The external advisory board dinner will be held on October 9, 2019. Immediately following the Materials Day Poster Session.
Location: MIT Student Center, West Lounge
Cocktails will start at 6:30pm.
The advisory board meeting will be held on October 10, 2019.
Location: Bush Room, Building 10-105
8:30am - 4:30pm
Machine Learning in Materials Research
MATERIALS DAY AGENDA
October 9, 2019
MIT, Kresge Theatre (W16)
Kresge Lobby, MIT Bldg. W16
||Welcome and Overview
Professor Carl V. Thompson
Director, Materials Research Laboratory, MIT
Accelerating Materials Design and Discovery for Electric Vehicles
Dr. Brian Storey
Director, Accelerated Materials Design & Discovery, TOYOTA Research Institute
||Text and Data Mining for Material Synthesis
Associate Professor Elsa Olivetti
Department of Materials Science & Engineering, MIT
Advancing Chemical Development Through Process Intensification, Automation, and Machine Learning
|11:00-12:00pm||Poster Previews: 2-minute talks by selected poster presenters|
Stratton Student Center, 3rd Floor
Twenty Chimneys/Mezzanine Lounge (Building W20)
|Computing at MIT
Professor Asu Ozdaglar
Department Head, Electrical Engineering & Computer Science, MIT
||Machine Learning in Optics: From Spectrum Reconstruction to Metasurface Design
Associate Professor Juejun (JJ) Hu
Department of Materials Science & Engineering, MIT
||Elastic Strain Engineering for Unprecedented Properties
Professor Ju Li
Departments of Nuclear Science & Eng. and Materials Science & Engineering, MIT
Learning matter: Materials Design Through Atomistic Simulations and Machine Learning
||Session Wrap Up
Professor Carl V. Thompson
Director, Materials Research Laboratory, MIT
||Poster Session and Social
La Sala de Puerto Rico, 2nd Floor
Stratton Student Center (Building W20)
MRL summer interns tackle materials science challenges, contributing to MIT faculty research labs, overcoming obstacles and gaining new skills.
MIT Materials Research Laboratory interns this summer covered a wide gamut of challenges working with materials as soft as silk to as hard as iron and at temperatures from as low as that of liquid helium [minus 452.47 F] to as high as that of melted copper [1,984 F].
Summer Scholars and other interns participated on the MIT campus in Cambridge, Mass., through the MIT MRL’s Materials Research Science and Engineering Center, with support from the National Science Foundation, AIM Photonics Academy, MRL Collegium, and the Guided Academic Industry Network [GAIN] program.
Simon Egner, from the University of Illinois at Urbana-Champaign, made samples of lead tin telluride to detect mid-infrared light at wavelengths from 4 to 7 microns for integrated photonic applications. Working with Materials Science and Engineering graduate student Peter Su, Egner measured several materials properties of the samples, including the concentration and mobility of electrons. “One thing we have come up with recently is adding lead oxide to try to decrease the amount of noise we get when sensing light with our detectors,” Egner says.
Lead tin telluride is an alloy of lead telluride and tin telluride, Su explains in the lab of MIT Materials Research Laboratory Principal Research Scientist Anuradha Agarwal. “If you have a lot of carriers already present in your material, you get a lot of extra noise, a lot of background signal, above which it’s really hard to detect the new carriers generated by the light striking your material,” Su says. “We’re trying to lower that noise level by lowering the carrier concentration and we’re trying to do that by adding lead oxide to that alloy.”
Juan Hincapie, from Roxbury Community College, took current and voltage measurements of samples in the lab of Riccardo Comin, assistant professor of physics. Wendy Moy, Physical Science teacher at Diamond Middle School in Lexington, Mass., also interned in the Comin lab, growing crystals. Comin’s lab studies superconductors as well as more traditional insulating and metallic semiconductor materials.
“In order to study their properties, we need to measure their electrical transport properties, which in simple terms, means their resistance, or if you like, resistivity, which is an intrinsic version of the resistance, and in order to do that we need to do measurement in a special geometry where we place four contacts on these samples and then we source and sample the current and the voltage,” Comin explains. The tests are conducted using a cryostat at extremely cold temperatures down to a temperature of about 4 kelvins [roughly the temperature of liquid helium]. These current and voltage measurements reveal the resistivity of the material.
“We need to place the samples in an environment whose temperature we can control from very low temperatures, say a few kelvins, up to room temperature and above,” Comin explains. “And then we want to track the resistance as it changes as a function of temperature and we want to see at which point it drops to zero, because that’s the defining feature of a superconductor. It has zero resistance.”
Hincapie says his summer internship was his first research experience and he learned how to program in Python and how to operate equipment in the lab. He hopes to attend a four-year college this fall to study civil engineering.
|Video: Creating Thin Films with Non-Linear Optical Properties|
Thin films for photonics
Summer Scholar Alvin Chang, from Oregon State University, created chalcogenide thin films with non-linear properties for photonics applications. He worked with Postdoctoral Fellow Samuel Serna in the lab of Associate Professor of Materials Science and Engineering Juejun (JJ) Hu. Chang varied the thickness of two different compositions, creating a gradient, or ratio, between the two across the length of the film. “We have two different materials. One is GSS, or germanium antimony and then sulfur, and the other is GSSE, which is germanium, antimony and then selenium,” Chang explains.
“The GSS and GSSE both have different advantages and disadvantages. We're hoping that by merging the two together in a film we can sort of optimize both their advantages and disadvantages so that they would be complementary with each other.” These materials, known as chalcogenide glasses, can be used for infrared sensing and imaging.
Superconducting thin films
Elizabeth [Lily] Hallett, from the University of Arkansas-Fayetteville, made 60 samples of molybdenum nitride thin films on different substrates [silicon oxide, magnesium oxide, silicon] and studied their electrical and superconducting properties in Professor of Electrical Engineering Karl K. Berggren’s lab. She examined the films in a four-probe instrument that measures electrical resistance and in a closed-cycle cryostat that measures the critical temperature. The hope is to develop single photon detectors based on the superconducting property of this material. Molybdenum nitride is predicted to transition to a superconducting state at a higher temperature than similar materials. “This is desirable because it takes less energy to cool the device down to its operating temperature,” Hallett says.
“I’ve been working to optimize deposition conditions for molybdenum nitride in the sputtering system in our lab, by varying all the parameters like temperature, pressure, substrate, gas flow and discharge currents,” she says. A thinner sample looks different from thicker samples with their mirror-like surface, she points out. “Thin films are essential for nanowire single photon detectors, so I have been working on increasing the critical temperature of films that are essentially 5 nanometers thick,” Hallett says.
“Something that I’ve learned that is extremely important is to do a lot of background reading on your project,” Hallett notes. “I tried to find every paper I could on molybdenum nitride. I wanted to know who else had tried to make this material and what results they achieved. Learning how to organize and understand this information was important in making decisions about what experiments to perform.”
Quantum dots for solar
Quantum dots were the focus of summer research for Sarai Patterson from the University of Utah. She synthesized the perovskite quantum dots in the lab of William A. Tisdale, ARCO Career Development Professor of Chemical Engineering, then examined them under a transmission electron microscope [TEM] in MIT MRL MRSEC program’s shared facilities.
