metal ions to do chemistry, and the evolution of enzyme activities may have started from these small peptides,” Hong says.

The UCSF researchers designed their peptide so that its active site, where the chemical reaction takes place, would mimic that of carbonic anhydrase, which has a zinc ion tethered to three chains of the amino acid histidine. However, they didn’t know the precise structure of the fibrils formed by their peptide, which is where Hong and her MIT colleagues came in.

To determine the structure, the research team used a two-pronged approach based on NMR spectroscopy and bioinformatics, which is a method of using computer algorithms to analyze biological data.

Using NMR, the researchers first determined that the peptides form a long fibril chain that consists of layers of structures called beta sheets. Within each beta sheet, each peptide strand has two histidines that can interact with the next strand. Their next goal was to determine how the zinc ions fit into this multistranded and multilayered structure.

NMR uses the magnetic properties of atomic nuclei to reveal the structures of the molecules containing those nuclei. In this case, the researchers used NMR to analyze signals from key nitrogen atoms in the histidine sidechains that interact with zinc ions. By comparing these signals when the amyloids were and weren’t bound to zinc, the researchers determined that half of the histidines coordinate one zinc atom each, while the other half interact with two zinc atoms each. “The high concentration of histidines bridging two zinc ions is very unusual,” Hong says.

The researchers also used NMR to measure the angles of the bonds that allow histidine to interact with zinc, and then used bioinformatics to determine the possible structures consistent with those configurations. This revealed that one zinc atom sits between two amyloid-beta strands, and it is bound to one histidine sidechain from above and two from below. This forms a tetrahedral structure in which three histidine nitrogens hold the zinc in place while one histidine nitrogen remains unattached.

Early catalysis

The unattached histidine nitrogen is free to bind to a molecule of water, which is necessary to carry out the reaction catalyzed by the zinc ion. Hong’s collaborators at UCSF have previously shown that this amyloid catalyzes bicarbonate formation at a rate similar to that of carbonic anhydrase, supporting the theory that this type of simple amyloid could have been used by early life forms to carry out important reactions.

Hong now plans to begin studying the structure of metal-bound amyloids involved in neurodegenerative diseases. The amyloids involved in both Parkinson’s and Alzheimer’s diseases have been shown to bind to metal ions, including zinc and copper, but how these metals influence the diseases is not known, nor have their structures been determined.

“There have been some molecular dynamics simulations to guess how metals bind these histidines, but there has been no high-resolution, atomic-level investigation of the coordination structure,” Hong says.

The research was funded by the National Institutes of Health.

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Sustainability Connect 2017 brings MIT together to balance needs of the present and future

MIT faculty, staff, and students came together to celebrate the progress of the Institute’s campus sustainability efforts and to put their heads together to brainstorm ways MIT's unique culture of innovation can be further leveraged to test new ideas.

The diverse group gathered on May 8 for Sustainability Connect 2017, the third iteration of the annual conference sponsored by MIT’s Office of Sustainability (MITOS).

Over the past several years, MIT has used its power both as a research institution and living lab to tackle the issue of global climate change. In October 2015, MIT released a five-year Plan for Action on Climate Change, setting goals like reducing campus emissions by at least 32 percent by 2030. In November 2015, the MIT Campus Sustainability Working Groups released their collective recommendations for advancing sustainable design and construction, materials management, and green labs across campus.

“Two years ago, when we launched this event, we challenged ourselves to determine how MIT can be a game-changing force for sustainability in the 21st century,” MITOS director Julie Newman said in her opening remarks. “And I’m pleased to report that in this short period of time we’re at a place where we can point to the transformative efforts that MIT has made.”

It has been a busy year for sustainability at MIT. Newman noted several recent developments including Access MIT, a commuter benefits program for employees to encourage the use of public transportation; Summit Farms, MIT’s landmark solar energy power-purchase agreement with area partners; and the launch of Energize MIT, a digital platform through which MIT faculty, students, and staff can access data about campus energy use.

Deputy Executive Vice President Tony Sharon invited the audience to see new opportunities arising from the work already being done in sustainability and to maintain the momentum.

“We can reinvent the ways we build our buildings and shape our open spaces, rethink the ways we provide energy to the campus, and with the new data analytics in place, we have many opportunities for analysis, critique, and learning,” Sharon said.

