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Donald Rosenfield, a longtime leader of MIT LGO, dies at 70

With deep sadness, the LGO community mourns its founding program director, Don Rosenfield. He leaves a legacy of over 1,200 LGO alumni and countless colleagues, students, and friends who were touched and inspired by him.
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Reliable energy for all

Prosper Nyovanie (LGO ’19) discusses his passion for using engineering and technology to solve global problems.

 

During high school, Prosper Nyovanie had to alter his daily and nightly schedules to accommodate the frequent power outages that swept cities across Zimbabwe.

“[Power] would go almost every day — it was almost predictable,” Nyovanie recalls. “I’d come back from school at 5 p.m., have dinner, then just go to sleep because the electricity wouldn’t be there. And then I’d wake up at 2 a.m. and start studying … because by then you’d usually have electricity.”

At the time, Nyovanie knew he wanted to study engineering, and upon coming to MIT as an undergraduate, he majored in mechanical engineering. He discovered a new area of interest, however, when he took 15.031J (Energy Decisions, Markets, and Policies), which introduced him to questions of how energy is produced, distributed, and consumed. He went on to minor in energy studies.

Now as a graduate student and fellow in MIT’s Leaders for Global Operations (LGO) program, Nyovanie is on a mission to learn the management skills and engineering knowledge he needs to power off-grid communities around the world through his startup, Voya Sol. The company develops solar electric systems that can be scaled to users’ needs.

Determination and quick thinking

Nyovanie was originally drawn to MIT for its learning-by-doing engineering focus. “I thought engineering was a great way to take all these cool scientific discoveries and technologies and apply them to global problems,” he says. “One of the things that excited me a lot about MIT was the hands-on approach to solving problems. I was super excited about UROP [the Undergraduate Research Opportunities Program]. That program made MIT stick out from all the other universities.”

As a mechanical engineering major, Nyovanie took part in a UROP for 2.5 years in the Laboratory for Manufacturing and Productivity with Professor Martin Culpepper. But his experience in 15.031J made him realize his interests were broader than just research, and included the intersection of technology and business.

“One big thing that I liked about the class was that it introduced this other complexity that I hadn’t paid that much attention to before, because when you’re in the engineering side, you’re really focused on making technology, using science to come up with awesome inventions,” Nyovanie says. “But there are considerations that you need to think about when you’re implementing [such inventions]. You need to think about markets, how policies are structured.”

The class inspired Nyovanie to become a fellow in the LGO program, where he will earn an MBA from the MIT Sloan School of Management and a master’s in mechanical engineering. He is also a fellow of the Legatum Center for Development and Entrepreneurship at MIT.

When Nyovanie prepared for his fellowship interview while at home in Zimbabwe, he faced another electricity interruption: A transformer blew and would take time to repair, leaving him without power before his interview.

“I had to act quickly,” Nyovanie says. “I went and bought a petrol generator just for the interview. … The generator provided power for my laptop and for the Wi-Fi.” He recalls being surrounded by multiple solar lanterns that provided enough light for the video interview.

While Nyovanie’s determination in high school and quick thinking before graduate school enabled him to work around power supply issues, he realizes that luxury doesn’t extend to all those facing similar situations.

“I had enough money to actually go buy a petrol generator. Some of these communities in off-grid areas don’t have the resources they need to be able to get power,” Nyovanie says.

Scaling perspectives

Before co-founding Voya Sol with Stanford University graduate student Caroline Jo, Nyovanie worked at SunEdison, a renewable energy company, for three years. During most of that time, Nyovanie worked as a process engineer and analyst through the Renewable Energy Leadership Development Rotational Program. As part of the program, Nyovanie rotated between different roles at the company around the world.

During his last rotation, Nyovanie worked as a project engineer and oversaw the development of rural minigrids in Tanzania. “That’s where I got firsthand exposure to working with people who don’t have access to electricity and working to develop a solution for them,” Nyovanie says. When SunEdison went bankrupt, Nyovanie wanted to stay involved in developing electricity solutions for off-grid communities. So, he stayed in talks with rural electricity providers in Zimbabwe, Kenya, and Nigeria before eventually founding Voya Sol with Jo.

Voya Sol develops scalable solar home systems which are different than existing solar home system technologies. “A lot of them are fixed,” Nyovanie says. “So if you buy one, and need an additional light, then you have to go buy another whole new system. … The scalable system would take away some of that risk and allow the customer to build their own system so that they buy a system that fits their budget.” By giving users the opportunity to scale up or scale down their wattage to meet their energy needs, Nyovanie hopes that the solar electric systems will help power off-grid communities across the world.

Nyovanie and his co-founder are currently both full-time graduate students in dual degree programs. But to them, graduate school didn’t necessarily mean an interruption to their company’s operations; it meant new opportunities for learning, mentorship, and team building. Over this past spring break, Nyovanie and Jo traveled to Zimbabwe to perform prototype testing for their solar electric system, and they plan to conduct a second trip soon.

“We’re looking into ways we can aggregate people’s energy demands,” Nyovanie says. “Interconnected systems can bring in additional savings for customers.” In the future, Nyovanie hopes to expand the distribution of scalable solar electric systems through Voya Sol to off-grid communities worldwide. Voya Sol’s ultimate vision is to enable off-grid communities to build their own electricity grids, by allowing individual customers to not only scale their own systems, but also interconnect their systems with their neighbors’. “In other words, Voya Sol’s goal is to enable a completely build-your-own, bottom-up electricity grid,” Nyovanie says.

Supportive communities

During his time as a graduate student at MIT, Nyovanie has found friendship and support among his fellow students.

“The best thing about being at MIT is that people are working on all these cool, different things that they’re passionate about,” Nyovanie says. “I think there’s a lot of clarity that you can get just by going outside of your circle and talking to people.”

Back home in Zimbabwe, Nyovanie’s family cheers him on.

“Even though [my parents] never went to college, they were very supportive and encouraged me to push myself, to do better, and to do well in school, and to apply to the best programs that I could find,” Nyovanie says.

June 12, 2018 | More

LGO Best Thesis 2018 for Predictive Modeling Project at Massachusetts General Hospital

After the official MIT commencement ceremonies, Thomas Roemer, LGO’s executive director, announced the best thesis winner at LGO’s annual post-graduation celebration. This year’s winner was Jonathan Zanger, who developed a predictive model using machine learning at Massachusetts General Hospital. “The thesis describes breakthrough work at MGH that leverages machine learning and deep clinical knowledge to develop a decision support tool to predict discharges from the hospital in the next 24-48 hours and enable a fundamentally new and more effective discharge process,” said MIT Sloan School of Management Professor Retsef Levi, one of Zanger’s thesis advisors and the LGO management faculty co-director.

Applying MIT knowledge in the real world

Best Thesis 2018
Jonathan Zanger won the 2018 LGO best thesis award for his work using machine learning to develop a predictive model for better patient care at MGH

Zanger, who received his MBA and an SM in Electrical Engineering and Computer Science, conducted his six-month LGO internship project at MGH that sought to enable a more proactive process of managing the hospital’s bed capacity by identifying which surgical inpatients are likely to be discharged from the hospital in the next 24 to 48 hours. To do this, Zanger grouped patients by their surgery type, and worked to define and formalize milestones on the pathway to a post-operative recovery by defining barriers that may postpone patients’ discharge. Finally, he used a deep learning algorithm which uses over 900 features and is trained on 3000 types of surgeries and 20,000 surgical discharges. LGO thesis advisor Retsef Levi stated that “in my view, this thesis work represents a league of its own in terms of technical depth, creativity and potential impact.” Zanger was able to have true prediction for 97% of patients discharged within 48 hours. This helps to limit overcrowding and operational disruptions and anticipate capacity crises.

A group of faculty, alumni and staff review the theses each year to determine the winner. Thomas Sanderson (LGO ’14), LGO alumni and thesis reviewer stated that Zanger’s thesis showed  “tremendous extensibility and smart solution architecture decisions to make future work easy. Obvious and strong overlap of engineering, business, and industry.  This is potentially revolutionary work; this research advances the current state of the art well beyond anything currently available for large hospital bed management with obvious and immediate impact on healthcare costs and patient outcomes. The theory alone is hugely noteworthy but the fact that the work was also piloted during the thesis period is even more impressive. LGO has done a lot of great work at MGH but this is potentially the widest reaching and most important.”

Zanger, who earned his undergraduate degree Physics, Computer Science and Mathematics from the Hebrew University of Jerusalem, will return to Israel after graduation and resume service as an Israeli Defense Forces officer.

June 11, 2018 | More

A graphene roll-out

LGO thesis advisor and MIT Mechanical Engineering Professor John Hart, lead a team to develop a continuous manufacturing process that produces long strips of high-quality graphene.

The team’s results are the first demonstration of an industrial, scalable method for manufacturing high-quality graphene that is tailored for use in membranes that filter a variety of molecules, including salts, larger ions, proteins, or nanoparticles. Such membranes should be useful for desalination, biological separation, and other applications.

“For several years, researchers have thought of graphene as a potential route to ultrathin membranes,” says John Hart, associate professor of mechanical engineering and director of the Laboratory for Manufacturing and Productivity at MIT. “We believe this is the first study that has tailored the manufacturing of graphene toward membrane applications, which require the graphene to be seamless, cover the substrate fully, and be of high quality.”

Hart is the senior author on the paper, which appears online in the journal Applied Materials and Interfaces. The study includes first author Piran Kidambi, a former MIT postdoc who is now an assistant professor at Vanderbilt University; MIT graduate students Dhanushkodi Mariappan and Nicholas Dee; Sui Zhang of the National University of Singapore; Andrey Vyatskikh, a former student at the Skolkovo Institute of Science and Technology who is now at Caltech; and Rohit Karnik, an associate professor of mechanical engineering at MIT.

Growing graphene

For many researchers, graphene is ideal for use in filtration membranes. A single sheet of graphene resembles atomically thin chicken wire and is composed of carbon atoms joined in a pattern that makes the material extremely tough and impervious to even the smallest atom, helium.

Researchers, including Karnik’s group, have developed techniques to fabricate graphene membranes and precisely riddle them with tiny holes, or nanopores, the size of which can be tailored to filter out specific molecules. For the most part, scientists synthesize graphene through a process called chemical vapor deposition, in which they first heat a sample of copper foil and then deposit onto it a combination of carbon and other gases.

Graphene-based membranes have mostly been made in small batches in the laboratory, where researchers can carefully control the material’s growth conditions. However, Hart and his colleagues believe that if graphene membranes are ever to be used commercially they will have to be produced in large quantities, at high rates, and with reliable performance.

“We know that for industrialization, it would need to be a continuous process,” Hart says. “You would never be able to make enough by making just pieces. And membranes that are used commercially need to be fairly big ­— some so big that you would have to send a poster-wide sheet of foil into a furnace to make a membrane.”

A factory roll-out

The researchers set out to build an end-to-end, start-to-finish manufacturing process to make membrane-quality graphene.

The team’s setup combines a roll-to-roll approach — a common industrial approach for continuous processing of thin foils — with the common graphene-fabrication technique of chemical vapor deposition, to manufacture high-quality graphene in large quantities and at a high rate. The system consists of two spools, connected by a conveyor belt that runs through a small furnace. The first spool unfurls a long strip of copper foil, less than 1 centimeter wide. When it enters the furnace, the foil is fed through first one tube and then another, in a “split-zone” design.

While the foil rolls through the first tube, it heats up to a certain ideal temperature, at which point it is ready to roll through the second tube, where the scientists pump in a specified ratio of methane and hydrogen gas, which are deposited onto the heated foil to produce graphene.

Graphene starts forming in little islands, and then those islands grow together to form a continuous sheet,” Hart says. “By the time it’s out of the oven, the graphene should be fully covering the foil in one layer, kind of like a continuous bed of pizza.”

As the graphene exits the furnace, it’s rolled onto the second spool. The researchers found that they were able to feed the foil continuously through the system, producing high-quality graphene at a rate of 5 centimers per minute. Their longest run lasted almost four hours, during which they produced about 10 meters of continuous graphene.

“If this were in a factory, it would be running 24-7,” Hart says. “You would have big spools of foil feeding through, like a printing press.”

Flexible design

Once the researchers produced graphene using their roll-to-roll method, they unwound the foil from the second spool and cut small samples out. They cast the samples with a polymer mesh, or support, using a method developed by scientists at Harvard University, and subsequently etched away the underlying copper.

“If you don’t support graphene adequately, it will just curl up on itself,” Kidambi says. “So you etch copper out from underneath and have graphene directly supported by a porous polymer — which is basically a membrane.”

The polymer covering contains holes that are larger than graphene’s pores, which Hart says act as microscopic “drumheads,” keeping the graphene sturdy and its tiny pores open.

The researchers performed diffusion tests with the graphene membranes, flowing a solution of water, salts, and other molecules across each membrane. They found that overall, the membranes were able to withstand the flow while filtering out molecules. Their performance was comparable to graphene membranes made using conventional, small-batch approaches.

The team also ran the process at different speeds, with different ratios of methane and hydrogen gas, and characterized the quality of the resulting graphene after each run. They drew up plots to show the relationship between graphene’s quality and the speed and gas ratios of the manufacturing process. Kidambi says that if other designers can build similar setups, they can use the team’s plots to identify the settings they would need to produce a certain quality of graphene.