After placing a sample in the TEM, Patterson says, “This is one of the samples I made yesterday, and I’m looking to see if I have quantum dots or if I just made nanoplatelets. So far I don’t see anything that looks very much like quantum dots. But we’ll see.”
“The beam is such high energy that a lot of the time it will start burning the sample before you can get a really good image of it and then that just degrades the focus and the image. So it’s kind of difficult,” Patterson says of the TEM work. Quantum dots can be used in LEDs and liquid crystal displays such as in TVs and cell phones. “The perovskite quantum dots that I’m working with have shown a lot of promise for solar technology which is primarily why I’m interested in quantum dots,” Patterson says.
In the Tisdale Lab, she varied the amount of each chemical ingredient to determine the best combination of materials. The quantum dots glow under ultraviolet light, a greenish color in the case of Patterson’s perovskite materials.
Protecting lasers from back splash
Brown University rising senior Ekaterina [Stella] Tsotsos studied cerium-doped iron garnet thin films in the lab of Caroline A. Ross, Toyota Professor of Materials Science and Engineering and Associate Head of the Department of Materials Science and Engineering. “These films are around 100 nanometers thick and they are 10 millimeters by 10 millimeters square. We’re testing their magnetic properties and their optical properties. The machine we’re using right now is called a VSM [vibrating sample magnetometer] and it vibrates the sample and magnetizes it and because it’s vibrating, it generates a current and you measure the current to see how much you can magnetize the sample,” Tsotsos says. “The value you’re measuring is how much can I magnetize this material by putting a magnetic field on it. My specific experiments are about temperature dependent measurements.”
The Ross lab is developing materials that can be used in photonic devices as isolators that protect the laser from any back reflection. “So light can go through forward but can’t come back and hit the laser, which would break it,” Tsotsos says.
Tsotsos worked with Materials Science and Engineering graduate student Takian Fakhrul. Besides magnetic measurements Tsotsos also did optical measurements of her garnet samples. Condensation at low temperatures became a challenge, she explains. “Once we get down to negative 60 degrees C, condensation starts forming on the film and it alters the light that we are trying to pass through it, so we get bad measurements then. But we’ve been working through it, heating it up first to try to dry it out, shooting a bunch of nitrogen through the stage, to try to make sure there is not water vapor in there. Yea, we’re trying to see what will work.”
Strengthening aerospace composites
Abigail Nason, from the University of Florida, studied the potential benefits of incorporating carbon nanotubes into carbon fiber reinforced plastic [CFRP] via a process termed “nanostitching” in the lab of Brian L. Wardle, Professor of Aeronautics and Astronautics. Bundles of carbon microfibers are known as tows and are used to make sheets of aerospace-grade carbon fiber reinforced plastic. Working with graduate student Reed Kopp, Nason took 3D scans of composite laminate samples to reveal their structure. “We’re working with 10 millimeter by 4 millimeter by 2 millimeter little rectangular composites and some of them have nano-stitch[ing] in them and some of them do not,” Nason explains.
Areas between sheets of the laminate are called the interlaminar region, and are weaker because they lack the added strength from mechanical reinforcement that fibers provide. Traditional composites have no reinforcement in this interlaminar region, and carbon nanotubes provide nano-scale fiber reinforcement in the nano-stitch version. Kopp notes that despite the high level of resolution required to elucidate an intricate architecture of micro-scale features, the 3D scans can’t distinguish the carbon nanotubes from the epoxy resin because they have similar density and elemental composition. “Since they absorb X-rays similarly, we can’t actually detect X-ray interaction differences that would indicate the locations of reinforcing carbon nanotube forests, but we can visualize how they affect the shape of the interlaminar region, such as how they may push fibers apart and change the shape of inherent resin-rich regions caused during carbon fiber reinforced plastic layer manufacturing.”
Nason adds that “It’s really interesting to see that there isn’t a lot of information out there about how composites fail and why they fail the way they do. But it’s really cool and interesting to be at the forefront of seeing this new technology and being able to look so closely at the composite layers and quantifying critical micro-scale material features that influence failure.”
Astatke Assaminew, a biotechnology student at Roxbury Community College, and Heather Giblin, a biology teacher at Brookline High School, interned in the lab of Katharina Ribbeck, associate professor of biological engineering.
Working with Postdocs Miri Krupkin and Gerardo Cárcamo-Oyarce and Research Scientist Bradley Turner, Assaminew investigated the effects of purified mucin polymers on the opportunistic bacterial pathogen, Pseudomonas aeruginosa, using live confocal microscopy. Giblin, who worked with biology graduate student Julie Takagi, investigated the effects of mucin polymers purified from saliva on biofilm formation in the opportunistic fungal pathogen, Candida albicans. Assaminew and Giblin learned to purify mucin polymers from native mucus tissues using size exclusion chromatography.
Both Roxbury Community College Chemistry and Biotechnology Professor Kimberly Stieglitz and Roxbury Community College student Credoritch Joseph worked in the lab of Assistant Professor in Materials Science and Engineering Robert J. Macfarlane. The Macfarlane Lab grafts DNA to nanoparticles, which enables precise control over self-assembly of molecular structures. The lab also is creating a new class of chemical building blocks that it calls Nanocomposite Tectons, or NCTs, which present new opportunities for self-assembly of composite materials.
Joseph learned the multi-step process of creating self-assembled DNA-nanoparticle aggregates, and used the ones he prepared to study the stability of the aggregates when exposed to different chemicals. Additionally, Joseph began to optimize a silica-embedding procedure for removing DNA-nanoparticle crystals from solution. Stieglitz created NCTs consisting of clusters of gold nanoparticles with attached polymers and examined their melting behavior in polymer solutions. She learned a multi-step process to produce NCTs, including how to spin the compounds in vials of water-based liquid, containing either DAP [diaminopyridine] or Thymine, each of which has hydrogen donor/acceptor pairs. After the spinning step, water and dimethylformamide [DMF] are removed, and the nanoparticles are re-suspended in toluene before being combined to assemble into NCTs. “They’re actually nanoparticles that are linked together through hydrogen bonding networks,” Stieglitz explains, “and the nanoparticles have gold which reacts with the S-H [sulfur-hydrogen end].”
Spinning particles with magnetism
Summer Scholar Ryan Tollefsen from Oregon State University joined Associate Professor of Materials Science and Engineering Alfredo Alexander-Katz’s lab to explore the dynamics of neutral colloidal particles spinning in a magnetic field. These simulations model generic neutral beads but show behavior similar to living cells, such as bacteria. “The goal with the spinners is to achieve self-assembly, which is when the active particles just by themselves create a structure,” Tollefsen says.
Tollefsen learned to write simulations in the Fortran programming language, adapting a freely available code for dissipative particle dynamics simulation known as CAMUS. “Before this summer, I had never created a piece of software that had more than probably 200 lines of code,” Tollefsen says. “Now I’m working with software that has over 4,000 lines of code. So one of the biggest skills I’ve learned is just keeping track of something that has so many moving parts.”
