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Thursday, June 30th, 2016
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| 12:00a |
“It’s okay if it breaks and blows up” A robot that can throw fire and saws into its opponents with a spinning blade; a 250-pound bot that can damage and throw competitors with a steel drum powered by its 100-horsepower motor; and a robot with two sets of arms to grab and hoist other machines: These are some of the robots developed by MIT-affiliated teams selected to compete in the second season of ABC’s “BattleBots.”
Throughout the 2016 spring semester, four teams of MIT students, research staff, and alumni worked to design, construct, and test combat robots for the “BattleBots” competition, a reboot of the Comedy Central classic that pits homemade combat robots against one another in an elimination-style tournament.
For the MIT participants, competing in “BattleBots” was an opportunity to not only design and build the combat robot of their dreams, but also to apply and test engineering concepts in an exhilarating, hands-on manner. In addition to their academic coursework and extracurricular activities, the competitors dedicated countless hours to building their robots from the ground up, work that provided them with a diverse range of engineering experiences.
“One of the more fun things about ‘BattleBots’ and combat robotics in general is you get to do head-to-head engineering with other people and you get to do it in a pretty low-stress environment. It’s okay if it breaks and blows up because that’s what it’s supposed to do,” says Rebecca Li, a rising senior who led the development of a robot named The Dentist, which features a spinning drum powered by a 100-horsepower motor. “I think that’s what makes it a great hobby sport.”
Landon Carter, a rising senior majoring in mechanical engineering and computer science who worked with Li on The Dentist, said that in addition to the complex mechanical and electrical design challenges the team faced, he learned “a ton of materials science. ‘BattleBots’ at this stage has reached a level of optimization where you really have to care about which materials you are using and in what applications.”
For MIT research engineer Dane Kouttron, who co-led a team called Road Rash, “BattleBots” provided an opportunity to explore the engineering challenge of using giant roller coaster motors and a nonrotary propulsion system to power a robot.
The high level of participation by MIT affiliates in “BattleBots” is an example of MIT’s thriving maker culture, according to Dawn Wendell ’04, SM ’06, PhD ’11, a senior lecturer in the Department of Mechanical Engineering who participated in “BattleBots” as an MIT student during the original Comedy Central show.
Wendell, who served as the faculty advisor for two of the teams, notes that competing in “BattleBots” provides an opportunity for participants to go from concept “all the way through to implementation, [ultimately] having a physical object in front of them that they had the idea for and that they created. This is a really perfect example of MIT’s motto, which is ‘mens et manus,’ or ‘mind and hand.’”
MIT’s ability to field four teams stems in large part from the many makerspaces on campus where students can build, tinker, and experiment on projects outside the scope of their academic activities. “BattleBots” participants used a variety of these makerspaces to construct their robots, including the Department of Mechanical Engineering’s MakerWorks space, the MIT Electronics Research Society (MITERS) space, and the Edgerton Center Area 51 CNC Shop. Participants say they feel fortunate to have such resources on campus to support their efforts.
“It’s important to have these spaces that are flexible for applications beyond their intended usage,” says Charles Guan ’11. Guan led the Equals Zero Robotics team, which designed their robot, Overhaul, with an upper and lower set of arms so that the robot could grasp and hoist opponents. “Having an unofficial base of operations for a lot of student activities is a source where we get a lot of MIT’s innovation.”
In addition to their academic coursework and other activities, many of the student competitors also serve as mentors for the MakerWorks and MITERS spaces. Lucy Du ’16 — a member of LiMITless Robotics, which built a robot dubbed SawBlaze that corrals and cuts other robots with the spinning saw on its arm and throws green fire at its competitors — observes that having a place that is easily accessible to students, such as MakerWorks, can help encourage even more students to build and create in their free time.
“I think that MakerWorks has really lowered the activation energy for people who really want to make stuff but have a little bit of a hard time getting there,” says Du.
The shared spaces where many “BattleBots” participants built their machines also helped foster a spirit of camaraderie between the teams. Despite the fact that they were building separate robots, the four MIT-affiliated teams frequently collaborated and assisted one another with any roadblocks they ran into during their design and building process.