“The system gives you a great degree of flexibility in terms of what you’d like to tune graphene for, all the way from electronic to membrane applications,” Kidambi says.

Looking forward, Hart says he would like to find ways to include polymer casting and other steps that currently are performed by hand, in the roll-to-roll system.

“In the end-to-end process, we would need to integrate more operations into the manufacturing line,” Hart says. “For now, we’ve demonstrated that this process can be scaled up, and we hope this increases confidence and interest in graphene-based membrane technologies, and provides a pathway to commercialization.”

May 18, 2018 | More

This MIT program will purchase carbon offsets for student travel

Lead by Yakov Berenshteyn, (LGO ’19) a new Jetset Offset program will reduce the environmental impact of student travel by purchasing carbon offsets.

In one week about 100 MIT Sloan students will fly around the world to study regional economies, immerse themselves in different cultures, and produce more than 300 metric tons [PDF] of carbon dioxide.

Thanks to the necessary air travel for study tours, those students are producing the same emissions in two weeks as 1,600 average American car commuters would in that same timeframe, said Yakov Berenshteyn, LGO ’19.

While Berenshteyn doesn’t want to do away with student travel at MIT Sloan, he is hoping to lessen the impact on the environment, with the help of his Jetset Offset program.

The pilot involves purchasing carbon offsets for the three MBA and one Master of Finance study tours for spring break 2018.

Carbon offsets are vetted projects that help capture or avoid carbon emissions. These projects can include reforestation and building renewable energy sources. The reductions might not have an immediate impact on emissions, Berenshteyn said, but they are “still the primary best practice for us to use.”

“This is raising awareness of, and starting to account for, our environmental impacts from student travel,” Berenshteyn said. “You don’t get much choice in the efficiency of the airplane that you board.”

The idea for the offset came in October, when Berenshteyn was helping to plan the January Leaders for Global Operations Domestic Plant Trek. Berenshteyn at the time realized for the two weeks of the trip, the roughly 50 students and staff would be logging a total of 400,000 air miles.

Berenshteyn spent months researching an answer for counterbalancing the burned jet fuel. He also got input from MIT Sloan professor John Sterman. Berenshteyn said he looked at other options, like funding more local projects such as solar panel installation, but the calculations were too small scale to make much of a difference.

Universities around the world are applying carbon offsets and carbon-neutral practices in some form to their operations. Berenshteyn said Duke University has something similar to the air travel and carbon offsets that he proposes for MIT Sloan.

The Leaders for Global Operations program purchased 67 metric tons of offsets through Gold Standard for the January student trek, and those offsets are going to reforestation efforts in Panama.

In the case of the four upcoming study trips, MIT Sloan’s student life office is picking up the tab.

“My colleague Paul Buckley (associate director of student life) had an idea for something like this close to a decade ago, when he first arrived in student life, and noted the extent to which our students travel during their time at Sloan,” said Katie Ferrari, associate director of student life. “So this was an especially meaningful partnership for us. Yakov’s idea is exactly the kind of student initiative we love to support. He is practicing principled, innovative leadership with an eye toward improving the world.”

Ferrari said the support for the pilot this semester is a stake in the ground for incorporating carbon offset purchases into future student-organized travel — which is what Berenshteyn said was his hope for launching the pilot.

“It should be at Sloan, if a student is planning a trip, they have their checklist of insurance, emergency numbers, and carbon offsets,” he said.

March 21, 2018 | More

A machine-learning approach to inventory-constrained dynamic pricing

LGO thesis advisor and MIT Civil and Environmental Engineering Professor David Simchi-Levi lead a team on a new study showing how a model-based algorithm known as Thompson sampling can be used for revenue management.

In 1933, William R. Thompson published an article on a Bayesian model-based algorithm that would ultimately become known as Thompson sampling. This heuristic was largely ignored by the academic community until recently, when it became the subject of intense study, thanks in part to internet companies that successfully implemented it for online ad display.

Thompson sampling chooses actions for addressing the exploration-exploitation in the multiarmed bandit problem to maximize performance and continually learn, acquiring new information to improve future performance.

In a new study, “Online Network Revenue Management Using Thompson Sampling,” MIT Professor David Simchi-Levi and his team have now demonstrated that Thompson sampling can be used for a revenue management problem, where demand function is unknown.

Incorporating inventory constraints

A main challenge to adopting Thompson sampling for revenue management is that the original method does not incorporate inventory constraints. However, the authors show that Thompson sampling can be naturally combined with a classical linear program formulation to include inventory constraints.

The result is a dynamic pricing algorithm that incorporates domain knowledge and has strong theoretical performance guarantees as well as promising numerical performance results.

Interestingly, the authors demonstrate that Thompson sampling achieves poor performance when it does not take into account domain knowledge.

Simchi-Levi says, “It is exciting to demonstrate that Thomson sampling can be adapted to combine a classical linear program formulation, to include inventory constraints, and to see that this method can be applied to general revenue management problems in the business-to-consumer and business-to-business environments.”

Industry application improves revenue

The proposed dynamic pricing algorithm is highly flexible and is applicable in a range of industries, from airlines and internet advertising all the way to online retailing.

The new study, which has just been accepted by the journal Operations Research, is part of a larger research project by Simchi-Levi that combines machine learning and stochastic optimization to improve revenue, margins, and market share.

Algorithms developed in this research stream have been implemented at companies such as Groupon, a daily market maker, Rue La La, a U.S. online flash sales retailer, B2W Digital, a large online retailer in Latin America, and at a large brewing company, where Simchi-Levi and his team optimized the company’s promotion and pricing in various retail channels.


March 19, 2018 | More

A revolutionary model to optimize promotion pricing

William F. Pounds Professor of Management and LGO thesis advisor Georgia Perakis recently authored a Huffington Post article about using a scientific, data-driven approach to determine optimal promotion pricing.
Grocery stores run price promotions all the time. You see them when a particular brand of spaghetti sauce is $1 off or your favorite coffee is buy one get one free. Promotions are used for a variety of reasons from increasing traffic in stores to boosting sales of a particular brand. They are responsible for a lot of revenue, as a 2009 A.C. Nielsen study found that 42.8% of grocery store sales in the U.S. are made during promotions. This raises an important question: How much money does a retailer leave on the table by using current pricing practices as opposed to a more scientific, data-driven approach in order to determine optimal promotional prices?

The promotion planning tools currently available in the industry are mostly manual and based on “what-if” scenarios. In other words, supermarkets tend to use intuition and habit to decide when, how deep, and how often to promote products. Yet promotion pricing is very complicated. Product managers have to solve problems like whether or not to promote an item in a particular week, whether or not to promote two items together, and how to order upcoming discounts ― not to mention incorporating seasonality issues in their decision-making process.

There are plenty of people in the industry with years of experience who are good at this, but their brains are not computers. They can’t process the massive amounts of data available to determine optimal pricing. As a result, lots of money is left on the table.

To revolutionize the field of promotion pricing, my team of PhD students from the Operations Research Center at MIT, our collaborators from Oracle, and I sought to build a model based on several goals. It had to be simple and realistic. It had to be easy to estimate directly from the data, but also computationally easy and scalable. In addition, it had to lead to interesting and valuable results for retailers in practice.

Read the full post at The Huffington Post.

Georgia Perakis is the William F. Pounds Professor of Management and a Professor of Operations Research and Operations Management at the MIT Sloan School of Management.

March 16, 2018 | More

JDA Software collaborates with MIT to advance research in intelligent supply chains

David Simchi-Levi, Professor of Civil and Environmental Engineering and LGO thesis advisor is leading a multiyear collaboration with JDA Software.

MIT will work with JDA, leveraging their business domain expertise and client base, to advance research in intelligent supply chains.

The collaboration aims to improve supply chain performance and customer experiences by leveraging data, computational power, and machine learning.

Professor of civil and environmental engineering David Simchi-Levi says, “I am very pleased JDA has entered into a multiyear research collaboration with MIT, and I look forward to working with the JDA Lab and teams. The collaboration will support our students and advance research in machine learning, optimization and consumer behavior modeling. “

This collaboration with JDA brings real world challenges, opportunities, and data, and will help to further the advancement of MIT’s world-class research in supply chain and retail analytics.

The MIT and JDA research teams will create real-world use cases to expand predictive demand, intelligent execution, and smart supply chain and retail planning that will yield a unique business strategy. These use cases will explore new data science algorithms that combine natural language processing, predictive behavior, and prescriptive optimization by taking into account past behaviors, and predicting and changing future behaviors.

“It is more critical than ever to infuse innovation into every aspect of the supply chain, as edge technologies such as the Internet of Things (IoT) and artificial intelligence (AI) are essential to digitally transforming supply chains. This collaboration allows us to tap into the extraordinary mindshare at MIT to accelerate the research into more intelligent and cognitive capabilities moving forward,” says Desikan Madhavanur, executive vice president and chief development officer at JDA.

“We are excited to be working on the future of supply chain with MIT to double down on researching enhanced, innovative, and value-driven supply chain solutions,” Madhavanur says.

The multiyear collaboration will support students on the research teams and the development of knowledge and education.

Simchi-Levi will speak at JDA’s annual customer conference, JDA FOCUS 2018, in Orlando, May 6-9, 2018.

March 16, 2018 | More

Making appliances and energy grids more efficient

Professor of electrical engineering and frequent LGO thesis advisor James Kirtley Jr., is working on a new design for fans that offers high efficiency at an affordable cost, which could have a huge impact for developing countries.

The ceiling fan is one of the most widely used mechanical appliances in the world. It is also, in many cases, one of the least efficient.

In India, ceiling fans have been used for centuries to get relief from the hot, humid climate. Hand-operated fans called punkahs can be traced as far back as 500 BC and were fixtures of life under the British Raj in the 18th and 19th centuries. Today’s ceiling fans run on electricity and are more ubiquitous than ever. The Indian Fan Manufacturers’ Association reported producing 40 million units in 2014 alone, and the number of fans in use nationwide is estimated in the hundreds of millions, perhaps as many as half a billion.

James Kirtley Jr., a professor of electrical engineering at MIT, has been investigating the efficiency of small motors like those found in ceiling fans for more than 30 years.

“A typical ceiling fan in India draws about 80 watts of electricity, and it does less than 10 watts of work on the air,” he says. “That gives you an efficiency of just 12.5 percent.”

Low-efficiency fans pose a variety of energy problems. Consumers don’t get good value for the electricity they buy from the grid, and energy utilities have to deal with the power losses and grid instability that result from low-quality appliances.

But there’s a reason these low-efficiency fans, driven by single-phase induction motors, are so popular: They’re inexpensive. “The best fans on the market in India — those that move a reasonable amount of air and have a low input power — are actually quite costly,” Kirtley says. The high price puts them out of reach for most of India’s population.

Now Kirtley, with support from the Tata Center for Technology and Design, is working on a single-phase motor design that offers high efficiency at an affordable cost. He says the potential impact is huge.

“If every fan in India saved just 2 watts of electricity, that would be the equivalent of a nuclear power plant’s generation capacity,” he says. “If we could make these fans substantially more efficient than they are, operating off of DC electricity, you could imagine extending the use of ceiling fans into rural areas where they could provide a benefit to the quality of life.”

Mohammad Qasim, a graduate student in Kirtley’s research group and a fellow in the Tata Center, says the benefits could reach multiple stakeholders. “Having more efficient appliances means a lower electricity bill for the consumer and fewer power losses on the utility’s side,” he says.

Choosing the right motor

“The idea is to try and hit that high-efficiency mark at a cost that is only a little more than that of existing low-efficiency fans,” Kirtley says. “We imagine a fan that might have an input power of 15 watts and an efficiency of 75 percent.”

To accomplish that, Kirtley and Qasim are exploring two approaches: creating an improved version of the conventional induction motor, or switching to a brushless DC motor, which may be more expensive but can deliver superior efficiency.

In either case, they plan to use power electronics — devices that control and optimize the flow of electricity through the motor — to improve the power quality and grid compatibility of the fan. Power electronics can also be used to convert AC electricity from the grid into DC, opening up the possibility of using DC motors in ceiling fans.

Brushless DC motors, which are the younger technology, use permanent magnets to establish a magnetic field that creates torque between the motor’s two main components, the rotor and stator. “You can think of it almost like a dog chasing his tail,” Kirtley says. “If I establish the magnetic field in some direction, the magnet turns to align itself in that direction. As I rotate the magnetic field, the magnet moves to align, and that keeps the rotor spinning.”

Induction motors, on the other hand, use no magnets but instead create a rotating magnetic field by flowing current through the stator coils. Because they use AC electricity, they are directly grid compatible, but their efficiency and stability can be improved by using power electronics to optimize the speed of the motor.

International collaboration

In determining which path to take, induction or brushless DC motor, Kirtley and Qasim are leaning on the expertise of Vivek Agarwal, a professor of electrical engineering at the Indian Institute of Technology, Bombay (IITB). Agarwal is a specialist in power electronics.