Applying a magnetic field that repeatedly crosses back and forth from positive to negative, Tollefsen says, causes the spinners first to spin in one direction, then to slow down and stop, and lastly to spin in the other direction. “When the spinners are kind of spinning like this, they form these little clusters but they don’t completely phase separate. They form little groups and then start to push other little groups away, and so you get kind of these clusters which are neatly organized with each other and that’s called a microphase separation,” Tollefsen explains.
“When we learn the rules of these systems, we start to get the idea of how we can use it to engineer synthetic living systems. I think when that technology is fully realized, it will define its era,” he says. “We kind of have living buildings where they’ll read the temperature and they’ll open and close windows automatically but imagine if you could have that kind of responsiveness and functionality within a material, microscopically. That’s the goal in my mind, when I study these spinners,” he says.
Activating silk fibers
Summer Scholar Sabrina Shen, from Johns Hopkins University, carried out molecular dynamics simulations of how different forms of carbon affect silk in the lab of Civil and Environmental Engineering Department Head Markus J. Buehler. “If we can put activated carbon inside silk and make conductive membranes with it, then it can be conductive, and then it can be used for flexible electronics or sensors,” Shen explains. The lab is interested in obtaining activated carbon from biomass, she says. Compared to pure carbon materials, like graphite or carbon nanotubes, biomass-derived activated carbons often contain oxygen and nitrogen, and this affects their interaction with silk proteins. “Previous studies have shown that graphene can disrupt hydrogen bonding within the silk beta crystals, which would decrease the mechanical strength of the silk. Now we want to see how biomass-derived carbons populated with different functional groups including both oxygens and nitrogens will interact with the silk, and how this affects the mechanical properties,” Shen says.
“I’ve never done computational research before so all of it is fairly new to me,” Shen says. “I was fairly set on graduate school before coming here, but I’m even more certain now, especially after I’ve had opportunities to talk to the other graduate students in my lab and to hear about their experiences.”
While she previously worked with biomaterials for the medical field, Shen says she finds the Buehler lab’s focus on bio-inspired materials and hierarchical design to be fascinating. “I like it a lot, and it’s definitely something I would consider for graduate research,” Shen says.
Analyzing cobalt supply and demand
Working in the research group of Elsa A. Olivetti, Atlantic Richfield Associate Professor of Energy Studies, Summer Scholar Danielle Beatty from the University of Utah, says she experienced an entirely different side of materials science and engineering from the experimental work she previously did.
Beatty developed scenarios to analyze the balance between supply and demand for cobalt, particularly in the face of increasing demand for lithium ion batteries in electric vehicles. “We’re focusing on how demand is going to change out to 2030,” Beatty explains. “We’re doing a short-term analysis, how demand is going to change, how supply of cobalt coming from both primary sources and recycling may have an impact on that demand-supply ratio.”
Beatty learned new coding skills in Python and gained a broader perspective on materials availability. “It’s opened up a whole new side of things for me. I never had really considered the computational side of materials science much, but coming into this, that’s definitely a possibility for me now and something I’d be really interested in pursuing further or at least incorporating more into my experimental work as well,” she says.
Creating neuro fibers
Bunker Hill Community College student Minhua Mei worked with Postdoc Mehmet Kanik in the lab of Associate Professor in Materials Science and Engineering Polina Anikeeva on a project to develop a flexible fiber probe. The goal is develop a neuro probe for recording brain activity in mice as part of an autism study. Mei worked with the polymer PMMA to create blocks about 10 inches long with electrodes melded into them that can be drawn out to a hundred times their length in a fiber drawing tower.
Improving flow batteries
Summer Scholar Julianna La Lane from the University of Puerto Rico at Mayagüez and Bunker Hill Community College student Zhirong [Justin] Fan worked on aqueous flow batteries in the lab of Fikile R. Brushett, the Cecil and Ida Green Career Development Chair, Associate Professor of Chemical Engineering.
Fan used electrochemical diagnostics to compare the microstructure and the performance of different commercial electrodes in flow batteries. La Lane created hierarchically porous electrodes derived from polyacrylonitrile, optimizing the fabrication procedure to tune properties including porosity, hydrophilicity [ease of wetting by water], and electrical conductivity. “We’re trying to make it as porous as possible,” La Lane explains.
Synthesizing electronic materials
Summer Scholar Michael Molinski, from the University of Rhode Island, and Roxbury Community College student Bruce Quinn worked in the lab of Assistant Professor of Materials Science and Engineering Rafael Jaramillo. Working with graduate students Stephen Filippone and Kevin Ye, both Molinski and Quinn made solid materials, producing powders of compounds such as barium zirconium sulfide, which are desirable for their optical and electrical properties.
The process involves mixing together the chemical ingredients to produce the powders in a quartz tube in the absence of air and sealing it. “In the reaction, you don’t want any oxygen to create an oxide, so he seals them in the tube, then he puts them in the furnace, heats them up and hopefully creates barium zirconium sulfide when it comes out,” Filippone explains.
The first GAIN program participant, Quinn hot pressed the powders into pellets. He expects to complete an associate degree in biotechnology next spring. Molinski also grew crystals. Both examined their powders with X-Ray diffraction.
Developing multiple sclerosis models
Summer Scholar Fernando Nieves Muñoz, from the University of Puerto Rico, Mayagüez, worked in the lab of Krystyn Van Vliet, the Michael (1949) and Sonja Koerner Professor of Materials Science and Engineering, to develop mechanical models of multiple sclerosis [MS] lesions. Nieves Muñoz worked closely with Research Scientist Anna Jagielska and chemical engineering graduate student Daniela Espinosa-Hoyos. “We are trying to find a way to stimulate repair of myelin in MS patients so that neurological function can be restored. To better understand how remyelination works, we are developing polymer-based materials to engineer models of MS lesions that mimic mechanical stiffness of real lesions in the brain,” Jagielska explains.
Nieves Muñoz used stereolithography 3D printing to create cross-linked polymers with varying degrees of mechanical stiffness and conducted atomic force microscopy studies to determine the stiffness of his samples. “Fernando has been optimizing a commercial 3D printer to generate stiffness maps by changing the gray scale values of digital masks and in this way change the extent of cross-linking of the polymer within a given model,” Espinosa-Hoyos says.
“Our long-term goal is to use these models of lesions and brain tissue to develop drugs that can stimulate myelin repair,” Nieves Muñoz says. “As a mechanical engineering major, it has been exciting to work and learn from people with diverse backgrounds.”
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The prestigious awards are supporting five innovative projects that challenge established norms and have the potential to be world-changing.
Eight MIT faculty members have been awarded one of the Institute’s most respected honors: the Professor Amar G. Bose Research Grant, which supports work that is unorthodox, and potentially world-changing. The topics of the grants range from nanoscale textiles that purify drinking water, to revolutionary new approaches in catalysis, high-speed logic, and drug delivery.