“It was really nice sharing space on the weekends,” says Du. “We would all be staying really late, but we would notice that all the other teams were here late as well.”
Li recalls how during the competition she frequently ran over to another team’s pit for a spare part or assistance, which she says was always readily provided. The collaborative nature of the event “reinforced that this is a community of people. It’s a competition, but it’s also fun at the same time and everyone also wants to see everyone else succeed,” says Li.
MIT’s strong presence at this year’s competition is in keeping with the Institute’s long history of participation in “BattleBots.” MIT fielded teams during the competition’s initial run on Comedy Central from 2000-2002, and students participated in the follow-up, nontelevised events that occurred during the ensuing years. When “BattleBots” returned to television on ABC last year, a team of MIT affiliates, students, and alumni participated in the competition. That team, which included many of the individuals competing in the current season, then splintered into several teams this year so that participants could have an opportunity to build a variety of robots and explore different engineering principles.
Wendell notes that it’s great to see MIT students participating in “BattleBots” who may have been inspired by the first run of the show to pursue a career in engineering. The show’s ability to excite audiences about robotics and engineering is one of her favorite aspects of the competition.
“It’s really fantastic to see that by having “BattleBots” back on TV it has gotten the general public really excited about engineering and robots. And it’s cool to be able to tell my students, who normally see me in a very official role or who see me in the classroom, that I was once in their shoes,” says Wendell. “I was an undergrad and I was building robots and hoping that they would work, but learning a lot in the experiences where they didn’t work as well as I had hoped. And that is a really acceptable and really awesome way to learn.” | | 12:00a |
Wireless, wearable toxic-gas detector MIT researchers have developed low-cost chemical sensors, made from chemically altered carbon nanotubes, that enable smartphones or other wireless devices to detect trace amounts of toxic gases.
Using the sensors, the researchers hope to design lightweight, inexpensive radio-frequency identification (RFID) badges to be used for personal safety and security. Such badges could be worn by soldiers on the battlefield to rapidly detect the presence of chemical weapons — such as nerve gas or choking agents — and by people who work around hazardous chemicals prone to leakage.
“Soldiers have all this extra equipment that ends up weighing way too much and they can’t sustain it,” says Timothy Swager, the John D. MacArthur Professor of Chemistry and lead author on a paper describing the sensors that was published in the Journal of the American Chemical Society. “We have something that would weigh less than a credit card. And [soldiers] already have wireless technologies with them, so it’s something that can be readily integrated into a soldier’s uniform that can give them a protective capacity.”
The sensor is a circuit loaded with carbon nanotubes, which are normally highly conductive but have been wrapped in an insulating material that keeps them in a highly resistive state. When exposed to certain toxic gases, the insulating material breaks apart, and the nanotubes become significantly more conductive. This sends a signal that’s readable by a smartphone with near-field communication (NFC) technology, which allows devices to transmit data over short distances.
The sensors are sensitive enough to detect less than 10 parts per million of target toxic gases in about five seconds. “We are matching what you could do with benchtop laboratory equipment, such as gas chromatographs and spectrometers, that is far more expensive and requires skilled operators to use,” Swager says.
Moreover, the sensors each cost about a nickel to make; roughly 4 million can be made from about 1 gram of the carbon nanotube materials. “You really can’t make anything cheaper,” Swager says. “That’s a way of getting distributed sensing into many people’s hands.”
The paper’s other co-authors are from Swager’s lab: Shinsuke Ishihara, a postdoc who is also a member of the International Center for Materials Nanoarchitectonics at the National Institute for Materials Science, in Japan; and PhD students Joseph Azzarelli and Markrete Krikorian.
Wrapping nanotubes
In recent years, Swager’s lab has developed other inexpensive, wireless sensors, called chemiresistors, that have detected spoiled meat and the ripeness of fruit, among other things. All are designed similarly, with carbon nanotubes that are chemically modified, so their ability to carry an electric current changes when exposed to a target chemical.
This time, the researchers designed sensors highly sensitive to “electrophilic,” or electron-loving, chemical substances, which are often toxic and used for chemical weapons.
