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Given that water is 1,000 times denser than air, moving through those two mediums requires very different mechanics—or so one might assume. Yet birds like gulls and puffins can plunge into the sea, swim underwater, and leap back into the air to fly away. And now engineers at MIT and EPFL in Lausanne, Switzerland, have designed a robot that can do likewise. 

The “flapping-wing aerial-aquatic vehicle,” or FAAV, weighs less than 300 grams (about half a pound) and is equipped with a central fuselage, two flexible wings, and a steerable tail. The body contains a battery and a waterproof electric motor that drives a crankshaft, which pumps the wings up and down at preset frequencies. The wings are made of thin membranes that are coated with hydrophobic nanoparticles to help wick away water. And the tail is motorized, enabling it to change its angle to help the robot fly up or dive down.

In experiments carried out in a water tank and at Lake Geneva, a team led by Raphael Zufferey, an assistant professor of mechanical engineering at MIT, identified combinations of wing size, flapping frequency, and tail angle that enable the robot to smoothly transition from swimming to flying. 

The best results came with medium-size wings that were flexible enough to minimize flapping amplitude in water and also firm enough to keep the robot aloft in the air. The speeds and flapping frequencies were similar to those used by actual birds, and a pitch of 70 degrees—a relatively steep angle—allowed the robot to make the leap from water to air. Interestingly, although many diving birds paddle their feet to help them take off from the water’s surface, the team found that the bot didn’t need feet at all.

The engineers’ results could help pave the way for a new class of drones and vehicles that could fly to and sample from aquatic regions too dangerous for traditional vessels to access.

“Our dream vision is for oceanographers, marine biologists, and members of coastal communities to launch this robot from a boat, or from shore, and it would fly close to the area of interest, such as an iceberg or a port facility, or over a pod of whales,” says Zufferey. “It would dive into the water to take a measurement or collect a sample, and fly back to deliver the data at a fraction of the cost of traditional methods. Then it could go back out to dive for more.” 

The researchers are now trying to design wings that can turn as well as flap. They will also test the robot’s performance under turbulent conditions, such as swimming in choppy waters and flying through wind. Then they hope to deploy the vehicle to help answer questions in ocean science.

“One of the major challenges in ocean science is collecting data both frequently and across many locations, which is something this robot could do in the future,” Zufferey says. “You could send this out not just every week, but every hour. It could fly out at high speeds, dive in, fly back, deliver its data, and go back out, multiple times.” 

When Tristan Brown, an associate professor of history at MIT, first examined a Chinese tea chest label displayed at Old South Meeting House, he had no reason to doubt its story. Descendants of the Boston blacksmith Thomas Wells had donated the label in 1987, saying it had been recovered after colonial protesters threw tea into Boston Harbor in 1773. 

But after a year of research, Brown reached a different conclusion: The label was made nearly a century later. The decisive clue came when he read the Chinese text in Cantonese rather than Mandarin, as previous scholars had done. He found that the characters had been used phonetically, in slightly variant forms across contemporary sources, to represent the name of Smith, Archer & Co., a US firm that acquired Asian tea for shipment to American markets during the 1860s and 1870s.

COURTESY OF MIT GLOBAL HUMANITIES

Working with the Wells family, he traced the label to a relative who traveled from Michigan to California during the Gold Rush era before returning and operating a business known as the California Tea Store. Brown argues that claims for its revolutionary pedigree probably developed later, amid the centennial commemorations of the 1870s.

The discovery does not make the label historically insignificant, he says. Instead, what began as an inquiry into a supposed artifact of the Boston Tea Party became a study of how ordinary objects acquire historical authority, and how historical memory itself is made.

“History is never finished,” he says. “Even objects that have sat in museums for decades can reveal entirely new stories when we ask new questions.” 

The average American throws out around 81 pounds of clothing each year, and there are few options for recycling it. MIT engineers hope to cut down on that textile waste with a new type of yarn. 

The thermoplastic yarn mimics the properties of conventional elastic yarns, which typically combine spandex with polyester or nylon. Those fibers would have to be separated for recycling—a process that isn’t practical. But the MIT team found a way to create a similarly stretchy yarn from two variations of polyethylene, a material commonly used in milk jugs and grocery bags. Because they come from the same chemical family, the yarn can be melted as is. Svetlana Boriskina, who led the work as a research scientist in the Department of Mechanical Engineering, says a garment made from this material could then be spun into new yarn for a next generation of clothing. Even after 10 cycles of melting and respinning, the yarn stays as strong and flexible as conventional thread. 

“Now we have something that can be knitted and woven,” Boriskina says. “That is the next stage.” Someday, the researchers hope, a polyethylene garment could be dropped in a collection bin and sent to a recycling facility, promoting a more sustainable, circular textile economy. 

A high-fat, low-carbohydrate diet can help some people lose weight, and some research has shown that it may protect against colon cancer. But a new study suggests that such a ketogenic diet may also increase the risk of cancer in the small intestine.

This type of diet forces the body to burn fatty acids instead of carbohydrates for fuel, producing by-products called ketone bodies. One of these, BHB, was thought to be responsible for the protective effect observed against colon cancer.

Omer Yilmaz, director of the MIT Stem Cell Initiative, worked with colleagues including MIT postdocs Jessica Shay and Fangtao Chi to investigate whether the effects were similar in the small intestine. But instead, they found that mice on a ketogenic diet were more likely to develop tumors in that part of the gastrointestinal system than those on a control diet were. 

Additional studies revealed that this tumor growth was driven by the way intestinal cells burn dietary fat for energy—a metabolic pathway called fatty acid oxidation. This pathway activates proteins that signal stem cells to multiply more rapidly. 

“Having more stem cells means that when you injure the small intestine, it can repair itself better, but the downside is that having more active stem cells can lead to tumor formation,” Yilmaz says.

Though the researchers confirmed that a ketogenic diet suppressed the development of colon tumors, their findings suggest that ketone bodies are not involved. “These molecules are essentially metabolic bystanders,” Yilmaz says.

One implication is that commercial ketone supplements probably do little to either help or harm people who take them. But the deeper issue is “why the same diet has opposite consequences in two adjacent parts of the gut,” Chi says. “That is what we are working to understand next.”

Whatever they discover, as Yilmaz says, “the message here is that we need to be very careful in generalizing the effects that these diets can have.” 

Strokes leave 5 million people with long-term impairments each year, and a growing shortage of physical therapists makes it hard for them to get the care they need. A new approach tries to solve that problem by combining artificial intelligence and human therapy. 

Johannes Lachner, a former MIT postdoc who is now an assistant professor at Purdue University, and Noah Geiger, a former visiting student at MIT, developed a robotic system that uses generative AI and real-time force feedback to learn from real therapists. Drawing on what it’s learned, it gives patients just the right amount of assistance during physical rehabilitation exercises like reaching, lifting their arms, and performing tasks of daily living.

The goal is “not to replace therapists, but to extend their reach,” Lachner says. 

“Initial robotic experiments have already demonstrated the feasibility of this approach,” he reports. “The next phase of the project aims to develop therapist-specific models and evaluate them in a long-term clinical study with the same patients who previously received manual therapy.” Beyond that, he envisions possible applications in contact-rich industrial settings or collaborative workspaces.