The awards are named for the late Amar G. Bose ’51, SM ’52, ScD ’56, a longtime MIT faculty member and the founder of the Bose Corporation. The Bose Research Fellows for 2018 are Dirk Englund, Laura L. Kiessling, Leonid S. Levitov, Nuno F. Loureiro, Elizabeth M. Nolan, Julia Ortony, Katharina Ribbeck, and Yuriy Román. Each of this year’s grants reflects the innovative thinking, intellectually adventurous spirit, curiosity, and enthusiasm that characterize the Bose grant program. They also embody the value and practice of interdisciplinary collaboration at MIT, which drives discovery and expands the intellectual horizons of individual researchers, their colleagues, and their students.
View the embedded image gallery online at:
An awards ceremony was hosted by MIT President L. Rafael Reif, and the awards were presented by MIT Provost Martin Schmidt, the Ray and Maria Stata Professor of Electrical Engineering and Computer Science. The fellows provided updates on their ongoing work at the ceremony.
As President Reif noted in his remarks, the 2018 awards carry special meaning, because they are the first to be awarded since the untimely passing in November of Vanu Gopal Bose ’87, SM ’94, PhD ’99, the son of Amar Bose and a member of the MIT Corporation. In his professional life and his service to MIT, Vanu Bose was a champion of innovation and supported many others in their pursuit of knowledge and discovery.
Novel electronic fluids for high-speed logic in quantum materials
Three investigators from the fields of quantum physics, quantum mechanics, and nuclear science and engineering will pool their expertise to explore the wonder material known as graphene. Graphene is an atomically thin carbon sheet possessing unique properties that have made it the subject of intense interest, particularly for its applications in electronics. One of those properties, says Leonid Levitov, professor of physics, is the behavior of electrons in graphene, which travel through this material “like free particles, along straight lines, ballistically, over enormous distances, and showing robust quantum-mechanical behavior up to room temperature.”
Dirk Englund, associate professor of electrical engineering and computer science, believes that insights gained from their study of graphene may advance the creation of a new logic device, capable of performing logic operations “many orders of magnitude faster and with much lower energy consumption” than the logic devices powering today’s electronics.
“Moore’s Law is coming to an end and really new concepts are needed [to] go beyond the traditional computer architecture,” Englund notes. “A lot of incremental paths have been explored already and they haven’t given us ... another few orders of magnitude of performance. We have to look at radically new ideas.”
Nuno Loureiro, associate professor of nuclear science and engineering, describes his role in the project as providing “a bridge between plasma physics” — his own area of expertise — “and the fluid-like dynamics of electrons in graphene.” In his discussions with Levitov, he has come to believe that “there are methods and ideas that can be ported from one system to the other.”
“That would be a wonderful outcome” says Loureiro, particularly for exploring some of the astrophysical applications of plasma research. “It’s possible that the behavior of a graphene sheet can map directly to a pair plasma, and if we know how to read that map, we [might create] the first quote-unquote pair plasma in the lab.” He credits the Bose grant for giving him a chance to pursue this unorthodox idea, and stretch beyond his own research.
“I’m reaching to something that is completely outside of my domain of expertise, and I’m going to learn a lot. I’m hoping those ideas can then be inspiring for things in my specific domain.”
Levitov also appreciates the exchange of ideas that the project will yield.
“To a theorist, this is all particularly appealing, as it provides a unique perspective on the developments in my field by connecting it to other fields and, of course, because of a possibly far-reaching outcome this collaboration can lead to.”
Controlling infections using nature’s strategies
Our bodies are home to trillions of microbes, the vast majority of which reside in the mucus that coats our respiratory tracts, digestive systems, and other bodily systems. Yet the exact functions and molecular structures of mucus remain largely a mystery. Laura Kiessling, professor of chemistry, and Katharina Ribbeck, the Hyman Career Development Professor in Biological Engineering, will use their Bose grant to explore how mucus protects against pathogens, and use that knowledge to create mimetic, bio-inspired materials.
Ribbeck compares mucus’s long, thread-like polymers to “tiny bottle brushes, and the bristles of these brushes are sugar molecules.” These glycoproteins regulate microbial physiology by suppressing harmful pathogens and supporting the body’s diverse microbiota. “It's hard to get down to a molecular-level understanding of how our bodies do that,” says Kiessling, but by fabricating bio-inspired materials, “we can alter their properties systematically, and ask those molecular questions that are much harder to investigate with natural materials.”
Ribbeck says her team will identify which glycoproteins have the most important effects. That knowledge then “will become the tools for [Kiessling], who will begin to build mimetic, synthetic versions of these molecular structures.” With the rise of antibiotic-resistant infections, they see enormous potential in disarming pathogens rather than killing them with antibiotics (thereby creating evolutionary pressure to become antibiotic-resistant). Instead, as Ribbeck puts it, they are “identifying nature’s strategies and then implementing them with creative chemistry.”
Kiessling and Ribbeck say that the Bose grant has enabled them to form a dynamic partnership, and pursue a high-risk, high-reward idea.
“As a scientist, you have your dreams, the stuff that keeps you awake at night,” says Ribbeck, and the research she will conduct with Bose grant support is one such project. “I am immensely grateful.” Kiessling is also excited to work on a project with broad applications: “If we can change how people think about treating infectious disease, and [move] toward exploiting natural mechanisms, that could be really transformative.”
A heavy-metal Trojan horse
One of the most serious threats to human health is the lack of new antibiotics and the rise of antibiotic-resistant disease. To tackle this problem, Elizabeth Nolan, an associate professor of chemistry, will use the Bose research grant to explore the design and delivery of nontraditional antibiotics using a Trojan horse strategy that takes advantage of the mechanisms used by bacteria to obtain iron.
“Our idea is that, since these bacteria are expressing machinery that enables iron acquisition, maybe we can take advantage of that machinery as a way to target and deliver antibacterial or toxic cargo, in a species- or strain-selective manner.” The Bose grant will enable her to “build upon [previous work] and start delivering nontraditional toxic cargo into the cell, masked as a beneficial iron chelator to the bacteria.”
This precision targeting could minimize the toxicity of drugs to the host, while addressing the problem of antibiotic resistance. It’s the type of unconventional approach that Nolan says can be challenging to fund with traditional sources. Gathering enough preliminary data to support the feasibility of a high-risk idea can be especially challenging, she adds.
With the Bose grant, Nolan can take that step, creating avenues for future research in her own lab as well as “tremendous opportunity for collaboration” with researchers in other areas of inquiry. She uses the metaphor of a tree: “We need to build the trunk right now, by making the molecules, and then once we have those, we can branch off in many different directions.”
Nolan and her colleagues have been hoping to pursue these ideas for several years, and now, she says, “we can hit the ground running. I’m delighted and very grateful.”
Functional textiles for water purification
With the support of a Bose research grant, Julia Ortony, the Finmeccanica Career Development Professor of Engineering, hopes to create simple, yet powerful, nanoscale solutions to the problem of arsenic-contaminated drinking water, a threat to the health and lives of millions in Bangladesh and other parts of South Asia.
“In our lab, we design small molecules that spontaneously self-assemble in water,” says Ortony. Their goal is to match the mechanical properties of each nanostructure with particular applications. Arsenic removal requires “very high surface area to remove trace amounts of toxins, and very robust structures so that we have very little molecular exchange.”