“The collaboration with Professor Agarwal’s group is so important,” Kirtley says. “They can give us a good idea of what the two different power electronics packages will cost. You would typically think of the brushless motor package as the more expensive option, but it may or may not be.”

Outside of the lab, on-the-ground detective work is key. When Qasim visited India in January 2017, he hit the streets of Mumbai with one of the graduate students from Agarwal’s lab. Together, they visited people across the ceiling fan industry, from manufacturers to repairmen in street-side shops.

“This visit was a big motivation for us,” says Qasim, noting that they were able to glean insights that will help them design a more robust and durable motor. “We want to understand the major maintenance issues that cause these motors to break down so that we can avoid common sources of failure. It was important to make the effort to talk to local people who had real experience repairing these motors.”

Usha International, an appliance manufacturer based in New Delhi, has been a key advisor in the early stages of the project and helped identify ceiling fans as a critical focus area. Engineers at Usha agree with Kirtley’s assessment that there is an unmet need for high-efficiency motors at relatively low cost, and Qasim says the Usha team shared what they had learned from designing their own high-efficiency fans.

Now, Kirtley and Qasim are engaged in the daunting task of envisioning how an ideal motor might look.

“This is a very challenging problem, to design a motor that is both efficient and inexpensive,” Kirtley says. “There’s still a question of which type of motor is going to be the best one to pursue. If we can get a good understanding of what exactly the machine ought to do, we can proceed to do a good machine design.”

Qasim has built a test facility in Kirtley’s laboratory at MIT, which he is using to characterize a variety of existing fans. His experimental data, combined with his fieldwork in India, should provide a set of design requirements for the improved motor. From there, he and Kirtley will work with the IITB researchers to pair the machine with an appropriate power electronics package.

In reducing the power demands of the standard ceiling fan by as much as 65 watts, they hope to have a far-reaching, positive effect on India’s energy system. But that’s only the start. Ultimately, they believe efficient, affordable motors can be applied to a number of common appliances, potentially saving gigawatts of electricity in a country that is working hard to expand reliable energy access for what will soon be the world’s largest population.

This article appeared in the Autumn 2017 issue of Energy Futures, the magazine of the MIT Energy Initiative.


March 2, 2018 | More

Urban heat island effects depend on a city’s layout

Franz-Josef Ulm, professor of civil and environmental engineering and LGO thesis advisor lead a recent study in the urban heat island effect, which causes cities to be hotter than their surroundings. The research will improve future building in hot locations to minimize extra heating.

The arrangement of a city’s streets and buildings plays a crucial role in the local urban heat island effect, which causes cities to be hotter than their surroundings, researchers have found. The new finding could provide city planners and officials with new ways to influence those effects.

Some cities, such as New York and Chicago, are laid out on a precise grid, like the atoms in a crystal, while others such as Boston or London are arranged more chaotically, like the disordered atoms in a liquid or glass. The researchers found that the “crystalline” cities had a far greater buildup of heat compared to their surroundings than did the “glass-like” ones.

The study, published today in the journal Physical Review Letters, found these differences in city patterns, which they call “texture,” was the most important determinant of a city’s heat island effect. The research was carried out by MIT and National Center for Scientific Research senior research scientist Roland Pellenq, who is also director of a joint MIT/ CNRS/Aix-Marseille University laboratory called <MSE>2 (MultiScale Material Science for Energy and Environment); professor of civil and environmental engineering Franz-Josef Ulm; research assistant Jacob Sobstyl; <MSE>2 senior research scientist T. Emig; and M.J. Abdolhosseini Qomi, assistant professor of civil and environmental engineering at the University of California at Irvine.

The heat island effect has been known for decades. It essentially results from the fact that urban building materials, such as concrete and asphalt, can absorb heat during the day and radiate it back at night, much more than areas covered with vegetation do. The effect can be quite dramatic, adding as much as 10 degrees Farenheit to night-time temperatures in places such as Phoenix, Arizona. In such places this effect can significantly increase health problems and energy use during hot weather, so a better understanding of what produces it will be important in an era when ever more people are living in cities.

The team found that using mathematical models that were developed to analyze atomic structures in materials provides a useful tool, leading to a straightforward formula to describe the way a city’s design would influence its heat-island effect, Pellenq says.

“We use tools of classical statistical physics,” he explains. The researchers adapted formulas initially devised to describe how individual atoms in a material are affected by forces from the other atoms, and they reduced these complex sets of relationships to much simpler statistical descriptions of the relative distances of nearby buildings to each other. They then applied them to patterns of buildings determined from satellite images of 47 cities in the U.S. and other countries, ultimately ending up with a single index number for each — called the local order parameter — ranging between 0 (total disorder) and 1 (perfect crystalline structure), to provide a statistical description of the cluster of nearest neighbors of any given building.

For each city, they had to collect reliable temperature data, which came from one station within the city and another outside it but nearby, and then determine the difference.

To calculate this local order parameter, physicists typically have to use methods such as bombarding materials with neutrons to locate the positions of atoms within them. But for this project, Pellenq says, “to get the building positions we don’t use neutrons, just Google maps.” Using algorithms they developed to determine the parameter from the city maps, they found that the cities varied from 0.5 to 0.9.

The differences in the heating effect seem to result from the way buildings reradiate heat that can then be reabsorbed by other buildings that face them directly, the team determined.

Especially for places such as China where new cities are rapidly being built, and other regions where existing cities are expanding rapidly, the information could be important to have, he says. In hot locations, cities could be designed to minimize the extra heating, but in colder places the effect might actually be an advantage, and cities could be designed accordingly.

“If you’re planning a new section of Phoenix,” Pellenq says, “you don’t want to build on a grid, since it’s already a very hot place. But somewhere in Canada, a mayor may say no, we’ll choose to use the grid, to keep the city warmer.”

The effects are significant, he says. The team evaluated all the states individually and found, for example, that in the state of Florida alone urban heat island effects cause an estimated $400 million in excess costs for air conditioning. “This gives a strategy for urban planners,” he says. While in general it’s simpler to follow a grid pattern, in terms of placing utility lines, sewer and water pipes, and transportation systems, in places where heat can be a serious issue, it can be well worth the extra complications for a less linear layout.

This study also suggests that research on construction materials may offer a way forward to properly manage heat interaction between buildings in cities’ historical downtown areas.

The work was partly supported by the Concrete Sustainability Hub at MIT, sponsored by the Portland Cement Association and the Ready-Mixed Concrete Research and Education Foundation.

February 22, 2018 | More

Getting to the heart of carbon nanotube clusters

Brian Wardle, LGO thesis advisor and professor of aeronautics and astronautics, has led a team of MIT researches in the development of a systematic method to predict the two-dimensional patterns carbon nanotubes (CNTs).

Integrating nanoscale fibers such as carbon nanotubes (CNTs) into commercial applications, from coatings for aircraft wings to heat sinks for mobile computing, requires them to be produced in large scale and at low cost. Chemical vapor deposition (CVD) is a promising approach to manufacture CNTs in the needed scales, but it produces CNTs that are too sparse and compliant for most applications.

Applying and evaporating a few drops of a liquid such as acetone to the CNTs is an easy, cost-effective method to more tightly pack them together and increase their stiffness, but until now, there was no way to forecast the geometry of these CNT cells.

MIT researchers have now developed a systematic method to predict the two-dimensional patterns CNT arrays form after they are packed together, or densified, by evaporating drops of either acetone or ethanol. CNT cell size and wall stiffness grow proportionally with cell height, they report in the Feb. 14 issue of Physical Chemistry Chemical Physics.

One way to think of this CNT behavior is to imagine how entangled fibers such as wet hair or spaghetti collectively reinforce each other. The larger this entangled region is, the higher its resistance to bending will be. Similarly, longer CNTs can better reinforce one another in a cell wall. The researchers also find that CNT binding strength to the base on which they are produced, in this case, silicon, makes an important contribution to predicting the cellular patterns that these CNTs will form.

“These findings are directly applicable to industry because when you use CVD, you get nanotubes that have curvature, randomness, and are wavy, and there is a great need for a method that can easily mitigate these defects without breaking the bank,” says Itai Stein SM ’13, PhD ’16, who is a postdoc in the Department of Aeronautics and Astronautics. Co-authors include materials science and engineering graduate student Ashley Kaiser, mechanical engineering postdoc Kehang Cui, and senior author Brian Wardle, professor of aeronautics and astronautics.

“From our previous work on aligned carbon nanotubes and their composites, we learned that more tightly packing the CNTs is a highly effective way to engineer their properties,” says Wardle. “The challenging part is to develop a facile way of doing this at scales that are relevant to commercial aircraft (hundreds of meters), and the predictive capabilities that we developed here are a large step in that direction.”

Detailed measurements

Carbon nanotubes are highly desirable because of their thermal, electrical, and mechanical properties, which are directionally dependent. Earlier work in Wardle’s lab demonstrated that waviness reduces the stiffness of CNT arrays by as little as 100 times, and up to 100,000 times. The technical term for this stiffness, or ability to bend without breaking, is elastic modulus. Carbon nanotubes are from 1,000 to 10,000 times longer than they are thick, so they deform principally along their length.

For an earlier paper published in the journal Applied Physics Letters, Stein and colleagues used nanoindentation techniques to measure stiffness of aligned carbon nanotube arrays and found their stiffness to be 1/1,000 to 1/10,000 times less than the theoretical stiffness of individual carbon nanotubes. Stein, Wardle, and former visiting MIT graduate student Hülya Cebeci also developed a theoretical model explaining changes at different packing densities of the nanofibers.

The new work shows that CNTs compacted by the capillary forces from first wetting them with acetone or ethanol and then evaporating the liquid also produces CNTs that are hundreds to thousands of times less stiff than expected by theoretical values. This capillary effect, known as elastocapillarity, is similar to a how a sponge often dries into a more compact shape after being wetted and then dried.

“Our findings all point to the fact that the CNT wall modulus is much lower than the normally assumed value for perfect CNTs because the underlying CNTs are not straight,” says Stein. “Our calculations show that the CNT wall is at least two orders of magnitude less stiff than we expect for straight CNTs, so we can conclude that the CNTs must be wavy.”

Heat adds strength

The researchers used a heating technique to increase the adhesion of their original, undensified CNT arrays to their silicon wafer substrate. CNTs densified after heat treatment were about four times harder to separate from the silicon base than untreated CNTs. Kaiser and Stein, who share first authorship of the paper, are currently developing an analytical model to describe this phenomenon and tune the adhesion force, which would further enable prediction and control of such structures.

“Many applications of vertically aligned carbon nanotubes [VACNTs], such as electrical interconnects, require much denser arrays of nanotubes than what is typically obtained for as-grown VACNTs synthesized by chemical vapor deposition,” says Mostafa Bedewy, assistant professor at the University of Pittsburgh, who was not involved in this work. “Hence, methods for postgrowth densification, such as those based on leveraging elastocapillarity have previously been shown to create interesting densified CNT structures. However, there is still a need for a better quantitative understanding of the factors that govern cell formation in densified large-area arrays of VACNTs. The new study by the authors contributes to addressing this need by providing experimental results, coupled with modeling insights, correlating parameters such as VACNT height and VACNT-substrate adhesion to the resulting cellular morphology after densification.

“There are still remaining questions about how the spatial variation of CNT density, tortuosity [twist], and diameter distribution across the VACNT height affects the capillary densification process, especially since vertical gradients of these features can be different when comparing two VACNT arrays having different heights,” says Bedewy. “Further work incorporating spatial mapping of internal VACNT morphology would be illuminating, although it will be challenging as it requires combining a suite of characterization techniques.”

Picturesque patterns

Kaiser, who was a 2016 MIT Summer Scholar, analyzed the densified CNT arrays with scanning electron microscopy (SEM) in the MIT Materials Research Laboratory’s NSF-MRSEC-supported Shared Experimental Facilities. While gently applying liquid to the CNT arrays in this study caused them to densify into predictable cells, vigorously immersing the CNTs in liquid imparts much stronger forces to them, forming randomly shaped CNT networks. “When we first started exploring densification methods, I found that this forceful technique densified our CNT arrays into highly unpredictable and interesting patterns,” says Kaiser. “As seen optically and via SEM, these patterns often resembled animals, faces, and even a heart — it was a bit like searching for shapes in the clouds.” A colorized version of her optical image showing a CNT heart is featured on the cover of the Feb. 14 print edition of Physical Chemistry Chemical Physics.

“I think there is an underlying beauty in this nanofiber self-assembly and densification process, in addition to its practical applications,” Kaiser adds. “The CNTs densify so easily and quickly into patterns after simply being wet by a liquid. Being able to accurately quantify this behavior is exciting, as it may enable the design and manufacture of scalable nanomaterials.”

This work made use of the MIT Materials Research Laboratory Shared Experimental Facilities, which are supported in part by the MRSEC Program of the National Science Foundation, and MIT Microsystems Technology Laboratories. This research was supported in part by Airbus, ANSYS, Embraer, Lockheed Martin, Saab AB, Saertex, and Toho Tenax through MIT’s Nano-Engineered Composite Aerospace Structures Consortium and by NASA through the Institute for Ultra-Strong Composites by Computational Design.