Seeking new opportunities was a major focus of Sustainability Connect 2017. It was reflected in the conference’s theme: “Cultivating the Test Bed: Harvesting a Better Future for All,” and through the day’s agenda of panels, presentations, and brainstorming sessions. Opportunities for innovative thinking explored incorporating social justice in future solutions, new intersections of innovation and campus sustainability, and new venues for faculty, students, and staff to use the campus as a living lab.

Keynote speaker Julian Agyeman, a professor of Urban and Environmental Policy and Planning at Tufts University, challenged the audience to incorporate social dimensions into their sustainability projects.

“It is very difficult to retrofit systems with equity and social justice once they are in place,” Agyeman said. “We need to think about these dimensions from the outset.”

Agyeman highlighted the unique opportunity of the MIT community to bring sustainable solutions to bear on cities with diverse populations like Boston and Cambridge, and called on the audience to prioritize both social justice and sustainability in their work.

The morning sessions served as a conversation forum for students, staff, and faculty directly involved with the task forces, committees, working groups, and research on sustainability at MIT.  

The opening panel — “Exploring the Intersections between Innovation and Campus Sustainability at MIT” — touched on Institute’s history of innovation and current steps being taken by the administration to use this foundation for the next generation of sustainability projects.

Panelist Jim May, a senior project manager in MIT Campus Planning, explained how MIT’s architecture and campus spaces have always been ahead of their time and have served as a blueprint for university campuses around the world.

“We know that our research, science, and innovation are reflected in our architecture, and that our campus embodies what it is we want to do,” May said.

He said MIT has been rehearsing for the next paradigm shift in sustainable buildings, and is ready to again lead university campuses in taking the next steps.

Following the panel, participants conducted a workshop to explore what kinds of sustainability goals MIT might set in the future, on topics ranging from resilient buildings to smarter food systems.

“We are looking forward to working with campus leaders and the MIT community in the coming years to frame and define what goals will enable MIT to be a leader and exemplar of campus sustainability,” Newman said.

MITOS opened the afternoon sessions of Sustainability Connect to the greater MIT community this year, inviting students, staff and faculty from across departments to join the conversation on transforming the campus into a test bed and living lab for sustainability.

“This is the ‘muddy boots’ portion of the day,” said Joe Higgins, director of infrastructure business operations in the Department of Facilities.

Higgins moderated the afternoon panel: “Cultivating the Test Bed: Constructing the Campus Lab,” which featured the work of four researchers testing out sustainability solutions on campus.

“We’ve got a lot of ladder-climbers, hands-on wrench-turners, chemical-mixing folks here,” Higgins said “And the campus as test bed is a linking of these researchers with the operations staff at MIT.”

Panelists included Rachel Perlman, a PhD student in Institute for Data, Systems, and Society and MITOS Fellow who spoke about MIT’s material flow, and Kripa Varanasi, an associate professor in the Department of Mechanical Engineering, who discussed water savings in cooling towers located at MIT’s Central Utilities Plant. Other panelists were Marius Peters, a research scientist in the MIT Photovoltaics Research Lab who spoke about testing solar cells on campus, and Pamela Greenley, an associate director of MIT’s Office of Environment, Health and Safety who explored efforts to develop a green certification process for campus labs.

The day’s final ideation workshop was facilitated by MITOS staff and Amanda Graham of the Environmental Solutions Initiative. Audience members worked together in small groups to match campus-based questions with opportunities for partnerships, experiential learning and new research.

“We know that every person who works, visits or studies at MIT, regardless of their role, might have a big idea to improve the sustainability of the campus,” said Paul J. Wolff III, living lab design and strategic engagement project manager at MITOS. “We want to capture these ideas – and where possible, connect them with the right partners, infuse them with robust research and test them right here on the MIT campus in an effort to maximize the outcomes.”

The interactive activities illustrated what makes living-lab-style sustainability research unique at MIT. They also provided participants with a roadmap for cultivating new ideas and strategic collaborations moving forward.

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Conch shells spill the secret to their toughness

The shells of marine organisms take a beating from impacts due to storms and tides, rocky shores, and sharp-toothed predators. But as recent research has demonstrated, one type of shell stands out above all the others in its toughness: the conch.