Current methods for removing arsenic are bulky, costly, and hard to maintain. A fabric made of nanoscale fibers would provide the surface area necessary to remove arsenic and could be functionalized with a chemical to grab arsenic ions. It would be simple to distribute and use, and could even be recharged. “We could easily modify this material (to) remove lead or other metals,” she adds.
One inspiration behind Ortony’s proposal is a solution devised for guinea worm disease, a parasitic illness spread through drinking water. This disease was eradiated with an astoundingly simple solution: filtering drinking water through nylon fabric. Though contaminants like arsenic and lead are much more complicated to remove, Ortony believes a simple, cost-effective method utilizing nanoscale fabrics is within reach.
The Bose grant has allowed her to think more expansively about her research, created exciting opportunities for her students, and enabled her to pursue a project that engages multiple disciplines, including some that are completely new to her. “You learn a lot that way. You can bring very different ideas together, and I think that’s how a lot of discoveries and inventions are made,” she says.
Breaking away from mainstream catalysis
“The Bose grant is itself like a catalyst,” says Yuriy Román, associate professor of chemical engineering. Román’s research centers on heterogeneous catalysis, with the goal of making chemical reactions faster, more stable, and more efficient. With the support of the Bose research grant, he will embark on a new exploration: the potential of electric fields to impact molecular interactions on catalytic gas-solid surfaces.
“In our lab we work on developing strategies to enable renewable energy, implement renewable chemicals and to replace critical materials, but we have never engaged in this idea of joining the fields of electrochemistry and traditional high-temperature catalysis. It’s a completely new direction.”
The primary aims in catalysis, Román explains, are maximizing carbon economy, minimizing reactor downtime, and maximizing stability. The use of electric fields offers “an additional handle to control the catalytic process” with a high level of precision.
Román was pleased to find the very possibility he is exploring described in papers published in the 1970s by Constantinos G. Vayenas, a former professor of chemical engineering at MIT. By using today’s cutting-edge tools to examine the phenomena that Vayenas observed, Román and his team can expand Vayenas’s work, while adding new insights of their own.
While research into the unknown is a bit unnerving, Román says it also “reignites excitement” for discovery for everyone in the lab. He is grateful for the generosity of the Bose family and for the example of Professor Amar Bose, whose wide-ranging contributions and fearless spirit are inspiring. “I'm very happy that we might continue his legacy in some way.”
– Resource Development | MIT News
February 11, 2019
Jaramillo lab launches GAIN program to connect community college students to career opportunities in Boston and the region.
|MIT Assistant Professor of Materials Science and Engineering Rafael Jaramillo is rolling out the Guided Academic Industry Network (GAIN) program, which couples summer research on campus with a chance to work at a local company afterwards. Image, Denis Paiste, MIT MRL.|
Regional employers are coping with too few qualified candidates for materials science-related jobs, MIT Assistant Professor of Materials Science and Engineering Rafael Jaramillo says, but many community college students are unaware of the opportunities available to them. Jaramillo hopes to grow the pool of materials scientists beginning with one student at a time.
This June, Jaramillo’s lab is rolling out the Guided Academic Industry Network (GAIN) program, which will offer at least one intern for each of the next five summers a chance to conduct research in his lab, coupled with the possibility to intern at a local company the following summer.
Five companies have agreed to participate by interviewing the GAIN interns and possibly offering them a summer research internship. They are 1366 in Bedford, Ambri in Cambridge and Marlborough, Saint-Gobain in Northboro, Veloxint in Framingham, and Xtalic in Marlborough. “These companies were rather specifically selected for reliance on traditional materials science skills and materials processing skills,” Jaramillo says. All are within commuting distance of Boston.
“They will only take interns by mutual agreement. The company and the student have to be a match, but they’ve agreed in principle to reserve internship slots,” Jaramillo says. Both the research lab and company internships will last eight weeks.
Currently, Jaramillo says, the GAIN program is funded through his National Science Foundation CAREER award to host one new student per summer. He hopes to expand the program in the future through industrial sponsorship or renewed government funding.
Qualified candidates in materials science are needed for jobs at a variety of companies in ceramics, adhesives and coatings, lubricants and electronic materials, Jaramillo says.
|Noon Farsab, from Bunker Hill Community College, conducted research in MIT Assistant Professor of Materials Science and Engineering Rafael Jaramillo’s lab during the summer of 2017. Image courtesy of Rafael Jaramillo.|
Demand for materials scientists is expected to grow nationally by 7.1 percent over the decade ending in 2026, according to U.S. Department of Labor, Bureau of Labor Statistics [BLS] Employment Projections. Materials engineers are expected to grow at a slower rate, 1.6 percent. For May 2017, BLS estimated the number of materials scientists working in Boston at 140 and in Massachusetts at 440, with a larger number working as materials engineers, 320 in Boston and 650 in the state overall.
GAIN will target participants from Bunker Hill Community College and Roxbury Community College. The first student intern will be Bruce Quinn from Roxbury Community College. Interns will gain an introduction to materials science and hands-on experience with materials processing at MIT.
GAIN interns will tie in to the MIT Materials Research Laboratory’s National Science Foundation-funded Materials Research Science and Engineering Center [NSF-MRSEC] community college internship and Summer Scholars programs, giving them the opportunity to attend weekly luncheon meetings covering topics such as crafting a high-quality poster presentation, applying to graduate school, understanding patents and trademarks, and pursuing careers in materials science and other engineering fields.
Over the past two summers, Jaramillo hosted two students in his lab, Hlee Yang from Roxbury Community College, and Noon Farsab, from Bunker Hill Community College. Neither was familiar with materials science before being introduced to the Jaramillo lab. “I would say that it’s their level of willingness to try new things and the success that they had in my group was one factor that led to this program being started,” Jaramillo says. “They’ve done good work. Our research moves forward a little bit faster than if they weren’t here.”
The impact of outreach to community college students is multi-faceted. “As an educator, it feels really good to see the students succeed. These are students who we don’t get to interact with very often, and it’s been a real pleasure to see them learn something completely new and find success, so there is a satisfaction that comes from that,” he says. The summer internships also are a service to materials science.
“When you see the opportunity that these students present, and you see the need that the industry that we serve has, and you see an opportunity to help, it’s great that I have the opportunity to do it,” Jaramillo says.
|Hlee Yang, from Roxbury Community College, conducted research in MIT Assistant Professor of Materials Science and Engineering Rafael Jaramillo’s lab during the summer of 2016. Image, Denis Paiste, MIT MRL.|
Jaramillo’s interns will work on developing new electronic materials from special compounds known as complex chalcogenides. “The types of work they’ll be doing in my lab, which is bulk materials processing and phase identification, those are skills that will be directly useful for those companies,” he says. The students will produce new semiconductors using bulk techniques, such as mixing powders and synthesizing solid-state materials in quartz ampoules. “They get their hands on some fun equipment, they get to do some machining, they get to learn X-Ray diffraction, so really essential materials characterization techniques,” Jaramillo explains.