February 15, 2018 | More

Sloan

Here’s how ‘question bursts’ make better brainstorms

Here’s how ‘question bursts’ make better brainstorms

It’s among the largest of projects that Ling Xiang, a director of product management at Oracle, has encountered: helping to lead an organizational change that is part of the company’s transformation from a software developer into a cloud-based service provider.

The transition will require bucking old ways of thinking to adopt new ones. But Xiang expects such a drastic shift won’t come without some measure of resistance, and figuring out how to overcome it will require that she, too, explore new leadership methods and avenues of thought to ensure everyone comes on board.

June 15, 2018 | More

Sheryl Sandberg on Facebook's missteps and what comes next

Sheryl Sandberg on Facebook’s missteps and what comes next

The more they ask “Could we?” the more creative people become. But the more they ask “Should we?” the more ethical they become.

That was the message from Facebook chief operating officer Sheryl Sandberg at MIT’s 2018 commencement ceremony, held June 8 on campus.

Facebook in the past year has faced a series of privacy scandals and ethical questions, most notably when it was reported that consulting firm Cambridge Analytica had mined the personal data of millions of Facebook users and used it to influence voter opinion. Facebook has also been criticized for failing to contain the spread of fake news.

June 15, 2018 | More

Innovating around the box

Innovating around the box

Managers today are told that improving their business incrementally each year is no longer good enough. Rather, to succeed they must disrupt themselves — revolutionize their company and their industry — before a competitor beats them to it.

In a May 16 webinar for MIT Sloan Alumni Online, senior lecturer David Robertson discussed a third way that businesses can grow, taken from his 2017 book, “The Power of Little Ideas: A Low-Risk, High-Reward Approach to Innovation.” Rather than disrupt a business, companies can grow by finding ways to innovate around existing products.

“When you have an existing product, and have an existing market, you shouldn’t be quick to jump away from it and explore disruptive, new innovations,” Robertson said. “That’s prone to failure and is often very expensive and risky. Look to see if you can innovate around it.”

In the webinar, Robertson explains:

· What is the third way?

· How is this different than other approaches to innovation?

· Which approaches are the most important for managers to know?

What is the third way?
Robertson said too often he hears stories about mature companies feeling forced to choose between incremental change and disruption when a third way exists: Innovate around existing products and services. Lego chose this path after facing near disaster.

In the late 1990s, Lego got caught up in the disruptive innovation frenzy that gripped corporate thought. After 15 straight years of 14 percent average annual growth, sales plateaued. Lego became convinced that the brick, whose patents had expired in the 1980s, was becoming a commodity. The company’s executives convinced themselves they had to overhaul their business, move away from their iconic brick, and reinvent the future of play before a competitor did. The result was four years of expensive failures. The company almost went bankrupt.

But Lego learned a lesson: when it went away from the brick, customers had no reason to purchase Lego toys. While it wasn’t sufficient to offer only a box of bricks, it was necessary. When Lego went back to the brick and innovated around it, customers returned to the brand and sales rebounded. (Robertson was the Lego Professor of Innovation and Technology Management at the International Institute for Management Development and wrote “Brick by Brick,” a book about Lego’s success in innovation.)

To pursue this third way, a company must start by defining the product or service it wants to innovate around, then decide its business promise to its customers, then design and deliver those complementary innovations to market.

Lego checked all of those boxes when it introduced Lego Batman in 2006. A major movie followed in 2017. Along with Lego Batman, there were a series of complementary products designed to increase kids’ involvement with the story. There was a comic book, Happy Meal toys, a video game, and an iPhone tie-in. (Open Siri, say “Hey computer,” and see what happens.)

How is this different than other approaches to innovation?
An incremental improvement to current products is a necessary activity for any company, but usually only keeps you abreast of the competition. Disruptive innovations like Uber can change an entire industry. But in between the two is the third way, which any company can pursue. The secret: Build a deep relationship with your customer. Date your customer, and don’t fight your competitor, Robertson said.

Between 2010 to 2015, GoPro practiced this third-way approach and achieved five years of 90 percent average annual sales growth. The company developed not only a rugged, waterproof action camera, but also a smartphone app, a variety of camera mounts, desktop software to turn raw footage into polished movies, and a social media site for customers to share their adventures. By “dating their customer” GoPro was able to understand what they wanted to achieve with their cameras, and provide the complementary products and services to help them.

Sony thought it could knock GoPro off its perch, and developed a better and less expensive rival camera. Yet, it barely dented GoPro’s market share. Why? Sony fought the competition while GoPro was dating the customer. Sony had a better and cheaper camera, but GoPro had a portfolio of complementary products and services that together helped customers capture their adventures.

Which innovation approaches are the most important for managers to know?
There are several types of innovation, Robertson said: incremental improvements, lean-startup, blue-ocean, disruptive, and Robertson’s third-way. Successful companies cycle through these different types of innovation over the years. They may start as blue-ocean innovators, like GoPro, but end up innovating around a product to hold onto their core markets. “Managers need to know all these different types of innovations and practice them,” Robertson said.

But knowing how to innovate around a product or service is especially important, Robertson said, because it can lead to new opportunities. Consider the company behind the Spin Pop electric lollipops. The Spin Pop has a tiny motor that spins a lollipop, adding a new feature to an existing product. The company then developed the SpinBrush, which had a similar motor-and-battery combination to power an inexpensive electric toothbrush (a “blue ocean” innovation). The SpinBrush was acquired by Procter & Gamble for $475 million. Procter & Gamble then used the SpinBrush to innovate around its Crest brand and expand it from a toothpaste brand to an oral care brand. Crest now has an electric toothbrush, floss, white strips, mouthwash, and other products. By innovating around the core toothpaste product, Crest was able to revive sales for the toothpaste, as well as gain revenues from the complementary products.

“Too often we jump away from our existing customers and existing products,” Robertson said. “Innovating around those can be incredibly valuable and open up new opportunities for growth.”

Watch the full webinar below.

June 8, 2018 | More

What made Kate Spade a great entrepreneur

What made Kate Spade a great entrepreneur

When Kate Spade, her name eponymous with the working woman’s handbag, died this month at 55, the news was a blow to the fashion and corporate worlds. Those who studied her career are certain of the entrepreneurial legacy she left behind.

In 1993 Spade was an accessories editor for Mademoiselle magazine when she started her handbag company with husband. She was in a great place in terms of her career, said MIT Sloan senior lecturer in managerial communication Neal Hartman, and she took a risk to start her own handbag line.

Hartman, whose teachings include leadership and working in teams, said Spade was playful and creative at heart, and her brand reflected those qualities.

“I think she had a terrific sense of what women wanted, so she knew her customer base and had a good sense of what they wanted more than what they needed,” Hartman said. “She wasn’t going for the $3,000 bag, but she still wanted something that looked good, that was clearly fashionable.”

She told the New York Times in 1999 that she wanted “a functional bag that was sophisticated and had some style.” In an interview with the Toronto Star, she said she wanted her company “to be like a fashion version of L.L. Bean, never in or out.”

A good leader with a good team
Hartman said the other thing that Spade did to ensure her success was assemble a really good team.

“She had a combination of family and non-relative professionals who helped to move the organization forward and Kate paid close attention to both the U.S. and global operations,” Hartman said. “She looked for the right people who fit with the culture and fostered an environment where people wanted to stay with the company.”

Spade left her company in 2007, after then-Liz Claiborne Inc. bought it for $125 million from the Neiman Marcus Group, the Associated Press reported. The company Coach (now known as Tapestry) bought the brand in 2017 for $2.4 billion.

“Her name immediately you associate with her brand, with her product,” Hartman said. “Essentially everyone looked at her as being very successful. Of course it begs the question of were she still with us and continuing in her work, what would be next, where would it go?”

Building an enduring brand
That’s important to note: the question is what’s next, not will the brand survive. Hartman pointed to fashion designer Gianni Versace’s 1997 death as an example — while there were likely some periods of uncertainty for the fashion house, the brand continues today.

The same could be said of the Kate Spade brand, Hartman said, in part because of the team she built at the beginning of the company.

While she was the icon and spokesperson for the brand, others closely connected with her helped make that brand happen, Hartman said, and despite changing hands several times, the brand has endured.

“It’s a brand that people know, it’s a brand that people respect, and again, it’s classy, it’s bright, it’s fun, it’s colorful, it’s functional, it’s high quality, and it’s affordable,” Hartman said. “You essentially have of all the ingredients of a very successful product line.”

June 6, 2018 | More

Defending hospitals against life-threatening cyberattacks

Defending hospitals against life-threatening cyberattacks

From The Conversation Like any large company, a modern hospital has hundreds – even thousands – of workers using countless computers, smartphones and other electronic devices that are vulnerable to security breaches, data thefts and ransomware attacks. But hospitals are unlike other companies in two important ways. They keep medical records, which are among the most sensitive data about people. And many hospital electronics help keep patients alive, monitoring vital signs, administering medications, and even breathing and pumping blood for those in the most dire conditions. A 2013 data breach at the University of Washington Medicine medical group compromised about 90,000 patients’ records and resulted in a US$750,000 fine from federal regulators. In 2015, the UCLA Health system, which includes a number of hospitals, revealed that attackers accessed a part of its network that handled information for 4.5 million patients. Cyberattacks can interrupt medical devices, close emergency rooms and cancel surgeries. The WannaCry attack, for instance, disrupted a third of the UK’s National … Read More »

The post Defending hospitals against life-threatening cyberattacks – Mohammad S. Jalali appeared first on MIT Sloan Experts.

May 9, 2018 | More

Beepi aims for overhaul of used car industry

Beepi aims for overhaul of used car industry

Alejandro Resnik, MBA ’13, has always been driven to solve problems with innovation. So when he learned firsthand the misery of owning a lemon of a used car, Resnik set out to change the way Americans buy automobiles.

On April 15, 2014, Resnik launched Beepi, an online marketplace that enables customers to buy or sell vehicles from home with free delivery, the support of a certified inspection, and a money back guarantee for buyers. The company has grown quickly in California and last month secured a $60 million funding round to expand across the U.S.

May 6, 2018 | More

Here’s why networking isn’t just about landing your dream job

Here’s why networking isn’t just about landing your dream job

From Fortune At a dinner party a few years ago, Salesforce CRM 2.16% Founder Marc Benioff and Dropbox co-founder Drew Houston got to talking. Their conversation led to a new idea, and that idea led to Salesforce’s Chatter, an enterprise social network, Benioff recalled during an interview I had with him two years ago (for an upcoming book about what causes senior leaders, especially CEOs, to ask the right questions – before someone else does it for them). Their conversation led to a new idea, and that idea led to Salesforce’s Chatter, an enterprise social network. Chatter was not just a result of a chance encounter. At the age of 50, Benioff regularly invites 20- and 30-something year-old entrepreneurs to his house for dinner. It’s in this pursuit of perspectives different than his own that he is able to constantly bring new services and ideas to market. Benioff, who is … Read More »

The post Here’s why networking isn’t just about landing your dream job — Hal Gregersen appeared first on MIT Sloan Experts.

May 2, 2018 | More

Smart Parking Solutions – It’s Not About The Parking

Smart solutions for city parking

Parking and traffic congestion are constant sources of frustration for drivers, merchants, employers and public officials in most cities around the world. It is no surprise that smart parking services are top of mind with public officials, city information technology (IT) and innovation executives when planning smart cities.

April 26, 2018 | More

It’s time to found a new republic

It’s time to found a new republic

From Foreign Policy Most Americans tend to believe that they’ve lived under the same form of government, more or less, since the country was founded in late 1700s. They’re mistaken. It’s true that there have been important continuities. The American conception of what government should and should not do is deeply rooted in clear thinking at the start of the republic; the country has long preferred limited government and effective constraints on capricious executive action. But this persistence of core ideas (and the consistent use of the same buildings in Washington, D.C.) obscures the dramatic changes that have taken place within the governing institutions themselves. In fact, formidable challenges at the end of the 19th century were met by fashioning a transformation so thorough it could effectively be deemed a “Second Republic.” This new republic came with significantly different economic and political rules — and, as a result, enabled the … Read More »

The post It’s time to found a new republic – Daron Acemoglu & Simon Johnson appeared first on MIT Sloan Experts.

April 25, 2018 | More

Fail Better: A Q&A with MIT Sloan’s Anjali Sastry

Fail Better: A Q&A with MIT Sloan’s Anjali Sastry

Failure will happen. It’s what you do with it that counts.

In a new book, Fail Better: Design Smart Mistakes and Succeed Sooner, MIT Sloan Senior Lecturer Anjali Sastry and Kara Penn, MBA ’07, chart a better path both to failure and away from it. It’s about not just acknowledging failure, but also planning for action, experimentation, and iteration to ensure that projects are completed in the best way possible.

April 24, 2018 | More

Engineering

Novel transmitter protects wireless data from hackers

Novel transmitter protects wireless data from hackers

Today, more than 8 billion devices are connected around the world, forming an “internet of things” that includes medical devices, wearables, vehicles, and smart household and city technologies. By 2020, experts estimate that number will rise to more than 20 billion devices, all uploading and sharing data online.

