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Everybody's a winner
Automatic window-shading invention tops a strong field of entries in materials competition.

David L. Chandler, MIT News Office
October 7, 2011

Two students who invented a window that can automatically deploy a set of internal blinds to prevent a room from overheating on hot summer days won the $10,000 first prize in this year’s Making And Designing Materials Engineering Competition (MADMEC), which took place Thursday evening.

The window, called iReflect, developed by graduate students Elizabeth Rapoport and Ahmed Al-Obeidi of the Department of Materials Science and Engineering (DMSE), has strips of infrared-blocking film in the space between its two panes. When warmed by sunlight, the strips unfurl to block some of the incoming light — especially the infrared light responsible for most heating — while still allowing occupants to see out. 

The principle is simple, and similar to the bimetallic strips used in typical thermostats: Two materials with different thermal characteristics (the rate at which they expand when heated) are bonded together. When the temperature changes, one material expands more than the other, causing the bonded strips to curl or uncurl.

“In winter, we wanted to allow the sun to shine through,” Rapoport explains, “and in summer, to block it” — or at least enough of it to prevent too much heating of the air inside. The system is completely passive: “It goes in and out of the way without anyone doing anything,” she says.

The idea still needs some further work to make it practical, Rapoport says, but “we think we’re pretty close.” The polymer materials they used for their prototype are “somewhat dark,” she concedes. In further research, she says, she and Al-Obeidi might try perforating the film to produce a mesh, allowing more light to pass through.

The annual competition, now in its fifth year, is run by DMSE, and is sponsored by the companies Saint Gobain, BP and Dow Chemical. The contest’s theme is “materials solutions for alternative energy.”

iReflect was not the only window-blocking technology in the contest. Another of the five teams, called D-Light, produced a window that combines a photochromic material (similar to glasses that turn dark in sunlight) with a system for generating electricity through thin photovoltaic cells at the window’s edges. The window “combines passive shading with a layer that extracts energy,” explains team member Geraldine Paulus, a graduate student in chemical engineering. D-Light won second place, with a prize of $6,000.

Two teams shared the third-place prize of $4,000. One, called Voltaphon, designed a system to generate electricity from sound waves by creating resonant cavities that amplify certain frequencies of sound. The sound waves then vibrate piezoelectric material that produces electricity from the vibration; the idea is to produce systems that could automatically power lights, or data transmission, from ambient noise. The other third-prize winner, called Phasewear, designed a system to make clothing that automatically changes its thickness and insulation as the temperature varies; the system uses the same kind of bilayer polymers as those used by iReflect to block incoming light.

Although the contest was supposed to have just three prizes, the judges this year were so impressed with the overall quality of all the entries that they decided to add an additional prize of $1,000, which was awarded to a team called GigaNanoHydro Power, which designed a system for harvesting electricity from falling water.

“I think this was definitely the strongest field of entries in the five years” of MADMEC, says Michael Tarkanian, a technical instructor in DMSE who has been one of the judges each year. “All five were well done, well thought out, well designed and well executed,” he says, “which made the judging difficult.”

Although the entries are designed from scratch for the competition, some teams have gone on to start companies to commercialize their inventions. The most successful of these has been Levant Power, which placed third in the first MADMEC, in 2007. The company, which has designed shock absorbers that improve vehicle handling while generating electricity to improve overall efficiency, is opening a new 15,000-square-foot headquarters in Woburn, Mass., later this month, and has performed successful tests with the U.S. military and with New York City transit buses.


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