GAIN program participants must follow up their summer lab experience by presenting their MIT summer research results to fellow students back at their own campuses and similarly must also give a presentation after their second summer industry internship. Along the way they’ll be coached in soft skills such as resume and interview preparation.
There is no requirement that participants get a job or further their education in materials science. But, Jaramillo says, “We’ve gotten to expose the student to the field of materials, we’ve gotten to identify a potential new pipeline of employees for local companies, and I’ve gotten some great research done over the summer.”
Machine-learning system finds patterns in materials “recipes,” even when training data is lacking.
|A new machine-learning system for analyzing materials “recipes” uses a variational autoencoder, which squeezes data (left-hand circles) down into a more compact form (center circles) before attempting to re-expand it into its original form (right-hand circles). If the autoencoder is successfully trained, the compact representation will capture the data’s most salient characteristics. Image, Chelsea Turner, MIT|
Last month, three MIT materials scientists and their colleagues published a paper describing a new artificial-intelligence system that can pore through scientific papers and extract “recipes” for producing particular types of materials.
That work was envisioned as the first step toward a system that can originate recipes for materials that have been described only theoretically. Now, in a paper in the journal npj Computational Materials, the same three materials scientists, with a colleague in MIT’s Department of Electrical Engineering and Computer Science (EECS), take a further step in that direction, with a new artificial-intelligence system that can recognize higher-level patterns that are consistent across recipes.
For instance, the new system was able to identify correlations between “precursor” chemicals used in materials recipes and the crystal structures of the resulting products. The same correlations, it turned out, had been documented in the literature.
The system also relies on statistical methods that provide a natural mechanism for generating original recipes. In the paper, the researchers use this mechanism to suggest alternative recipes for known materials, and the suggestions accord well with real recipes.
The first author on the new paper is Edward Kim, a graduate student in materials science and engineering. The senior author is his advisor, Elsa Olivetti, the Atlantic Richfield Assistant Professor of Energy Studies in the Department of Materials Science and Engineering (DMSE). They’re joined by Kevin Huang, a postdoc in DMSE, and by Stefanie Jegelka, the X-Window Consortium Career Development Assistant Professor in EECS.
Sparse and scarce
Like many of the best-performing artificial-intelligence systems of the past 10 years, the MIT researchers’ new system is a so-called neural network, which learns to perform computational tasks by analyzing huge sets of training data. Traditionally, attempts to use neural networks to generate materials recipes have run up against two problems, which the researchers describe as sparsity and scarcity.
Any recipe for a material can be represented as a vector, which is essentially a long string of numbers. Each number represents a feature of the recipe, such as the concentration of a particular chemical, the solvent in which it’s dissolved, or the temperature at which a reaction takes place.
Since any given recipe will use only a few of the many chemicals and solvents described in the literature, most of those numbers will be zero. That’s what the researchers mean by “sparse.”
Similarly, to learn how modifying reaction parameters — such as chemical concentrations and temperatures — can affect final products, a system would ideally be trained on a huge number of examples in which those parameters are varied. But for some materials — particularly newer ones — the literature may contain only a few recipes. That’s scarcity.
“People think that with machine learning, you need a lot of data, and if it’s sparse, you need more data,” Kim says. “When you’re trying to focus on a very specific system, where you’re forced to use high-dimensional data but you don’t have a lot of it, can you still use these neural machine-learning techniques?”
Neural networks are typically arranged into layers, each consisting of thousands of simple processing units, or nodes. Each node is connected to several nodes in the layers above and below. Data is fed into the bottom layer, which manipulates it and passes it to the next layer, which manipulates it and passes it to the next, and so on. During training, the connections between nodes are constantly readjusted until the output of the final layer consistently approximates the result of some computation.
The problem with sparse, high-dimensional data is that for any given training example, most nodes in the bottom layer receive no data. It would take a prohibitively large training set to ensure that the network as a whole sees enough data to learn to make reliable generalizations.
The purpose of the MIT researchers’ network is to distill input vectors into much smaller vectors, all of whose numbers are meaningful for every input. To that end, the network has a middle layer with just a few nodes in it — only two, in some experiments.
The goal of training is simply to configure the network so that its output is as close as possible to its input. If training is successful, then the handful of nodes in the middle layer must somehow represent most of the information contained in the input vector, but in a much more compressed form. Such systems, in which the output attempts to match the input, are called “autoencoders.”
Autoencoding compensates for sparsity, but to handle scarcity, the researchers trained their network on not only recipes for producing particular materials, but also on recipes for producing very similar materials. They used three measures of similarity, one of which seeks to minimize the number of differences between materials — substituting, say, just one atom for another — while preserving crystal structure.
During training, the weight that the network gives example recipes varies according to their similarity scores.
Playing the odds
In fact, the researchers’ network is not just an autoencoder, but what’s called a variational autoencoder. That means that during training, the network is evaluated not only on how well its outputs match its inputs, but also on how well the values taken on by the middle layer accord with some statistical model — say, the familiar bell curve, or normal distribution. That is, across the whole training set, the values taken on by the middle layer should cluster around a central value and then taper off at a regular rate in all directions.
After training a variational autoencoder with a two-node middle layer on recipes for manganese dioxide and related compounds, the researchers constructed a two-dimensional map depicting the values that the two middle nodes took on for each example in the training set.
Remarkably, training examples that used the same precursor chemicals stuck to the same regions of the map, with sharp boundaries between regions. The same was true of training examples that yielded four of manganese dioxide’s common “polymorphs,” or crystal structures. And combining those two mappings indicated correlations between particular precursors and particular crystal structures.
“We thought it was cool that the regions were continuous,” Olivetti says, “because there’s no reason that that should necessarily be true.”
Variational autoencoding is also what enables the researchers’ system to generate new recipes. Because the values taken on by the middle layer adhere to a probability distribution, picking a value from that distribution at random is likely to yield a plausible recipe.
“This actually touches upon various topics that are currently of great interest in machine learning,” Jegelka says. “Learning with structured objects, allowing interpretability by and interaction with experts, and generating structured complex data — we integrate all of these.”
“‘Synthesizability’ is an example of a concept that is central to materials science yet lacks a good physics-based description,” says Bryce Meredig, founder and chief scientist at Citrine Informatics, a company that brings big-data and artificial-intelligence techniques to bear on materials science research. “As a result, computational screens for new materials have been hamstrung for many years by synthetic inaccessibility of the predicted materials. Olivetti and colleagues have taken a novel, data-driven approach to mapping materials syntheses and made an important contribution toward enabling us to computationally identify materials that not only have exciting properties but also can be made practically in the laboratory.”
The research was supported by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, the U.S. Office of Naval Research, the MIT Energy Initiative, and the U.S. Department of Energy’s Basic Energy Science Program.
Larry Hardesty | MIT News Office
December 21, 2017
MIT researchers demonstrate a new electrochemical method to study thermodynamic processes in an ultra-high temperature molten oxide
|Video of the operating cell shows oxygen bubbles forming within the cell as the alumina decomposes into pure aluminum at the cathode and pure oxygen at the iridium anode. Video, Bradley R. Nakanishi.|
The thermodynamic properties of compounds such as aluminum oxide, which are known as refractory materials because they melt at temperatures above 2,000 degrees Celsius [3,632°F], have been difficult to study because few vessels can withstand the heat to contain them and those that do often react with the melt, in effect contaminating the melt.