But those devices are vulnerable to hacker attacks that locate, intercept, and overwrite the data, jamming signals and generally wreaking havoc. One method to protect the data is called “frequency hopping,” which sends each data packet, containing thousands of individual bits, on a random, unique radio frequency (RF) channel, so hackers can’t pin down any given packet. Hopping large packets, however, is just slow enough that hackers can still pull off an attack.

Now MIT researchers have developed a novel transmitter that frequency hops each individual 1 or 0 bit of a data packet, every microsecond, which is fast enough to thwart even the quickest hackers.

The transmitter leverages frequency-agile devices called bulk acoustic wave (BAW) resonators and rapidly switches between a wide range of RF channels, sending information for a data bit with each hop. In addition, the researchers incorporated a channel generator that, each microsecond, selects the random channel to send each bit. On top of that, the researchers developed a wireless protocol — different from the protocol used today — to support the ultrafast frequency hopping.

“With the current existing [transmitter] architecture, you wouldn’t be able to hop data bits at that speed with low power,” says Rabia Tugce Yazicigil, a postdoc in the Department of Electrical Engineering and Computer Science and first author on a paper describing the transmitter, which is being presented at the IEEE Radio Frequency Integrated Circuits Symposium. “By developing this protocol and radio frequency architecture together, we offer physical-layer security for connectivity of everything.” Initially, this could mean securing smart meters that read home utilities, control heating, or monitor the grid.

“More seriously, perhaps, the transmitter could help secure medical devices, such as insulin pumps and pacemakers, that could be attacked if a hacker wants to harm someone,” Yazicigil says. “When people start corrupting the messages [of these devices] it starts affecting people’s lives.”

Co-authors on the paper are Anantha P. Chandrakasan, dean of MIT’s School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science (EECS); former MIT postdoc Phillip Nadeau; former MIT undergraduate student Daniel Richman; EECS graduate student Chiraag Juvekar; and visiting research student Kapil Vaidya.

Ultrafast frequency hopping

One particularly sneaky attack on wireless devices is called selective jamming, where a hacker intercepts and corrupts data packets transmitting from a single device but leaves all other nearby devices unscathed. Such targeted attacks are difficult to identify, as they’re often mistaken for poor a wireless link and are difficult to combat with current packet-level frequency-hopping transmitters.

With frequency hopping, a transmitter sends data on various channels, based on a predetermined sequence shared with the receiver. Packet-level frequency hopping sends one data packet at a time, on a single 1-megahertz channel, across a range of 80 channels. A packet takes around 612 microseconds for BLE-type transmitters to send on that channel. But attackers can locate the channel during the first 1 microsecond and then jam the packet.

“Because the packet stays in the channel for long time, and the attacker only needs a microsecond to identify the frequency, the attacker has enough time to overwrite the data in the remainder of packet,” Yazicigil says.

To build their ultrafast frequency-hopping method, the researchers first replaced a crystal oscillator — which vibrates to create an electrical signal — with an oscillator based on a BAW resonator. However, the BAW resonators only cover about 4 to 5 megahertz of frequency channels, falling far short of the 80-megahertz range available in the 2.4-gigahertz band designated for wireless communication. Continuing recent work on BAW resonators — in a 2017 paper co-authored by Chandrakasan, Nadeau, and Yazicigil — the researchers incorporated components that divide an input frequency into multiple frequencies. An additional mixer component combines the divided frequencies with the BAW’s radio frequencies to create a host of new radio frequencies that can span about 80 channels.

Randomizing everything

The next step was randomizing how the data is sent. In traditional modulation schemes, when a transmitter sends data on a channel, that channel will display an offset — a slight deviation in frequency. With BLE modulations, that offset is always a fixed 250 kilohertz for a 1 bit and a fixed -250 kilohertz for a 0 bit. A receiver simply notes the channel’s 250-kilohertz or -250-kilohertz offset as each bit is sent and decodes the corresponding bits.

But that means, if hackers can pinpoint the carrier frequency, they too have access to that information. If hackers can see a 250-kilohertz offset on, say, channel 14, they’ll know that’s an incoming 1 and begin messing with the rest of the data packet.

To combat that, the researchers employed a system that each microsecond generates a pair of separate channels across the 80-channel spectrum. Based on a preshared secret key with the transmitter, the receiver does some calculations to designate one channel to carry a 1 bit and the other to carry a 0 bit. But the channel carrying the desired bit will always display more energy. The receiver then compares the energy in those two channels, notes which one has a higher energy, and decodes for the bit sent on that channel.

For example, by using the preshared key, the receiver will calculate that 1 will be sent on channel 14 and a 0 will be sent on channel 31 for one hop. But the transmitter only wants the receiver to decode a 1. The transmitter will send a 1 on channel 14, and send nothing on channel 31. The receiver sees channel 14 has a higher energy and, knowing that’s a 1-bit channel, decodes a 1. In the next microsecond, the transmitter selects two more random channels for the next bit and repeats the process.

Because the channel selection is quick and random, and there is no fixed frequency offset, a hacker can never tell which bit is going to which channel. “For an attacker, that means they can’t do any better than random guessing, making selective jamming infeasible,” Yazicigil says.

As a final innovation, the researchers integrated two transmitter paths into a time-interleaved architecture. This allows the inactive transmitter to receive the selected next channel, while the active transmitter sends data on the current channel. Then, the workload alternates. Doing so ensures a 1-microsecond frequency-hop rate and, in turn, preserves the 1-megabyte-per-second data rate similar to BLE-type transmitters.

“Most of the current vulnerability [to signal jamming] stems from the fact that transmitters hop slowly and dwell on a channel for several consecutive bits. Bit-level frequency hopping makes it very hard to detect and selectively jam the wireless link,” says Peter Kinget, a professor of electrical engineering and chair of the department at Columbia University. “This innovation was only possible by working across the various layers in the communication stack requiring new circuits, architectures, and protocols. It has the potential to address key security challenges in IoT devices across industries.”

The work was supported by Hong Kong Innovation and Technology Fund, the National Science Foundation, and Texas Instruments. The chip fabrication was supported by TSMC University Shuttle Program.

June 11, 2018 | More

MIT announces leadership of its Quest for Intelligence

MIT announces leadership of its Quest for Intelligence

Antonio Torralba has been named the inaugural director of the MIT Quest for Intelligence, effective immediately, Provost Martin Schmidt announced today in an email to the MIT community.

Launched on February 1 of this year, The Quest is a campus-wide initiative to discover the foundations of intelligence and to drive the development of technological tools that can positively influence virtually every aspect of society.

“The range of questions we aspire to explore through The Quest is simply breathtaking,” says MIT President L. Rafael Reif. “There are moments in the history of science when the tools, the data, and the big questions are perfectly synchronized to achieve major advances. I believe we are in just such a moment, and that we are poised to advance the understanding of intelligence in every sense in a profound way. Antonio is exactly the leader we need to move this effort forward.”

An expert in computer vision, machine learning, and human visual perception, Torralba is a professor of electrical engineering and computer science, the MIT director of the MIT­–IBM Watson AI Lab, and a principal investigator at the Computer Science and Artificial Intelligence Laboratory (CSAIL).

“The Quest is fundamentally a collaboration, so we are excited to watch Antonio build on the success he has already had with the MIT­–IBM Watson AI Lab,” Schmidt wrote. “Along with the vision and insight he shows in his research, he has remarkable talents as a convener of people and as an enabler of connections.”

Given The Quest’s scale and the breadth of its ambition, Schmidt has also established a robust leadership team to work with Torralba in furthering the initiative’s goals.

Aude Oliva, a principal research scientist at CSAIL and the MIT executive director at the MIT–IBM Watson AI Lab, will serve as The Quest’s executive director.

James DiCarlo, the Peter de Florez Professor of Neuroscience, head of the Department of Brain and Cognitive Sciences, and principal investigator at the McGovern Institute, will be director of “The Core.” One of The Quest’s two linked entities, The Core will advance the science and engineering of both human and machine intelligence. Daniela Rus, the Andrew (1956) and Erna Viterbi Professor of Electrical Engineering and Computer Science, and director of CSAIL, will be associate director of The Core.

The Core’s scientific directors will be Josh Tenenbaum, professor of computational cognitive science, a research thrust leader at the Center for Brains, Minds and Machines, and a member of CSAIL; and Leslie Kaelbling, the Panasonic Professor of Computer Science and Engineering and a member of CSAIL. The Core’s founding scientific advisor will be Tomaso Poggio, the Eugene McDermott Professor of Brain and Cognitive Sciences, director of the Center for Brains, Minds and Machines, a member of CSAIL, and principal investigator at the McGovern Institute. Together, the leadership of The Core will bring together teams of researchers to tackle the most ambitious “moonshot” projects focusing on the science and engineering of intelligence.

Nicholas Roy, professor of aeronautics and astronautics and a member of CSAIL, will be the director of The Quest’s second linked entity, “The Bridge.” Dedicated to the application of MIT discoveries in natural and artificial intelligence to all disciplines, The Bridge will host state-of-the-art tools from industry and research labs worldwide. The Bridge’s associate director of strategic initiatives will be Cynthia Breazeal, an associate professor of media arts and sciences at the Media Lab. Roy and Breazeal will work with faculty from across MIT to ensure the discoveries and developments facilitated by The Quest have an impact, both within and beyond academic research.

“I would like to extend my deep appreciation to this new leadership team, and to the many faculty who have helped us get this remarkable initiative off to such a powerful start,” Schmidt wrote. “We look forward to the advances and discoveries that are yet to come as we embark on The Quest.”

June 11, 2018 | More

A better device for measuring electromagnetic radiation

A better device for measuring electromagnetic radiation

Bolometers, devices that monitor electromagnetic radiation through heating of an absorbing material, are used by astronomers and homeowners alike. But most such devices have limited bandwidth and must be operated at ultralow temperatures. Now, researchers say they’ve found a ultrafast yet highly sensitive alternative that can work at room temperature — and may be much less expensive.

The findings, published today in the journal Nature Nanotechnology, could help pave the way toward new kinds of astronomical observatories for long-wavelength emissions, new heat sensors for buildings, and even new kinds of quantum sensing and information processing devices, the multidisciplinary research team says. The group includes recent MIT postdoc Dmitri Efetov, Professor Dirk Englund of MIT’s Department of Electrical Engineering and Computer Science, Kin Chung Fong of Raytheon BBN Technologies, and colleagues from MIT and Columbia University.

“We believe that our work opens the door to new types of efficient bolometers based on low-dimensional materials,” says Englund, the paper’s senior author. He says the new system, based on the heating of electrons in a small piece of a two-dimensional form of carbon called graphene, for the first time combines both high sensitivity and high bandwidth — orders of magnitude greater than that of conventional bolometers — in a single device.

“The new device is very sensitive, and at the same time ultrafast,” having the potential to take readings in just picoseconds (trillionths of a second), says Efetov, now a professor  at ICFO, the Institute of Photonic Sciences in Barcelona, Spain, who is the paper’s lead author. “This combination of properties is unique,” he says.

The new system also can operate at any temperature, he says, unlike current devices that have to be cooled to extremely low temperatures. Although most actual applications of the device would still be done under these ultracold conditions, for some applications, such as thermal sensors for building efficiency, the ability to operate without specialized cooling systems could be a real plus. “This is the first device of this kind that has no limit on temperature,” Efetov says.

The new bolometer they built, and demonstrated under laboratory conditions, can measure the total energy carried by the photons of incoming electromagnetic radiation, whether that radiation is in the form of visible light, radio waves, microwaves, or other parts of the spectrum. That radiation may be coming from distant galaxies, or from the infrared waves of heat escaping from a poorly insulated house.

The device is entirely different from traditional bolometers, which typically use a metal to absorb the radiation and measure the resulting temperature rise. Instead, this team developed a new type of bolometer that relies on heating electrons moving in a small piece of graphene, rather than heating a solid metal. The graphene is coupled to a device called a photonic nanocavity, which serves to amplify the absorption of the radiation, Englund explains.

“Most bolometers rely on the vibrations of atoms in a piece of material, which tends to make their response slow,” he says. In this case, though, “unlike a traditional bolometer, the heated body here is simply the electron gas, which has a very low heat capacity, meaning that even a small energy input due to absorbed photons causes a large temperature swing,” making it easier to make precise measurements of that energy. Although graphene bolometers had previously been demonstrated, this work solves some of the important outstanding challenges, including efficient absorption into the graphene using a nanocavity, and the impedance-matched temperature readout.

The new technology, Englund says, “opens a new window for bolometers with entirely new functionalities that could radically improve thermal imaging, observational astronomy, quantum information, and quantum sensing, among other applications.”

For astronomical observations, the new system could help by filling in some of the remaining wavelength bands that have not yet had practical detectors to make observations, such as the “terahertz gap” of frequencies that are very difficult to pick up with existing systems. “There, our detector could be a state-of-the-art system” for observing these elusive rays, Efetov says. It could be useful for observing the very long-wavelength cosmic background radiation, he says.

Daniel Prober, a professor of applied physics at Yale University who was not involved in this research, says, “This work is a very good project to utilize the many benefits of the ultrathin metal layer, graphene, while cleverly working around the limitations that would otherwise be imposed by its conducting nature.” He adds, “The resulting detector is extremely sensitive for power detection in a challenging region of the spectrum, and is now ready for some exciting applications.”