To do so, they created a new type of metallo-supramolecular polymer, a material made of metals binding to polymer chains. The polymer acts as an insulation, wrapping around each of the sensor’s tens of thousands of single-walled carbon nanotubes, separating them and keeping them highly resistant to electricity. But electrophilic substances trigger the polymer to disassemble, allowing the carbon nanotubes to once again come together, which leads to an increase in conductivity.
In their study, the researchers drop-cast the nanotube/polymer material onto gold electrodes, and exposed the electrodes to diethyl chlorophosphate, a skin irritant and reactive simulant of nerve gas. Using a device that measures electric current, they observed a 2,000 percent increase in electrical conductivity after five seconds of exposure. Similar conductivity increases were observed for trace amounts of numerous other electrophilic substances, such as thionyl chloride (SOCl2), a reactive simulant in choking agents. Conductivity was significantly lower in response to common volatile organic compounds, and exposure to most nontarget chemicals actually increased resistivity.
Creating the polymer was a delicate balancing act but critical to the design, Swager says. As a polymer, the material needs to hold the carbon nanotubes apart. But as it disassembles, its individual monomers need to interact more weakly, letting the nanotubes regroup. “We hit this sweet spot where it only works when it’s all hooked together,” Swager says.
Resistance is readable
To build their wireless system, the researchers created an NFC tag that turns on when its electrical resistance dips below a certain threshold.
Smartphones send out short pulses of electromagnetic fields that resonate with an NFC tag at radio frequency, inducing an electric current, which relays information to the phone. But smartphones can’t resonate with tags that have a resistance higher than 1 ohm.
The researchers applied their nanotube/polymer material to the NFC tag’s antenna. When exposed to 10 parts per million of SOCl2 for five seconds, the material’s resistance dropped to the point that the smartphone could ping the tag. Basically, it’s an “on/off indicator” to determine if toxic gas is present, Swager says.
According to the researchers, such a wireless system could be used to detect leaks in Li-SOCl2 (lithium thionyl chloride) batteries, which are used in medical instruments, fire alarms, and military systems.
Alexander Star, a professor of chemistry and bioengineering and clinical and translational science at the University of Pittsburgh, says the researchers’ design for a wireless sensor (or dosimeter) for electrophilic substances could improve soldier safety.
“The authors were able to synthesize a [carbon nanotube] composite sensitive to … a class of chemicals of high interest for sensing,” Star says. “This type of device architecture is important for real-life application, due to the fact that a chemical weapon dosimeter worn by military and security personnel requires rapid reading.”
The next step, Swager says, is to test the sensors on live chemical agents, outside of the lab, which are more dispersed and harder to detect, especially at trace levels. In the future, there’s also hope for developing a mobile app that could make more sophisticated measurements of the signal strength of an NFC tag: Differences in the signal will mean higher or lower concentrations of a toxic gas. “But creating new cell phone apps is a little beyond us right now,” Swager says. “We’re chemists.”
The work was supported by the National Science Foundation and the Japan Society for the Promotion of Science. | | 1:59p |
Scientists observe first signs of healing in the Antarctic ozone layer Scientists at MIT and elsewhere have identified the “first fingerprints of healing” of the Antarctic ozone layer, published today in the journal Science.
The team found that the September ozone hole has shrunk by more than 4 million square kilometers — about half the area of the contiguous United States — since 2000, when ozone depletion was at its peak. The team also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.
The authors used “fingerprints” of the ozone changes with season and altitude to attribute the ozone’s recovery to the continuing decline of atmospheric chlorine originating from chlorofluorocarbons (CFCs). These chemical compounds were once emitted by dry cleaning processes, old refrigerators, and aerosols such as hairspray. In 1987, virtually every country in the world signed on to the Montreal Protocol in a concerted effort to ban the use of CFCs and repair the ozone hole.
“We can now be confident that the things we’ve done have put the planet on a path to heal,” says lead author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT. “Which is pretty good for us, isn’t it? Aren’t we amazing humans, that we did something that created a situation that we decided collectively, as a world, ‘Let’s get rid of these molecules’? We got rid of them, and now we’re seeing the planet respond.”
