Researchers at the University of Illinois at Chicago (UIC) and Korea University have developed an ultra-thin, transparent and conductive film that is bendable and stretchable, offering a potential new way to develop roll-up touchscreen displays, wearable electronics, flexible solar cells and electronic skin.
Bendable Nanomaterial Could Usher in New Types of Wearable
23 November 2016
The film is made up of fused silver nanowires produced by spraying the nanowire particles through a tiny jet nozzle at supersonic speed. What results is a film with nearly the same electrical conductivity of a silver plat and the transparency of glass.
The long, thin nanowires measure about 20 microns long (about the width of a human hair), but the diameter is a thousand times smaller. The transparent flexible film can be bent repeatedly and stretched to seven times its original length and still work, researchers say.
How They Did It
By suspending the nanowire particles in water, researchers were able to propel them by air through a de Laval nozzle, a millimeters-small tube that has the same geometry as a jet engine. The liquid must be atomized so it evaporates in flight.
When the nanowires strike the surface, they are applied at supersonic speed and fuse together as the kinetic energy is transferred to heat. Researchers discovered that 400 meters per second was the ideal speed. If the energy is too high, it cuts the wires; if it is too low, there is not enough heat to fuse the wires.
“It should be easier and cheaper to fabricate, as it's a one-step versus a two-step process,” says Alexander Yarin, UIC Distinguished Professor of Mechanical Engineering. “You can do it roll-to-roll on an industrial line, continuously.”
The UIC researchers earlier this year fabricated a transparent conducting film by electroplating a mate of tangled nanofiber with copper. In comparison, this silver nanowire offers better scalability and production rate.
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