And Robert Hadfield, a professor of photonics at the University of Glasgow, who also was not involved in this work, says, “There is  huge demand for new high-sensitivity infrared detection technologies. This work by Efetov and co-workers reporting an innovative graphene bolometer integrated in a photonic crystal cavity to achieve high absorption is timely and exciting.”

June 11, 2018 | More

MIT faculty approves new urban science major

MIT faculty approves new urban science major

Urban settlements and technology around the world are co-evolving as flows of population, finance, and politics are reshaping the very identity of cities and nations. Rapid and profound changes are driven by pervasive sensing, the growth and availability of continuous data streams, advanced analytics, interactive communications and social networks, and distributed intelligence. At MIT, urban planners and computer scientists are embracing these exciting new developments.

The rise of autonomous vehicles, sensor-enabled self-management of natural resources, cybersecurity for critical infrastructure, biometric identity, the sharing or gig economy, and continuous public engagement opportunities through social networks and data and visualization are a few of the elements that are converging to shape our places of living.

In recognition of this convergence and the rise of a new discipline bringing together the Institute’s existing programs in urban planning and computer science, the MIT faculty approved a new undergraduate degree, the bachelor of science in urban science and planning with computer science (Course 11-6), at its May 16 meeting.

The new major will jointly reside in and be administered by the Department of Urban Studies and Planning (DUSP) and the Department of Electrical Engineering and Computer Science (EECS).

Combining urban planning and public policy, design and visualization, data analysis, machine learning, and artificial intelligence, pervasive sensor technology, robotics, and other aspects of both computer science and city planning, the program will reflect how urban scientists are making sense of cities and urban data in ways never before imagined — and using what they learn to reshape the world in real-time.

“The new joint major will provide important and unique opportunities for MIT students to engage deeply in developing the knowledge, skills, and attitudes to be more effective scientists, planners, and policy makers,” says Eran Ben-Joseph, head of the Department of Urban Studies and Planning. “It will incorporate STEM education and research with a humanistic attitude, societal impact, social innovation, and policy change — a novel model for decision making to enable systemic positive change and create a better world. This is really unexplored, fertile new ground for research, education, and practice.”

The goal of the program is to train undergraduates in the theory and practice of computer science and urban planning and policy-making including ethics and justice, statistics, data science, geospatial analysis, visualization, robotics, and machine learning.

“The new program offers students an opportunity to investigate some of the most pressing problems and challenges facing urban areas today,” says Asu Ozdaglar, head of the Department of Electrical Engineering and Computer Science. “Its interdisciplinary approach will help them combine technical tools with fundamental skills in urban policy to create innovative strategies and solutions addressing real-world problems with great societal impact.”

Although this field draws on existing disciplines, the combination will shape a unique area of knowledge. Practitioners are neither computer scientists nor urban planners in a conventional sense, but represent new kinds of actors with new sets of tools and methodologies. Already, in areas as diverse as transportation, public health, and cybersecurity, researchers and practitioners at MIT are pioneering work along these lines, demonstrating the potential for collaborative efforts.

“Every now and then, the world puts in front of us new problems that require new tools and forms of knowledge to address them,” says Hashim Sarkis, dean of the School of Architecture and Planning. “The growing challenges that cities are facing today has prompted us to develop this new major in urban science. We are combining the tools of AI and big data with those of urban planning, the social sciences, and policy. We are also mobilizing SA+P’s design capacities to unleash the creative potentials of quantitative intelligence through urban science and other collaborations with Engineering and the other schools at MIT.”

The urban science major proposes a comprehensive pedagogy, adding new material and integrated coursework. A centerpiece of this integration will be the degree’s “urban science synthesis lab” requirement, where high-tech tools will be brought together to solve real-world problems.

“This degree program will broaden our students’ perspectives and deepen their exposure in new and exciting directions,” says Anantha P. Chandrakasan, dean of the School of Engineering. “Just like the 6-14 program that EECS and Economics launched last year, this new course of study will empower and challenge students and researchers to think in new ways and form new connections. The value and relevance of computational thinking just keeps growing.”

The new major will be available to all undergraduates starting in fall 2018.

June 5, 2018 | More

Keeping data fresh for wireless networks

Keeping data fresh for wireless networks

For wireless networks that share time-sensitive information on the fly, it’s not enough to transmit data quickly. That data also need to be fresh. Consider the many sensors in your car. While it may take less than a second for most sensors to transmit a data packet to a central processor, the age of that data may vary, depending on how frequently a sensor is relaying readings.

In an ideal network, these sensors should be able to transmit updates constantly, providing the freshest, most current status for every measurable feature, from tire pressure to the proximity of obstacles. But there’s only so much data that a wireless channel can transmit without completely overwhelming the network.

How, then, can a constantly updating network — of sensors, drones, or data-sharing vehicles — minimize the age of the information that it receives at any moment, while at the same time avoiding data congestion?

Engineers in MIT’s Laboratory for Information and Decision Systems are tackling this question and have come up with a way to provide the freshest possible data for a simple wireless network.

The researchers say their method may be applied to simple networks, such as multiple drones that transmit position coordinates to a single control station, or sensors in an industrial plant that relay status updates to a central monitor. Eventually, the team hopes to tackle even more complex systems, such as networks of vehicles that wirelessly share traffic data.

“If you are exchanging congestion information, you would want that information to be as fresh as possible,” says Eytan Modiano, professor of aeronautics and astronautics and a member of MIT’s Laboratory for Information and Decision Systems. “If it’s dated, you might make the wrong decision. That’s why the age of information is important.”

Modiano and his colleagues presented their method in a paper at IEEE’s International Conference on Computation Communications (Infocom), where it won a Best Paper Award. The paper will appear online in the future. The paper’s lead author is graduate student Igor Kadota; former graduate student Abhishek Sinha is also a co-author.

Keeping it fresh

Traditional networks are designed to maximize the amount of data that they can transmit across channels, and minimize the time it takes for that data to reach its destination. Only recently have researchers considered the age of the information — how fresh or stale information is from the perspective of its recipient.

“I first got excited about this problem, thinking in the context of UAVs — unmanned aerial vehicles that are moving around in an environment, and they need to exchange position information to avoid collisions with one another,” Modiano says. “If they don’t exchange this information often enough, they might collide. So we stepped back and started looking at the fundamental problem of how to minimize age of information in wireless networks.”

In this new paper, Modiano’s team looked for ways to provide the freshest possible data to a simple wireless network. They modeled a basic network, consisting of a single data receiver, such as a central control station, and multiple nodes, such as several data-transmitting drones.

The researchers assumed that only one node can transmit data over a wireless channel at any given time. The question they set out to answer: Which node should transmit data at which time, to ensure that the network receives the freshest possible data, on average, from all nodes?

“We are limited in bandwidth, so we need to be selective about what and when nodes are transmitting,” Modiano says. “We say, how do we minimize age in this simplest of settings? Can we solve this? And we did.”

An optimal age

The team’s solution lies in a simple algorithm that essentially calculates an “index” for each node at any given moment. A node’s index is based on several factors: the age, or freshness of the data that it’s transmitting; the reliability of the channel over which it is communicating; and the overall priority of that node.

“For example, you may have a more expensive drone, or faster drone, and you’d like to have better or more accurate information about that drone. So, you can set that one with a high priority,” Kadota explains.

Nodes with a higher priority, a more reliable channel, and older data, are assigned a higher index, versus nodes that are relatively low in priority, communicating over spottier channels, with fresher data, which are labeled with a lower index.

A node’s index can change from moment to moment. At any given moment, the algorithm directs the node with the highest index to transmit its data to the receiver. In this prioritizing way, the team found that the network is guaranteed to receive the freshest possible data on average, from all nodes, without overloading its wireless channels.

The team calculated a lower bound, meaning an average age of information for the network that is fresher than any algorithm could ever achieve. They found that the team’s algorithm performs very close to this bound, and that it is close to the best that any algorithm could do in terms of providing the freshest possible data for a simple wireless network.

“We came up with a fundamental bound that says, you cannot possibly have a lower age of information than this value ­— no algorithm could be better than this bound — and then we showed that our algorithm came close to that bound,” Modiano says. “So it’s close to optimal.”

The team is planning to test its index scheme on a simple network of radios, in which one radio may serve as a base station, receiving time-sensitive data from several other radios. Modiano’s group is also developing algorithms to optimize the age of information in more complex networks.

“Our future papers will look beyond just one base station, to a network with multiple base stations, and how that interacts,” Modiano says. “And that will hopefully solve a much bigger problem.”

This research was funded, in part, by the National Science Foundation (NSF) and the Army Research Office (ARO).

June 5, 2018 | More

Revolutionizing everyday products with artificial intelligence

Revolutionizing everyday products with artificial intelligence

“Who is Bram Stoker?” Those three words demonstrated the amazing potential of artificial intelligence. It was the answer to a final question in a particularly memorable 2011 episode of Jeopardy!. The three competitors were former champions Brad Rutter and Ken Jennings, and Watson, a super computer developed by IBM. By answering the final question correctly, Watson became the first computer to beat a human on the famous quiz show.

“In a way, Watson winning Jeopardy! seemed unfair to people,” says Jeehwan Kim, the Class ‘47 Career Development Professor and a faculty member of the MIT departments of Mechanical Engineering and Materials Science and Engineering. “At the time, Watson was connected to a super computer the size of a room while the human brain is just a few pounds. But the ability to replicate a human brain’s ability to learn is incredibly difficult.”

Kim specializes in machine learning, which relies on algorithms to teach computers how to learn like a human brain. “Machine learning is cognitive computing,” he explains. “Your computer recognizes things without you telling the computer what it’s looking at.”

Machine learning is one example of artificial intelligence in practice. While the phrase “machine learning” often conjures up science fiction typified in shows like “Westworld” or “Battlestar Galactica,” smart systems and devices are already pervasive in the fabric of our daily lives. Computers and phones use face recognition to unlock. Systems sense and adjust the temperature in our homes. Devices answer questions or play our favorite music on demand. Nearly every major car company has entered the race to develop a safe self-driving car.

For any of these products to work, the software and hardware both have to work in perfect synchrony. Cameras, tactile sensors, radar, and light detection all need to function properly to feed information back to computers. Algorithms need to be designed so these machines can process these sensory data and make decisions based on the highest probability of success.

Kim and the much of the faculty at MIT’s Department of Mechanical Engineering are creating new software that connects with hardware to create intelligent devices. Rather than building the sentient robots romanticized in popular culture, these researchers are working on projects that improve everyday life and make humans safer, more efficient, and better informed.

Making portable devices smarter

Jeehwan Kim holds up sheet of paper. If he and his team are successful, one day the power of a super computer like IBM’s Watson will be shrunk down to the size of one sheet of paper. “We are trying to build an actual physical neural network on a letter paper size,” explains Kim.

To date, most neural networks have been software-based and made using the conventional method known as the Von Neumann computing method. Kim however has been using neuromorphic computing methods.

“Neuromorphic computer means portable AI,” says Kim. “So, you build artificial neurons and synapses on a small-scale wafer.” The result is a so-called ‘brain-on-a-chip.’

Rather than compute information from binary signaling, Kim’s neural network processes information like an analog device. Signals act like artificial neurons and move across thousands of arrays to particular cross points, which function like synapses. With thousands of arrays connected, vast amounts of information could be processed at once. For the first time, a portable piece of equipment could mimic the processing power of the brain.

“The key with this method is you really need to control the artificial synapses well. When you’re talking about thousands of cross points, this poses challenges,” says Kim.

According to Kim, the design and materials that have been used to make these artificial synapses thus far have been less than ideal. The amorphous materials used in neuromorphic chips make it incredibly difficult to control the ions once voltage is applied.

In a Nature Materials study published earlier this year, Kim found that when his team made a chip out of silicon germanium they were able to control the current flowing out of the synapse and reduce variability to 1 percent. With control over how the synapses react to stimuli, it was time to put their chip to the test.

“We envision that if we build up the actual neural network with material we can actually do handwriting recognition,” says Kim. In a computer simulation of their new artificial neural network design, they provided thousands of handwriting samples. Their neural network was able to accurately recognize 95 percent of the samples.

“If you have a camera and an algorithm for the handwriting data set connected to our neural network, you can achieve handwriting recognition,” explains Kim.

While building the physical neural network for handwriting recognition is the next step for Kim’s team, the potential of this new technology goes beyond handwriting recognition. “Shrinking the power of a super computer down to a portable size could revolutionize the products we use,” says Kim. “The potential is limitless – we can integrate this technology in our phones, computers, and robots to make them substantially smarter.”

Making homes smarter

While Kim is working on making our portable products more intelligent, Professor Sanjay Sarma and Research Scientist Josh Siegel hope to integrate smart devices within the biggest product we own: our homes.

One evening, Sarma was in his home when one of his circuit breakers kept going off. This circuit breaker — known as an arc-fault circuit interrupter (AFCI) — was designed to shut off power when an electric arc is detected to prevent fires. While AFCIs are great at preventing fires, in Sarma’s case there didn’t seem to be an issue. “There was no discernible reason for it to keep going off,” recalls Sarma. “It was incredibly distracting.”

