By collecting the suns energy during the day,these lightweight fabrics provide bright white light at night.Their inventors have named the fabricsPortable (轻便的)Lights.Portable Lights have the potential to transform the lives of people without electricity around the world,says project leader Sheila Kennedy.
Our invention,Kennedy says,came from seeing how we could transform technology we saw every day in the United States and move it into new markets for people who didnt have a lot of money.
At the core of Portable Light technology are devices called high-brightness light-emitting diodes (高亮度发光二极管),or HB LEDs. These tiny lights appear in digital clocks,televisions,and streetlights.
LEDs are completely different from the light bulbs (灯泡).Most of those glass bulbs belong to a type called incandescent lights (白炽灯).Inside,electricity heats a metal coil (线圈)to about 2,200 degrees Celsius.At that temperature,bulbs give off light we can see.
Ninety percent of energy produced by incandescent lights,however,is heat-and invisible. With all that wasted energy,bulbs bum out quickly.They are also easily broken.
LEDs,on the other hand,are like tiny pieces of rock made up of molecules (分子)that are arranged in a crystal structure.When an electric current passes through an LED,the crystal structure produces light.Unlike incandescent bulbs,they can produce light of various colors.Within an LED,the type of molecules and their particular arrangement determines what color is produced.
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