Solomon’s co-authors include Diane Ivy, research scientist in the Department of Earth, Atmospheric and Planetary Sciences, along with researchers at the National Center for Atmospheric Research in Boulder, Colorado, and the University of Leeds in the U.K.
Signs before spring
The ozone hole was first discovered using ground-based data that began in the 1950s. Around the mid-1980s, scientists from the British Antarctic survey noticed that the October total ozone was dropping. From then on, scientists worldwide typically tracked ozone depletion using October measurements of Antarctic ozone.
Ozone is sensitive not just to chlorine, but also to temperature and sunlight. Chlorine eats away at ozone, but only if light is present and if the atmosphere is cold enough to create polar stratospheric clouds on which chlorine chemistry can occur — a relationship that Solomon was first to characterize in 1986. Measurements have shown that ozone depletion starts each year in late August, as Antarctica emerges from its dark winter, and the hole is fully formed by early October.
Solomon and her colleagues believed they would get a clearer picture of chlorine’s effects by looking earlier in the year, at ozone levels in September, when cold winter temperatures still prevail and the ozone hole is opening up. The team showed that as the chlorine has decreased, the rate at which the hole opens up in September has slowed down.
“I think people, myself included, had been too focused on October, because that’s when the ozone hole is enormous, in its full glory,” Solomon says. “But October is also subject to the slings and arrows of other things that vary, like slight changes in meteorology. September is a better time to look because chlorine chemistry is firmly in control of the rate at which the hole forms at that time of year. That point hasn’t really been made strongly in the past.”
A healing trend
The researchers tracked the yearly opening of the Antarctic ozone hole in the month of September, from 2000 to 2015. They analyzed ozone measurements taken from weather balloons and satellites, as well as satellite measurements of sulfur dioxide emitted by volcanoes, which can also enhance ozone depletion. And, they tracked meteorological changes, such as temperature and wind, which can shift the ozone hole back and forth.
They then compared their yearly September ozone measurements with model simulations that predict ozone levels based on the amount of chlorine that scientists have estimated to be present in the atmosphere from year to year. The researchers found that the ozone hole has declined compared to its peak size in 2000, shrinking by more than 4 million square kilometers by 2015. They further found that this decline matched the model’s predictions, and that more than half the shrinkage was due solely to the reduction in atmospheric chlorine.
“It’s been interesting to think about this in a different month, and looking in September was a novel way,” Ivy says. “It showed we can actually see a chemical fingerprint, which is sensitive to the levels of chlorine, finally emerging as a sign of recovery.”
The team did observe an important outlier in the trend: In 2015, the ozone hole reached a record size, despite the fact that atmospheric chlorine continued to drop. In response, scientists had questioned whether any healing could be determined. Going through the data, however, Solomon and her colleagues realized that the 2015 spike in ozone depletion was due primarily to the eruption of the Chilean volcano Calbuco. Volcanoes don’t inject significant chlorine into the stratosphere but they do increase small particles, which increase the amount of polar stratospheric clouds with which the human-made chlorine reacts.
“Why I like this paper so much is, nature threw us a curveball in 2015,” says Ross Salawitch, professor of chemistry and biochemistry at the University of Maryland. “People thought we set a record for the depth of the ozone hole in October 2015. The Solomon paper explains it was due to a specific volcanic eruption. So without this paper, if all we had was the data, we would be scratching our heads — what was going on in 2015?”
As chlorine levels continue to dissipate from the atmosphere, Solomon sees no reason why, barring future volcanic eruptions, the ozone hole shouldn’t shrink and eventually close permanently by midcentury.
“What’s exciting for me personally is, this brings so much of my own work over 30 years full circle,” says Solomon, whose research into chlorine and ozone spurred the Montreal Protocol. “Science was helpful in showing the path, diplomats and countries and industry were incredibly able in charting a pathway out of these molecules, and now we’ve actually seen the planet starting to get better. It’s a wonderful thing.”
This research was supported, in part, by the National Science Foundation and the U.S. Department of Energy. |
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