AFCIs are notorious for such ‘nuisance trips,’ which disconnect safe objects unnecessarily. Sarma, who also serves as MIT’s vice president for open learning, turned his frustration into opportunity. If he could embed the AFCI with smart technologies and connect it to the ‘internet of things,’ he could teach the circuit breaker to learn when a product is safe or when a product actually poses a fire risk.

“Think of it like a virus scanner,” explains Siegel. “Virus scanners are connected to a system that updates them with new virus definitions over time.” If Sarma and Siegel could embed similar technology into AFCIs, the circuit breakers could detect exactly what product is being plugged in and learn new object definitions over time.

If, for example, a new vacuum cleaner is plugged into the circuit breaker and the power shuts off without reason, the smart AFCI can learn that it’s safe and add it to a list of known safe objects. The AFCI learns these definitions with the aid of a neural network. But, unlike Jeewhan Kim’s physical neural network, this network is software-based.

The neural network is built by gathering thousands of data points during simulations of arcing. Algorithms are then written to help the network assess its environment, recognize patterns, and make decisions based on the probability of achieving the desired outcome. With the help of a $35 microcomputer and a sound card, the team can cheaply integrate this technology into circuit breakers.

As the smart AFCI learns about the devices it encounters, it can simultaneously distribute its knowledge and definitions to every other home using the internet of things.

“Internet of things could just as well be called ‘intelligence of things,” says Sarma. “Smart, local technologies with the aid of the cloud can make our environments adaptive and the user experience seamless.”

Circuit breakers are just one of many ways neural networks can be used to make homes smarter. This kind of technology can control the temperature of your house, detect when there’s an anomaly such as an intrusion or burst pipe, and run diagnostics to see when things are in need of repair.

“We’re developing software for monitoring mechanical systems that’s self-learned,” explains Siegel. “You don’t teach these devices all the rules, you teach them how to learn the rules.”

Making manufacturing and design smarter

Artificial intelligence can not only help improve how users interact with products, devices, and environments. It can also improve the efficiency with which objects are made by optimizing the manufacturing and design process.

“Growth in automation along with complementary technologies including 3-D printing, AI, and machine learning compels us to, in the long run, rethink how we design factories and supply chains,” says Associate Professor A. John Hart.

Hart, who has done extensive research in 3-D printing, sees AI as a way to improve quality assurance in manufacturing. 3-D printers incorporating high-performance sensors, that are capable of analyzing data on the fly, will help accelerate the adoption of 3-D printing for mass production.

“Having 3-D printers that learn how to create parts with fewer defects and inspect parts as they make them will be a really big deal — especially when the products you’re making have critical properties such as medical devices or parts for aircraft engines,” Hart explains.

The very process of designing the structure of these parts can also benefit from intelligent software. Associate Professor Maria Yang has been looking at how designers can use automation tools to design more efficiently. “We call it hybrid intelligence for design,” says Yang. “The goal is to enable effective collaboration between intelligent tools and human designers.”

In a recent study, Yang and graduate student Edward Burnell tested a design tool with varying levels of automation. Participants used the software to pick nodes for a 2-D truss of either a stop sign or a bridge. The tool would then automatically come up with optimized solutions based on intelligent algorithms for where to connect nodes and the width of each part.

“We’re trying to design smart algorithms that fit with the ways designers already think,” says Burnell.

Making robots smarter

If there is anything on MIT’s campus that most closely resembles the futuristic robots of science fiction, it would be Professor Sangbae Kim’s robotic cheetah. The four-legged creature senses its surrounding environment using LIDAR technologies and moves in response to this information. Much like its namesake, it can run and leap over obstacles.

Kim’s primary focus is on navigation. “We are building a very unique system specially designed for dynamic movement of the robot,” explains Kim. “I believe it is going to reshape the interactive robots in the world. You can think of all kinds of applications — medical, health care, factories.”

Kim sees opportunity to eventually connect his research with the physical neural network his colleague Jeewhan Kim is working on. “If you want the cheetah to recognize people, voice, or gestures, you need a lot of learning and processing,” he says. “Jeewhan’s neural network hardware could possibly enable that someday.”

Combining the power of a portable neural network with a robot capable of skillfully navigating its surroundings could open up a new world of possibilities for human and AI interaction. This is just one example of how researchers in mechanical engineering can one-day collaborate to bring AI research to next level.

While we may be decades away from interacting with intelligent robots, artificial intelligence and machine learning has already found its way into our routines. Whether it’s using face and handwriting recognition to protect our information, tapping into the internet of things to keep our homes safe, or helping engineers build and design more efficiently, the benefits of AI technologies are pervasive.

The science fiction fantasy of a world overtaken by robots is far from the truth. “There’s this romantic notion that everything is going to be automatic,” adds Maria Yang. “But I think the reality is you’re going to have tools that will work with people and help make their daily life a bit easier.”

June 1, 2018 | More

Featured video: Engineering joy

Featured video: Engineering joy

MIT senior Isabel “Izzy” Lloyd will graduate this spring with not only a degree in mechanical engineering, but with the pleasure of knowing she accomplished a goal she set for herself as a freshman: to impact those around her in a truly positive way.

Lloyd has worn many hats during her MIT career — from captivating audiences with her a cappella group The Chorallaries, to helping Parkinson’s patients with a device that helps manage tremors, to spreading a simple message of compassion and kindness by spearheading the TMYAD (“Tell Me About Your Day”) campaign. To Lloyd, the MIT experience is as rich in its human interactions and encounters as it is in discoveries in the realms of engineering and technology.

“No question, you come here, you’re going to have great times, you’re going to have bad times,” she says. “But through it all, this community’s got you. And if you don’t believe that, I’m sitting here, right now telling you that I’ve got you… It’s going to be OK.”

Submitted by: Carolyn Blais | Video by: Lillie Paquette | 4 min, 58 sec

May 30, 2018 | More

Engineers design color-changing compression bandage

Engineers design color-changing compression bandage

Compression therapy is a standard form of treatment for patients who suffer from venous ulcers and other conditions in which veins struggle to return blood from the lower extremities. Compression stockings and bandages, wrapped tightly around the affected limb, can help to stimulate blood flow. But there is currently no clear way to gauge whether a bandage is applying an optimal pressure for a given condition.

Now engineers at MIT have developed pressure-sensing photonic fibers that they have woven into a typical compression bandage. As the bandage is stretched, the fibers change color. Using a color chart, a caregiver can stretch a bandage until it matches the color for a desired pressure, before, say, wrapping it around a patient’s leg.

The photonic fibers can then serve as a continuous pressure sensor — if their color changes, caregivers or patients can use the color chart to determine whether and to what degree the bandage needs loosening or tightening.

“Getting the pressure right is critical in treating many medical conditions including venous ulcers, which affect several hundred thousand patients in the U.S. each year,” says Mathias Kolle, assistant professor of mechanical engineering at MIT. “These fibers can provide information about the pressure that the bandage exerts. We can design them so that for a specific desired pressure, the fibers reflect an easily distinguished color.”

Kolle and his colleagues have published their results in the journal Advanced Healthcare Materials. Co-authors from MIT include first author Joseph Sandt, Marie Moudio, and Christian Argenti, along with J. Kenji Clark of the Univeristy of Tokyo, James Hardin of the United States Air Force Research Laboratory, Matthew Carty of Brigham and Women’s Hospital-Harvard Medical School, and Jennifer Lewis of Harvard University.

Natural inspiration

The color of the photonic fibers arises not from any intrinsic pigmentation, but from their carefully designed structural configuration. Each fiber is about 10 times the diameter of a human hair. The researchers fabricated the fiber from ultrathin layers of transparent rubber materials, which they rolled up to create a jelly-roll-type structure. Each layer within the roll is only a few hundred nanometers thick.

In this rolled-up configuration, light reflects off each interface between individual layers. With enough layers of consistent thickness, these reflections interact to strengthen some colors in the visible spectrum, for instance red, while diminishing the brightness of other colors. This makes the fiber appear a certain color, depending on the thickness of the layers within the fiber.

“Structural color is really neat, because you can get brighter, stronger colors than with inks or dyes just by using particular arrangements of transparent materials,” Sandt says. “These colors persist as long as the structure is maintained.”

The fibers’ design relies upon an optical phenomenon known as “interference,” in which light, reflected from a periodic stack of thin, transparent layers, can produce vibrant colors that depend on the stack’s geometric parameters and material composition. Optical interference is what produces colorful swirls in oily puddles and soap bubbles. It’s also what gives peacocks and butterflies their dazzling, shifting shades, as their feathers and wings are made from similarly periodic structures.

“My interest has always been in taking interesting structural elements that lie at the origin of nature’s most dazzling light manipulation strategies, to try recreating and employing them in useful applications,” Kolle says.

A multilayered approach

The team’s approach combines known optical design concepts with soft materials, to create dynamic photonic materials.

While a postdoc at Harvard in the group of Professor Joanna Aizenberg, Kolle was inspired by the work of Pete Vukusic, professor of biophotonics at the University of Exeter in the U.K., on Margaritaria nobilis, a tropical plant that produces extremely shiny blue berries. The fruits’ skin is made up of cells with a periodic cellulose structure, through which light can reflect to give the fruit its signature metallic blue color.

Together, Kolle and Vukusic sought ways to translate the fruit’s photonic architecture into a useful synthetic material. Ultimately, they fashioned multilayered fibers from stretchable materials, and assumed that stretching the fibers would change the individual layers’ thicknesses, enabling them to tune the fibers’ color. The results of these first efforts were published in Advanced Materials in 2013.

When Kolle joined the MIT faculty in the same year, he and his group, including Sandt, improved on the photonic fiber’s design and fabrication. In their current form, the fibers are made from layers of commonly used and widely available transparent rubbers, wrapped around highly stretchable fiber cores. Sandt fabricated each layer using spin-coating, a technique in which a rubber, dissolved into solution, is poured onto a spinning wheel. Excess material is flung off the wheel, leaving a thin, uniform coating, the thickness of which can be determined by the wheel’s speed.

For fiber fabrication, Sandt formed these two layers on top of a water-soluble film on a silicon wafer. He then submerged the wafer, with all three layers, in water to dissolve the water-soluble layer, leaving the two rubbery layers floating on the water’s surface. Finally, he carefully rolled the two transparent layers around a black rubber fiber, to produce the final colorful photonic fiber.­­

Reflecting pressure

The team can tune the thickness of the fibers’ layers to produce any desired color tuning, using standard optical modeling approaches customized for their fiber design.

“If you want a fiber to go from yellow to green, or blue, we can say, ‘This is how we have to lay out the fiber to give us this kind of [color] trajectory,’” Kolle says. “This is powerful because you might want to have something that reflects red to show a dangerously high strain, or green for ‘ok.’ We have that capacity.”

The team fabricated color-changing fibers with a tailored, strain-dependent color variation using the theoretical model, and then stitched them along the length of a conventional compression bandage, which they previously characterized to determine the pressure that the bandage generates when it’s stretched by a certain amount.

The team used the relationship between bandage stretch and pressure, and the correlation between fiber color and strain, to draw up a color chart, matching a fiber’s color (produced by a certain amount of stretching) to the pressure that is generated by the bandage.

To test the bandage’s effectiveness, Sandt and Moudio enlisted over a dozen student volunteers, who worked in pairs to apply three different compression bandages to each other’s legs: a plain bandage, a bandage threaded with photonic fibers, and a commercially-available bandage printed with rectangular patterns. This bandage is designed so that when it is applying an optimal pressure, users should see that the rectangles become squares.

Overall, the bandage woven with photonic fibers gave the clearest pressure feedback. Students were able to interpret the color of the fibers, and based on the color chart, apply a corresponding optimal pressure more accurately than either of the other bandages.

The researchers are now looking for ways to scale up the fiber fabrication process. Currently, they are able to make fibers that are several inches long. Ideally, they would like to produce meters or even kilometers of such fibers at a time.

“Currently, the fibers are costly, mostly because of the labor that goes into making them,” Kolle says. “The materials themselves are not worth much. If we could reel out kilometers of these fibers with relatively little work, then they would be dirt cheap.”

Then, such fibers could be threaded into bandages, along with textiles such as athletic apparel and shoes as color indicators for, say, muscle strain during workouts. Kolle envisions that they may also be used as remotely readable strain gauges for infrastructure and machinery.

“Of course, they could also be a scientific tool that could be used in a broader context, which we want to explore,” Kolle says.

This research was supported, in part, by the National Science Foundation and by the MIT Department of Mechanical Engineering.

May 29, 2018 | More

J-WAFS awards over $1.3 million in fourth round of seed grant funding

J-WAFS awards over $1.3 million in fourth round of seed grant funding

Today, the Abdul Latif Jameel World Water and Food Security Lab (J-WAFS) at MIT announced the award of over $1.3 million in research funding through its seed grant program, now in its fourth year. These grants, which are available to the MIT community, are the cornerstone of MIT’s Institute-wide effort to catalyze solutions-oriented research in water and food systems that target the safety and resilience of the world’s vital resources.