Now MIT researchers show a container-less electrochemical method to study the thermodynamic properties of these hot melts in a paper published in the Journal of The Electrochemical Society.
“We have a new technique which demonstrates that the rules of electrochemistry are followed for these refractory melts,” says senior author Antoine Allanore, Associate Professor of Metallurgy. “We have now evidence that these melts are very stable at high temperature, they have high conductivity.”
Adapting a thermal imaging (or arc imaging) furnace more commonly used for floating zone crystal growth, MIT graduate student Brad Nakanishi melted an alumina [aluminum oxide] rod and contacted the liquid pendant droplet that it formed with electrodes, creating an electrochemical cell that allowed decomposition of pure, alumina electrolyte to oxygen gas and aluminum alloy by electrolysis for the first time. The aluminum oxide itself serves as the electrolyte in this electrochemical cell, which operates similarly to water electrolysis.
“Decomposition voltage measurements give us direct access to the quintessential thermodynamic property that is chemical potential, also called Gibbs energy,” Nakanishi explains. “We’ve shown we make electrochemical measurements in a new class of electrolytes, the molten refractory oxides.” The change in this Gibbs energy, or chemical potential, with respect to temperature is known as entropy. “At high temperatures, entropy is really important and very challenging to predict, so having ability to measure entropy in these systems is key,” he says.
A hanging droplet
Using this technique, four reflected xenon lamps hone in on the tip of the sample, melting a liquid droplet, which is held to the rod by surface tension and quickly solidifies after the lights are turned off. While the droplet is liquefied, the electrodes are raised into the droplet to complete an electrical circuit, with the liquid alumina itself functioning as the electrolyte. “That’s something that we have not seen done otherwise, as well, doing electrochemistry in a suspended droplet above 2000°C,” Nakanishi says.
The hanging droplet has a high surface tension relative to its density. “The concentration of the light energy, hot zone, and large thermal gradients present, allows us in a very controlled way to create a situation for stable droplet and electrode contact,” Nakanishi says. “It sounds challenging, but the method we’ve refined is straightforward and rapid to operate in practice thanks, in part, to a camera enabling continuous observation of the droplet and electrodes during the experiment.”
The stability of the liquid aluminum oxide and a smart choice of electrode materials allow measurement of well-defined energy levels, Allanore says. “The paper shows that we can now measure fundamental thermodynamic properties of such a melt,” Allanore says. “In the case of molten alumina, we’ve actually been able to study the property of the cathode product. As we decompose aluminum oxide, to oxygen on one side [anode] and aluminum on the other side [cathode], then that liquid aluminum interacts with the electrode, which was iridium in that case,” Allanore says.
Video of the operating cell shows oxygen gas bubbles forming within the cell as the alumina decomposes into aluminum at the cathode [the negatively charged electrode] and pure oxygen at the iridium anode [the positively charged electrode]. The aluminum does interact with the iridium cathode, which is confirmed by partial melting and post-experiment images of the microstructure showing an aluminum-iridium alloy deposit.
“We can now calculate the thermodynamic property of that alloy, of that interaction, which is something that was never measured before. It was calculated and predicted. It was never measured. Here in this paper we confirm actually predictions from computation using our method,” Allanore says.
New predictive powers
For key industrial questions, such as how hot a turbine engine can run, engineers need thermodynamic data on both the solid and liquid states of metal alloys, in particular, the transition zone at which a solid melts. “We’re not so great on the liquid state, and at high temperature we also have a lot of trouble measuring Gibbs energy in the liquid state,” Nakanishi says.
“Here we’re adding experimental data,” he says. “We’ve created a method that you can measure the Gibbs free energy of a liquid, so now combined with our ability in a solid, we can start informing things like these transition temperatures among other thermodynamic questions, which are related to material stability.” The melt is ionic, containing a mix of both negatively charged oxygen anions and neutral oxygen atoms as well as positively charged aluminum cations and neutral aluminum atoms.
“The key significance of Bradley Nakanishi and Antoine Allanore’s research findings is the capability to determine thermodynamic parameters (e.g., thermodynamic activity) at temperatures greater than 1600°C from the electrochemical measurements for molten oxides, as well as the applicability to a broader electrolyte from a molten oxide to a molten salt,” says University of Texas at El Paso Professor of Mechanical Engineering Arturo Bronson, who was not involved in this research. “In addition, a possible relation of the oxygen partial pressure to the doubly-charged, free oxygen ion will characterize its effect on the associated cations and anions within the molten oxide to explain thermodynamic behavior between the liquid metal and liquid oxide.”
“The quality of the research is a world-class approach developed for difficult experimental studies of ultra-high temperature reactions of liquid metals and liquid oxides, especially with inclusion of electrochemical impedance spectroscopy,” Bronson says. However, a limitation of the study is the uncertainty of the temperature measurements within a range of plus or minus 10 degrees Celsius. “The uncertainty of the measured parameters will ultimately depend on the accuracy of the measured temperature (already at ± 10 kelvins), because the electrochemical parameters (i.e., voltage and current) will clearly depend on the temperature uncertainty,” Bronson explains.
More electrolyte possibilities
Electrochemistry is one of the most selective processing technologies, Allanore notes, “but to date it was very challenging to study the electrochemistry with these high temperature melts.” Electrolyte selection is key for designing new processes for the electrochemical extraction of reactive metals, and the new work demonstrates that more electrolytes are available for extracting metals. “We can now study the solubility of ores containing refractory metal oxides in these melts. So we are basically now adding at least 3 or 4 candidate electrolytes that could be used for metal extraction, in particular for what we call reactive metals such as aluminum, niobium, titanium, or the rare earths,” Allanore adds. This research was funded by the U.S. Office of Naval Research.
Future work will focus on applying these high-temperature electrochemical techniques to investigate the potential for selectively separating the rare earth oxides. Though required in only relatively small quantities usually, the individual rare earth elements are essential for high-tech applications, including cell phones and electric vehicles. Well-established methods to concentrate rare earth oxides from their ore produce a mixture of the 14 rare earth oxides, Allanore notes. “If we were using such a rare earth oxide mixture as our electrolyte, we could potentially selectively separate one rare earth metal from the 13 others,” he says.
New, stable materials such as rare earth oxides that can withstand high temperatures are needed for uses as varied as building faster airplanes and extending the lifetime of nuclear power plants. But one country, China, holds a near monopoly over rare earth element production. “The separation of rare earths from each other is the key challenge in making rare earth metals extraction more sustainable and economically feasible,” Nakanishi says.
While the newly published paper examines a single component electrolyte, aluminum oxide by itself, “Our aim is to extend this approach so that we can measure chemical potentials, Gibbs energy, in multi-component electrolytes,” Nakanishi explains. “This opens up the door to many more candidates for electrolytes that we can use to extract metals, and also make oxygen,” Nakanishi says. This ability to exhaust oxygen as a byproduct rather than carbon monoxide or carbon dioxide has potential to reduce greenhouse gas emissions and global warming.
