Changing Color With Smart Windows

Nanoparticle based windows could switch colors on demand.

Nanoparticle-based windows could switch colors on demand: One day, you might not need special bulbs to give your room's lighting a different hue -- you'd just tell the windows themselves to change. Rice University researchers have discovered that you can change the colors transmitted through glass by sending a voltage through pairs of gold and silver nanoparticles, which you frequently find in stained glass windows. Jolt a window one way and you'd get a bright red; reverse the voltage and you'd get blue. All you're really doing is forming or removing chemical bridges between the particles.

The technology is still far from production, so don't expect to renovate your home just yet. However, you only need tiny amounts of the precious metals to achieve dramatic effects. As such, you might well find yourself upgrading to color shifting smart windows around the whole home, not just in one or two prime locations.

Medieval artisans unwittingly used nanotechnology when they mixed gold chloride into molten glass to create richly hued stained glass windows. Soon we could have full-color displays or stained-glass windows that change color at the flick of an electrical switch, thanks to the same kinds of light-scattering nanoparticles.

We’re one step closer to such wondrous things with a new method for connecting metal nanoparticles via teensy “drawbridges” of thin layers of silver, developed by researchers at Rice University. This lets them link pairs of nanoparticles that scatter different colors of light together to form simple color displays. The scientists described their work in a new paper in Science Advances.

Nanoparticles are special because they straddle the boundary between the macroscopic and quantum realms, where classical physics and quantum mechanics hold sway, respectively. It’s their size that matters: a nanometer is equivalent to one 25-millionth of an inch, and nanoparticles range in size from a few nanometers to several hundred nanometers. That gives them unusual properties not found in the same elements at the macro scale.

This includes optical properties, notably how metal nanoparticles in particular scatter light. Scientists have analyzed medieval stained glass windows, and found gold and silver nanoparticles are the key to the deep reds and yellows found therein.

The gold nanoparticles absorb blue and yellow light; red light, with its longer wavelength, reflects off them and passes through the glass. Something similar happens with silver nanoparticles; only bright yellow light scatters off and passes through the glass. Make gold spheres a bit larger, and you can get green or orange. Make the silver nanoparticles smaller, and you get blue.

They have interesting chemically reactive properties, too. In 2008, for instance, scientists at Queensland University of Technology found that some stained glass windows actually helped purify the air when the sun shone through them. The secret ingredient was gold nanoparticles. Sunlight activated the nanoparticles so they could destroy volatile organic chemicals (VOCs) — the source of that new car smell, for instance, but toxic if inhaled in larger quantities.

The properties of medieval stained glass are so unique, Welsh scientists recently used their own versions of the material to build a special 3D panoramic camera for the European Space Agency’s 2019 Mars rover mission. In that case, the useful property was the way the glass resists fading — even after hundreds of years of exposure to the sun’s UV radiation. By blocking UV radiation, the nanoparticles in the stained glass chips will capture the true colors of the red planet.

Soon We Could Have Displays and Windows That Change Color with the Flick of a Switch. But it’s proven challenging to induce metal nano particles to switch colors, a critical ability if you want to build a color display with them. Past work has managed some slight shifts in hue by linking nanoparticles with nanowire bridges. The Rice scientists improved on those techniques to make the color shifts stronger via a kind of chemical bridge.

First, the Rice team fixed pairs of gold nanoparticles to a glass surface coated with conductive indium tin oxide, or ITO (it’s in your smartphone screen, for instance). They used the ITO to coat the surface of the gold particles with a silver electroplate. Then they immersed them in saltwater electrolyte with a silver electrode to form a circuit. Zap the nanoparticles with a negative voltage, and a conductive silver “drawbridge” forms. Reverse the voltage, and the bridge withdraws.

“The great thing about these chemical bridges is that we can create and eliminate them simply by applying or reversing a voltage,” group leader Christy Landes said in a press release. “This is the first method yet demonstrated to produce dramatic, reversible color changes for devices built from light-activated nano particles.”

Ching Ching For Window Washer Xiong Of ChongQing

Xiong, a migrant worker, lost 6,000 yuan when cleaning glasses of a high building in Fuzhou of Fujian province. She put all the 6.000 in a money bag, tied to her waist, but the bag loosened and the money fell from the 8th floor. Xiong just got back 300 yuan and all the other 5,700 were picked by passers-by on the street. After Xiong's story hit the internet and reported by media, she has received a total of 15,000 yuan in donations.