This year, seven new projects led by eleven faculty PIs across six MIT departments will be funded with two-year grants of up to $200,000, overhead free. The winning projects include a silk-based food safety sensor; research into climate vulnerability and resilience in agriculture using biological engineering as well as crop modeling and sensors; an archeological and materials engineering approach to understanding fertile tropical soils; and three different strategies for water purification and management.

The reach of the J-WAFS’s seed grants across the Institute is wide and reflects how faculty from all schools at MIT are invested in addressing the critical challenges that face our most essential global resources. This J-WAFS call for seed research proposals attracted 54 principal investigators, nearly twice the number that submitted proposals in 2017. What is more, 38 of these PIs were proposing to J-WAFS for the first time. “The J-WAFS seed grants continue to stimulate new thinking about how to address some of our most serious water and food problems, whether by new junior faculty at MIT or senior professors,” noted Renee Robins, executive director of J-WAFS.

Faculty from six departments were funded under this year’s awards, including the departments of Civil and Environmental Engineering, Chemical Engineering, Earth, Atmospheric and Planetary Sciences, Materials Science and Engineering, Electrical Engineering and Computer Science, and Mechanical Engineering.

New approaches to ensure safe drinking water

The problem of arsenic contamination in water occurs throughout the globe, and is particularly extreme in South Asia, where over 100 million people in Bangladesh, Nepal, India, Cambodia, Pakistan, Vietnam, and Myanmar experience daily exposure to dangerous concentrations of arsenic that occurs naturally in groundwater. Yet the poorly understood behavior of arsenic in groundwater makes it challenging to identify safe sources of drinking water. Charlie Harvey, professor of civil and environmental engineering, has conducted extensive field research on  this issue. With J-WAFS funding, Harvey will consolidate data and develop models to identify and disseminate more effective groundwater management strategies that take into account how and where dangerous concentrations of arsenic exist.

Julia Ortony, the Finmeccanica Career Development Assistant Professor of Engineering in the Department of Materials Science and Engineering, will be taking a different approach to arsenic contamination. Her lab develops molecular nanomaterials for environmental contaminant remediation. A J-WAFS seed grant will support her development of a robust, high surface-area material made of small molecules that can be designed to sequester arsenic from drinking water.

Boron is an essential micronutrient for both plants and animals, but becomes toxic at higher concentrations. However, due to its small molecular size and un-charged chemical structure, it is particularly difficult to remove with standard water purification technologies. Zachary P. Smith, the Joseph R. Mares Career Development Professor in the Department of Chemical Engineering, is taking advantage of advancements in molecular level synthesis of metal-organic framework (MOF) materials to open the door to a new generation of highly selective membranes for water purification and desalination that can remove boron. Leveraging techniques and expertise at the interface of inorganic chemistry, materials science, and chemical engineering, Smith aims to achieve technical breakthroughs in water purification with this J-WAFS funding.

Improving understanding of soil and climate impacts on agriculture for improved crop production

Climate change is bringing temperature and precipitation changes that will increasingly stress the crops our global food system depends on, and these changes will affect regions of the world differently. Breeding plants for increased resilience to stressors such as drought is one solution, but traditional breeding approaches can be extremely slow. In part, this slowness results from the complexity of plants’ response to environmental stress. David Des Marais, assistant professor in civil and environmental engineering, and Caroline Uhler, assistant professor of electrical engineering and computer science want to better understand this complexity in order to improve future practices to breed plants for stress tolerance. By combining Des Marais’ expertise in plant-environment interaction and sustainable agriculture with Uhler’s statistical approaches to studying networks, the team will develop new analytical tools to understand the structure and dynamics of the gene regulatory networks that plants use to perceive — and respond to — changes in the environment.

Dara Entekhabi, the Bacardi and Stockholm Water Foundations Professor in the departments of Civil and Environmental Engineering and Earth, Atmospheric and Planetary Sciences, is taking another approach to understanding the impacts of climate on agricultural production. The project, in collaboration with research scientist Sarah Fletcher from MIT’s Institute for Data, Systems, and Society, is focused on Sub-Saharan Africa. This region is experiencing very high population growth, and with its largely rain-fed agriculture is particularly vulnerable to anticipated temperature and precipitation changes brought about by climate change. The MIT research team is leading an academic-industry partnership that seeks to understand how crop production in the region responds to year-to-year variation in precipitation in order to assess the future of food security in Africa. They will collaborate with Radiant Earth, a startup that uses a geospatial imagery technology platform to capture and understand the impact of social challenges in the developing world, to develop a better understanding of the impact of climate on food security in Sub-Saharan Africa.

A very different approach to improving agricultural productivity involves better understanding and managing soil fertility. In another innovative multidisciplinary project, three PIs whose expertise spans geoscience, archaeology, and materials engineering will collaborate to improve our understanding of extensive deposits of rich soils known as terra preta (“dark earth” in Portuguese) in the Amazon Basin that pre-Columbian societies created and cultivated between 500 and about 8,700 years ago. Many tropical soils are nutrient-poor and contain little organic carbon, but terra preta is so carbon-rich and fertile that it is still farmed (and destructively mined) today. Researchers are now attempting to reproduce terra preta as part of a strategy for sustainable tropical agriculture and carbon sequestration. A team consisting of Taylor Perron, associate professor in the Department of Earth, Atmospheric and Planetary Sciences, and Dorothy Hosler and Heather Lechtman, both professors of archaeology and ancient technology in the Department of Materials Science and Engineering, aims to inform agricultural practices in tropical developing nations by investigating how the rivers of the Amazon region influenced terra preta formation.

Using edible food safety sensors to reduce food waste and disease

While strategies to improve agricultural productivity are critical to global food security, minimizing food loss from farm to table is also considered to be necessary if we are to meet our future food needs. Cost-effective and easy-to-use methods of detecting food spoilage along the food supply chain can help. A. John Hart, associate professor of mechanical engineering, and Benedetto Marelli, the Paul M. Cook Career Development Professor in the Department of Civil and Environmental Engineering, have teamed up to find a solution. J-WAFS seed funding is supporting the development of a silk-based food safety sensor, visible to the naked eye, which can change color based on its interaction with common food pathogens. The sensor will take the form of printable inks that are stable under extreme temperatures and also edible. Their aim is to print on food packaging as well as directly on food in order to enable point-of-use detection of contamination and food spoilage for meat and dairy products.

With these seven newly funded projects, J-WAFS will have funded 30 total seed research projects since its founding in 2014. J-WAFS’ director John Lienhard states that “investing in research results in creative innovations in food and water that will enable a sustainable future.  Further, these seed grants have repeatedly been leveraged by their recipients to develop significant follow-on programs, that further multiply the impact.”

2018 J-WAFS Seed Grant recipients and their projects:

Novel systems biology tools for improving crop tolerance to abiotic stressors.” PIs: David Des Marais, assistant professor in the Department of Civil and Environmental Engineering, and Caroline Uhler, the Henry L. and Grace Doherty Assistant Professor in the Department of Electrical Engineering and Computer Science and Institute for Data, Systems and Society.

Assessing Climate Vulnerability of West African Food Security using Remote Sensing.” PIs: Dara Entekhabi, the Bacardi and Stockholm Water Foundations Professor in the Department of Civil and Environmental Engineering.

Printed Silk-Based Colorimetric Sensors for Food Spoilage Prevention and Supply Chain Authentication.” PIs: A. John Hart, associate professor in the Department of Mechanical Engineering, and Benedetto Marelli, the Paul M. Cook Career Development Professor in the Department of Civil and Environmental Engineering.

What controls Arsenic Contamination in South Asia? Making Sense of Two-Decades of Disjointed Data.” PI: Charles Harvey, professor in the Department of Civil and Environmental Engineering.

Supermolecular nanostructure gels for chelation of arsenic from drinking water.” PI: Julia Ortony, the Finmeccanica Career Development Professor in the Department of Materials Science and Engineering.

Anthropogenic Soils of the Amazon: Origins, Extent, and Implications for Sustainable Tropical Agriculture.” PIs: J. Taylor Perron, associate professor of geology in the Department of Earth, Planetary and Atmospheric Sciences; Dorothy Hosler, professor of archaeology and ancient technology in the Department of Materials Science and Engineering; and Heather Lechtman, professor of archaeology and ancient technology in the Department of Materials Science and Engineering.

Purifying Water from Boron Contamination with Highly Selective Metal-Organic Framework (MOF) Membranes.” PI: Zachary Smith, the Joseph R. Mares Career Development Professor in the Department of Chemical Engineering.

May 25, 2018 | More

Ingestible “bacteria on a chip” could help diagnose disease

Ingestible “bacteria on a chip” could help diagnose disease

MIT researchers have built an ingestible sensor equipped with genetically engineered bacteria that can diagnose bleeding in the stomach or other gastrointestinal problems.

This “bacteria-on-a-chip” approach combines sensors made from living cells with ultra-low-power electronics that convert the bacterial response into a wireless signal that can be read by a smartphone.

“By combining engineered biological sensors together with low-power wireless electronics, we can detect biological signals in the body and in near real-time, enabling new diagnostic capabilities for human health applications,” says Timothy Lu, an MIT associate professor of electrical engineering and computer science and of biological engineering.

In the new study, appearing in the May 24 online edition of Science, the researchers created sensors that respond to heme, a component of blood, and showed that they work in pigs. They also designed sensors that can respond to a molecule that is a marker of inflammation.

Lu and Anantha Chandrakasan, dean of MIT’s School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science, are the senior authors of the study. The lead authors are graduate student Mark Mimee and former MIT postdoc Phillip Nadeau.

Wireless communication

In the past decade, synthetic biologists have made great strides in engineering bacteria to respond to stimuli such as environmental pollutants or markers of disease. These bacteria can be designed to produce outputs such as light when they detect the target stimulus, but specialized lab equipment is usually required to measure this response.

To make these bacteria more useful for real-world applications, the MIT team decided to combine them with an electronic chip that could translate the bacterial response into a wireless signal.

“Our idea was to package bacterial cells inside a device,” Nadeau says. “The cells would be trapped and go along for the ride as the device passes through the stomach.”

For their initial demonstration, the researchers focused on bleeding in the GI tract. They engineered a probiotic strain of E. coli to express a genetic circuit that causes the bacteria to emit light when they encounter heme.

They placed the bacteria into four wells on their custom-designed sensor, covered by a semipermeable membrane that allows small molecules from the surrounding environment to diffuse through. Underneath each well is a phototransistor that can measure the amount of light produced by the bacterial cells and relay the information to a microprocessor that sends a wireless signal to a nearby computer or smartphone. The researchers also built an Android app that can be used to analyze the data.

The sensor, which is a cylinder about 1.5 inches long, requires about 13 microwatts of power. The researchers equipped the sensor with a 2.7-volt battery, which they estimate could power the device for about 1.5 months of continuous use. They say it could also be powered by a voltaic cell sustained by acidic fluids in the stomach, using technology that Nadeau and Chandrakasan have previously developed.

“The focus of this work is on system design and integration to combine the power of bacterial sensing with ultra-low-power circuits to realize important health sensing applications,” Chandrakasan says.

Diagnosing disease

The researchers tested the ingestible sensor in pigs and showed that it could correctly determine whether any blood was present in the stomach. They anticipate that this type of sensor could be either deployed for one-time use or designed to remain the digestive tract for several days or weeks, sending continuous signals.

Currently, if patients are suspected to be bleeding from a gastric ulcer, they have to undergo an endoscopy to diagnose the problem, which often requires the patient to be sedated.

“The goal with this sensor is that you would be able to circumvent an unnecessary procedure by just ingesting the capsule, and within a relatively short period of time you would know whether or not there was a bleeding event,” Mimee says.

To help move the technology toward patient use, the researchers plan to reduce the size of the sensor and to study how long the bacteria cells can survive in the digestive tract. They also hope to develop sensors for gastrointestinal conditions other than bleeding.

In the Science paper, the researchers adapted previously described sensors for two other molecules, which they have not yet tested in animals. One of the sensors detects a sulfur-containing ion called thiosulfate, which is linked to inflammation and could be used to monitor patients with Crohn’s disease or other inflammatory conditions. The other detects a bacterial signaling molecule called AHL, which can serve as a marker for gastrointestinal infections because different types of bacteria produce slightly different versions of the molecule.

“Most of the work we did in the paper was related to blood, but conceivably you could engineer bacteria to sense anything and produce light in response to that,” Mimee says. “Anyone who is trying to engineer bacteria to sense a molecule related to disease could slot it into one of those wells, and it would be ready to go.”

The researchers say the sensors could also be designed to carry multiple strains of bacteria, allowing them to diagnose a variety of conditions.

“Right now, we have four detection sites, but if you could extend it to 16 or 256, then you could have multiple different types of cells and be able to read them all out in parallel, enabling more high-throughput screening,” Nadeau says.

The research was funded by Texas Instruments, the Hong Kong Innovation and Technology Fund, the Office of Naval Research, the National Science Foundation, the Center for Microbiome Informatics and Therapeutics, Brigham and Women’s Hospital, a Qualcomm Innovation Fellowship, and the Natural Sciences and Engineering Council of Canada. Chip fabrication was provided by the TSMC University Shuttle Program.

May 24, 2018 | More