Content By David L. Chandler

David L. Chandler’s picture

By: David L. Chandler

As a cucumber plant grows, it sprouts tightly coiled tendrils that seek out supports to pull the plant upward. This ensures the plant receives as much sunlight exposure as possible. Now, researchers at MIT have found a way to imitate this coiling-and-pulling mechanism to produce contracting fibers that could be used as artificial muscles for robots, prosthetic limbs, or other mechanical and biomedical applications.

Although many different approaches have been used for creating artificial muscles, including hydraulic systems, servo motors, shape-memory metals, and polymers that respond to stimuli, they all have limitations, including high weight or slow response times. The new fiber-based system, by contrast, is extremely lightweight and can respond very quickly, the researchers say. The findings have been reported in the journal Science.

The new fibers were developed by MIT postdoc Mehmet Kanik and MIT graduate student Sirma Örgüç, working with professors Polina Anikeeva, Yoel Fink, Anantha Chandrakasan, C. Cem Taşan, and five others. The group used a fiber-drawing technique to combine two dissimilar polymers into a single strand of fiber.

David L. Chandler’s picture

By: David L. Chandler

A team of engineers has built and tested a radically new kind of airplane wing, assembled from hundreds of tiny identical pieces. The wing can change shape to control the plane’s flight, and could provide a significant boost in aircraft production, flight, and maintenance efficiency, the researchers say.

The new approach to wing construction could afford greater flexibility in the design and manufacturing of future aircraft. The new wing design was tested in a NASA wind tunnel and is described today in a paper in the journal Smart Materials and Structures, co-authored by research engineer Nicholas Cramer at NASA Ames in California; MIT alumnus Kenneth Cheung, now at NASA Ames; Benjamin Jenett, a graduate student in MIT’s Center for Bits and Atoms; and eight others.

Instead of requiring separate movable surfaces such as ailerons to control the roll and pitch of the plane, as conventional wings do, the new assembly system makes it possible to deform the whole wing, or parts of it, by incorporating a mix of stiff and flexible components in its structure. The tiny subassemblies, which are bolted together to form an open, lightweight lattice framework, are then covered with a thin layer of similar polymer material as the framework.

David L. Chandler’s picture

By: David L. Chandler

Applying just a bit of strain to a piece of semiconductor or other crystalline material can deform the orderly arrangement of atoms in its structure enough to cause dramatic changes in its properties, such as the way it conducts electricity, transmits light, or conducts heat.

Now, a team of researchers at MIT and in Russia and Singapore have found ways to use artificial intelligence to help predict and control these changes, potentially opening up new avenues of research on advanced materials for future high-tech devices.

The findings appear this month in the Proceedings of the National Academy of Sciences, in a paper authored by Ju Li, MIT professor of nuclear science and engineering and of materials science and engineering; MIT Principal Research Scientist Ming Dao, and MIT graduate student Zhe Shi, with Evgeni Tsymbalov and Alexander Shapeev at the Skolkovo Institute of Science and Technology in Russia; and Subra Suresh, the Vannevar Bush Professor Emeritus and former dean of engineering at MIT and current president of Nanyang Technological University in Singapore.

David L. Chandler’s picture

By: David L. Chandler

Photo: Greg Hren/RLE

Researchers at MIT have succeeded in making a fine thread that functions as a diode, a device at the heart of modern electronics. This feat—made possible by a new approach to a type of fiber manufacturing known as fiber drawing—could open up possibilities for fabricating a wide variety of electronic and photonic devices within composite fibers, using a variety of materials.

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By: David L. Chandler

It seems like a no-brainer: Remanufacturing products rather than making new ones from scratch—widely done with everything from retread tires to refilled inkjet cartridges to remanufactured engines—should save a lot of energy, right?

Not so fast, says a new study by researchers at the Massachusetts Institute of Technology (MIT).

In some cases, the conventional wisdom is indeed correct. But out of 25 case studies on products in eight categories done by a team led by MIT professor of mechanical engineering Timothy Gutowski, there were just as many cases where remanufacturing actually cost more energy as cases where it saved energy. And for the majority of the items, the savings were negligible, or the energy balance was too close to call.

Why are the new results so different from what might have been assumed? The MIT team looked at the total energy used over the lifetime of a product—a life-cycle analysis—rather than just the energy used in the manufacturing process itself. In virtually all cases, it costs less money and less energy to make a product from the recycled “core”—the reusable part of the product—than to start from scratch.

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By: David L. Chandler

In a finding that has met with surprise and some controversy in the scientific community, researchers at the Massachusetts Institute of Technology (MIT) and elsewhere have discovered a basic property that governs the way water and many other liquids behave as their temperature changes.

Liquids have long been known to exhibit a rapid change in properties near a point called the “glass transition temperature,” where the viscosity of the liquid—its “thickness,” or resistance to flow—becomes very large. But MIT professor Sow-Hsin Chen and his co-researchers have found a different transition point at a temperature about 20 to 30 percent higher, which they call the “dynamic crossover temperature.” This temperature may be at least as important as the glass transition temperature, and the viscosity at the dynamic crossover temperature seems to have a universal value for a large class of liquids (known as glass-forming liquids) that includes such familiar substances as water, ammonia, and benzene.

David L. Chandler’s picture

By: David L. Chandler

You can check a person’s vital signs—pulse, respiration, and blood pressure—manually or by attaching sensors to the body. But a student in the Harvard-Massachusetts Institute of Technology (MIT) Health and Sciences Technology program is working on a system that could measure these health indicators just by putting a person in front of a low-cost camera such as a laptop computer’s built-in webcam.

So far, graduate student Ming-Zher Poh has demonstrated that the system can indeed extract accurate pulse measurements from ordinary low-resolution webcam imagery. Now he’s working on extending the capabilities so it can measure respiration and blood-oxygen levels. He hopes eventually to be able to monitor blood pressure as well. Initial results of his work, carried out with the help of media lab student Daniel McDuff and professor of media arts and sciences Rosalind Picard, were published in the Optics Express journal in May 2010.