Migrant worker loses 6,000 yuan, receives 15,000 more in donations from strangers: A migrant worker who lost 6,000 yuan while cleaning the window glass of a high building in Fuzhou, Fujian Province has received around 15,000 yuan in donations after her story hit the internet and was reported by the media. The 40-year-old woman, surnamed named Xiong, put 6,000 yuan in a bag and tied it to her waist as she was hoisted up to clean the high-rise building's windows. The bag loosened and the money fell from the 8th floor, scattering all over the streets. As to expect when it's literally raining money, most of the cash was scooped up by passersby, and Xiong was only able to recover 300 yuan. Xiong, whose story circulated the web, was brought to tears by the generosity of those who pitched in.

Window washer’s savings more than doubled by returned money, donations: Money that fluttered to the ground from a bag that a window washer dropped while working on a high rise — the savings of a migrant couple for their son’s tuition — was not only returned to her but more than doubled by donations from generous citizens after her plight was reported. The migrant woman, surnamed Xiong, kept 6,000 yuan (US$982) in notes in a small cloth bag with her. While she was working on Wednesday, the hand-made purse slipped and the notes fell to the ground from the 8th floor.

Xiong, 44, a native of Chongqing in southwest China, works in Fuzhou in east China’s Fujian Province with her husband. She planned to pay for her son’s tuition with the money that the couple earned this year, so she carried it with her for safekeeping. Xiong had recovered only 300 yuan by Wednesday night, while the rest of the notes were picked up by passers-by, state television broadcaster CCTV reported. By yesterday, however, after the television report, Xiong had received a total of more than 15,000 yuan, including money returned by some of the passers-by and donations.

Wind takes RMB6,000 from Fuzhou woman; goodwill returns 15,000: Xiong Faming was at a loss when the wind snatched away most of the 6,000 yuan (US$990) in her unzipped waist bag and scattered it out from the 8th floor of a building. Rushing down from the ledge where she had been cleaning glass, she only recovered 300 yuan (US$49) after a futile search. Fortunately, the residents of Fuzhou, hearing of her plight, have done something extraordinary, reports the Chongqing Morning Post.

Xiong and her husband, both from Chongqing, had scraped together 6,000 yuan after a year of work. Xiong is hired for cleaning jobs and her husband takes what he can find, mostly manual labor. On a good month, he can make around 3,000 and 4,000 yuan (US$400-$600). Some months he makes nothing. They had planned to take the money back to Chongqing for the Chinese New Year holiday, which begins in late January. Xiong had the money stored in the bag she fastens to her waist when cleaning windows in the city, a bag that had opened and emptied unbeknown to her. By the time she looked back, it had already disappeared. All she could do was cry.

They routinely send back 1,500 yuan (US$250) a month back to their hometown in Chongqing, where they have a daughter in high school and a son in primary school. For them, the lost money is a fortune. Miraculously, Xiong "doesn't hate at all the people who picked up the lost money." She said, "I can only blame myself." Xiong reported the incident to the Fuzhou police department, and police called on local residents via the city newspaper to to return the money they picked up to her. They left Xiong's bank account number. That same day, Xiong's account received more than 7,000 yuan (US$1,150) in donations. The company which had hired Xiong for cleaning the glass sent her 6,000 yuan (US$990) and wished her well. "Enough, enough, thank you so much," Xiong said. "I'll remember everyone who has helped me."

Luck? That's not luck, - this is Luck..

Cleaners working on an aircraft in eastern India have found 24 gold bars worth more than £890,000 hidden in a toilet compartment - the latest in a series of smuggling attempts uncovered at the country's airports. The cleaners had boarded the Jet Airways plane at Kolkata (formerly Calcutta) airport after it had travelled from the eastern city of Patna. It had earlier been flying on international routes that included the Middle East.

Gold bars worth $1.1m found in plane toilet in India: A stash of 24 gold bars worth more than $1.1m has been discovered in the toilet compartment of a commercial plane in eastern India. Cleaners found the haul in two bags on board a Jet Airways flight at Kolkata airport, officials said. India is one of the world's main gold consumers and imports are seen as a major contributor to the country's account deficit. It recently raised duty on imports of gold jewellery to 15% from 10%. It was the third increase this year as the government attempts to curb demand for the precious metal, which many Indians traditionally hoard in the belief it will bring financial security.

The plane on which the 1kg (2.2lb) gold bars were found on Tuesday had reportedly come from Bangkok, local media reported, before making stops in India. "The cleaning staff of the airport were going though their routine duties and found two bags in the toilets of the plane," airport director BP Mishra told AFP news agency. He was quoted as saying that no arrest had been made in connection with the find, though OneIndia News said a suspect was being questioned. The gold has been valued at between 70m and 90m rupees (up to $1.4m or £890,000).