Now, researchers at MIT have explored the secrets behind these shells’ extraordinary impact resilience. And they’ve shown that this superior strength could be reproduced in engineered materials, potentially to provide the best-ever protective headgear and body armor.

The findings are reported in the journal Advanced Materials, in a paper by MIT graduate student Grace Gu, postdoc Mahdi Takaffoli, and McAfee Professor of Engineering Markus Buehler.

Conch shells “have this really unique architecture,” Gu explains. The structure makes the material 10 times tougher than nacre, commonly known as mother of pearl. This toughness, or resistance to fractures, comes from a unique configuration based on three different levels of hierarchy in the material’s internal structure.

The three-tiered structure makes it very hard for any tiny cracks to spread and enlarge, Gu says. The material has a “zigzag matrix, so the crack has to go through a kind of a maze” in order to spread, she says.

Until recently, even after the structure of the conch shell was understood, “you couldn’t replicate it that well. But now, our lab has developed 3-D printing technology that allows us to duplicate that structure and be able to test it,” says Buehler, who is the head of the Department of Civil and Environmental Engineering.

Part of the innovation involved in this project was the team’s ability to both simulate the material’s behavior and analyze its actual performance under realistic conditions. “In the past, a lot of testing [of protective materials] was static testing,” Gu explains. “But a lot of applications for military uses or sports involve highly dynamic loading,” which requires a detailed examination of how an impact’s effects spread out over time.

For this work, the researchers did tests in a drop tower that enabled them to observe exactly how cracks appeared and spread — or didn’t spread — in the first instants after an impact. “There was amazing agreement between the model and the experiments,” Buehler says.

That’s partly because the team was able to 3-D print composite materials with precisely controlled structures, rather than using samples of real shells, which can have unpredictable variations that can complicate the analysis. By printing the samples, “we can use exactly the same geometry” as used in the computer simulations, “and we get very good agreement.” Now, in continuing the work, they can focus on making slight variations “as a basis for future optimization,” Buehler says.

To test the relative importance of the three levels of structure, the team tried making variations of the material with different levels of hierarchy. Higher levels of hierarchy are introduced by incorporating smaller length-scale features into the composite, as in an actual conch shell. Sure enough, lower-level structures proved to be significantly weaker than the highest level pursued in this study, which consisted of the cross-lamellar features inherent in natural conch shells.

Testing proved that the geometry with the conch-like, criss-crossed features was 85 percent better at preventing crack propagation than the strongest base material, and 70 percent better than a traditional fiber composite arrangement, Gu says.

Protective helmets and other impact-resistant gear require a key combination of both strength and toughness, Buehler explains. Strength refers to a material’s ability to resist damage, which steel does well, for example. Toughness, on the other hand, refers to a material’s ability to dissipate energy, as rubber does. Traditional helmets use a metal shell for strength and a flexible liner for both comfort and energy dissipation. But in the new composite material, this combination of qualities is distributed through the whole material.

“This has stiffness, like glass or ceramics,” Buehler says, but it lacks the brittleness of those materials, thanks to the integration of materials with different degrees of strength and flexibility within the composite structure. Like plywood, the composite is made up of layers whose “grain,” or the internal alignment of its materials, is oriented differently from one layer to the next.

Because of the use of 3-D printing technology, this system would make it possible to produce individualized helmets or other body armor. Each helmet, for example, could be “tailored and personalized; the computer would optimize it for you, based on a scan of your skull, and the helmet would be printed just for you,” Gu says.

These researchers “ingeniously used 3-D printing and experimentation to elucidate the effect of material hierarchy on bioinspired composites,” says Horacio Espinosa, a professor of mechanical engineering and director of the Theoretical and Applied Mechanics program at Northwestern University, who was not involved in this work. “An interesting remaining question,” he says, “is the applicability of the conch shell design to curved surfaces like those one would encounter in helmets.”

The research was supported by the Office of Naval Research, a National Defense Science and Engineering Graduate Fellowship, the Defense University Research Instrumentation Program (DURIP), the Institute for Soldier Nanotechnologies (ISN), and the Natural Sciences and Engineering Research Council of Canada.

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