– Denis Paiste, Materials Research Laboratory
Updated December 11, 2017
The Materials Research Laboratory (MRL) will celebrate renovations to the Electron Microscopy (EM) Shared Experimental Facility in Building 13 on Monday, Oct. 7, 2019, from 3:00 to 5:00 p.m. The event is open only to the MIT community.
|A specially designed transmission electron microscope in MIT Materials Research Laboratory’s newly renovated Electron Microscopy (EM) Shared Facility in Building 13. Photo, Denis Paiste, Materials Research Laboratory.|
The EM suite, which is part of the National Science Foundation-funded Materials Research Science and Engineering Center (MRSEC) within MRL, is now home to an ultra-high vacuum evaporator system and specially designed transmission electron microscope, which IBM donated to MIT. The equipment will be used by Frances M. Ross, the Ellen Swallow Richards Professor in Materials Science and Engineering, who joined the Department of Materials Science and Engineering (DMSE) faculty last year, moving from the Nanoscale Materials Analysis department at the IBM Thomas J. Watson Research Center.
Greene Construction completed the EM suite renovations, which included new flooring and lighting, a new entrance, repainting, and an updated meeting area with video presentation capability for meetings or teaching.
Made of electronic circuits coupled to minute particles, the devices could flow through intestines or pipelines to detect problems.
Researchers produced tiny electronic circuits, just 100 micrometers across, on a substrate material, which was then dissolved away to leave the individual devices floating freely in solution. These were later attached to tiny colloidal particles. Courtesy of the researchers.
Researchers at MIT have created what may be the smallest robots yet that can sense their environment, store data, and even carry out computational tasks. These devices, which are about the size of a human egg cell, consist of tiny electronic circuits made of two-dimensional materials, piggybacking on minuscule particles called colloids.
Colloids – insoluble particles or molecules anywhere from a billionth to a millionth of a meter across – are so small they can stay suspended indefinitely in a liquid or even in air. By coupling these tiny objects to complex circuitry, the researchers hope to lay the groundwork for devices that could be dispersed to carry out diagnostic journeys through anything from the human digestive system to oil and gas pipelines, or perhaps to waft through air to measure compounds inside a chemical processor or refinery.
“We wanted to figure out methods to graft complete, intact electronic circuits onto colloidal particles,” explains Michael Strano, the Carbon C. Dubbs Professor of Chemical Engineering at MIT and senior author of the study, which was published July 23, 2018, in the journal Nature Nanotechnology. MIT postdoc Volodymyr Koman is the paper’s lead author.
“Colloids can access environments and travel in ways that other materials can’t,” Strano says. Dust particles, for example, can float indefinitely in the air because they are small enough that the random motions imparted by colliding air molecules are stronger than the pull of gravity. Similarly, colloids suspended in liquid will never settle out.
Strano says that while other groups have worked on the creation of similarly tiny robotic devices, their emphasis has been on developing ways to control movement, for example by replicating the tail-like flagellae that some microbial organisms use to propel themselves. But Strano suggests that may not be the most fruitful approach, since flagellae and other cellular movement systems are primarily used for local-scale positioning, rather than for significant movement. For most purposes, making such devices more functional is more important than making them mobile, he says.
Tiny robots made by the MIT team are self-powered, requiring no external power source or even internal batteries. A simple photodiode provides the trickle of electricity that the tiny robots’ circuits require to power their computation and memory circuits. That’s enough to let them sense information about their environment, store those data in their memory, and then later have the data read out after accomplishing their mission.
Such devices could ultimately be a boon for the oil and gas industry, Strano says. Currently, the main way of checking for leaks or other issues in pipelines is to have a crew physically drive along the pipe and inspect it with expensive instruments. In principle, the new devices could be inserted into one end of the pipeline, carried along with the flow, and then removed at the other end, providing a record of the conditions they encountered along the way, including the presence of contaminants that could indicate the location of problem areas. The initial proof-of-concept devices didn’t have a timing circuit that would indicate the location of particular data readings, but adding that is part of ongoing work.
Similarly, such particles could potentially be used for diagnostic purposes in the body, for example to pass through the digestive tract searching for signs of inflammation or other disease indicators, the researchers say.
Most conventional microchips, such as silicon-based or CMOS, have a flat, rigid substrate and would not perform properly when attached to colloids that can experience complex mechanical stresses while travelling through the environment. In addition, all such chips are “very energy-thirsty,” Strano says. That’s why Koman decided to try out two-dimensional electronic materials, including graphene and transition-metal dichalcogenides, which he found could be attached to colloid surfaces, remaining operational even after after being launched into air or water. And such thin-film electronics require only tiny amounts of energy. “They can be powered by nanowatts with subvolt voltages,” Koman says.
|Optical images show circuits made by the research team, prior to being attached to particles just a few hundred nanometers across. Image courtesy of the researchers.|
Why not just use the 2-D electronics alone? Without some substrate to carry them, these tiny materials are too fragile to hold together and function. “They can’t exist without a substrate,” Strano says. “We need to graft them to the particles to give them mechanical rigidity and to make them large enough to get entrained in the flow.”
But the 2-D materials “are strong enough, robust enough to maintain their functionality even on unconventional substrates” such as the colloids, Koman says.
The nanodevices they produced with this method are autonomous particles that contain electronics for power generation, computation, logic, and memory storage. They are powered by light and contain tiny retroreflectors that allow them to be easily located after their travels. They can then be interrogated through probes to deliver their data. In ongoing work, the team hopes to add communications capabilities to allow the particles to deliver their data without the need for physical contact.
Other efforts at nanoscale robotics “haven’t reached that level” of creating complex electronics that are sufficiently small and energy efficient to be aerosolized or suspended in a colloidal liquid. These are “very smart particles, by current standards,” Strano says, adding, “We see this paper as the introduction of a new field” in robotics.
The research team, all at MIT, included Pingwei Liu, Daichi Kozawa, Albert Liu, Anton Cottrill, Youngwoo Son, and Jose Lebron. The work was supported by the U.S. Office of Naval Research and the Swiss National Science Foundation.
– David L. Chandler | MIT News Office
July 23, 2018
|Chronicle observes Felice Frankel at work. Courtesy, WCVB Chronicle|
WCVB-TV Boston’s Chronicle highlights the work of MIT Materials Research Laboratory research scientist and photographer Felice Frankel, exploring how she creates visually captivating images of scientific advances. “I want people to love science the way I love science and, in my opinion, the way to get that to happen is to engage them in the visual of the beauty of science,” Frankel says. The segment, which aired Friday, Oct. 13, 2017, is available at WCVB.
Frankel, creator of the MIT edX course, “Making Science and Engineering Pictures: A Practical Guide to Presenting Your Work,” and author of several books on scientific imagery, is currently at work for MIT Press on “Picturing Science and Engineering,” which aims to help scientific researchers to think differently about their work. Frankel also hopes her images will attract children to science.