Color-shifting cuttlefish inspire TV screens

By Eric Bland

updated 1:13 p.m. ET May 12, 2009

Cuttlefish are masters of disguise, able to change their skin color in less than a second to hide from predators or draw in prey for the kill. Now, scientists from MIT and elsewhere are developing cuttlefish-inspired electronic ink and screens that use less than one-hundredth the power of traditional television screens.

"Cuttlefish change their color by secreting different chemicals to change the spacing between membranes," said Edwin Thomas, a professor at MIT who recently co-authored a paper describing his team's new screen in the journal Advanced Materials.

"We have created an artificial electrical system to control the spacing between layers," he said, thereby changing the colors on the screen.

The current screen prototype is several square inches across but only one micron thick. Crammed into that narrow space are 20 to 30 layers of alternating "dirt cheap polystyrene that doesn't do anything," said Thomas, and "responsive" poly-2 vinyl.

At rest, with no electrical charge, the screen is clear. As the voltage increases, the poly-2 vinyl expands, becoming thicker and thicker while reflecting ever longer wavelengths of light, starting with blue and finishing with red at 10 volts.

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The screen can also reflect non-visible wavelengths of light, such as infrared and ultraviolet, depending on the voltage applied. It can produce images using only a few volts because it doesn't create light, it only reflects it. In a dark room with no light, the screen would remain dark.

The screen is so easy to assemble, said Thomas, that he that is working with a Boston area science teacher to produce a version cheap enough, safe enough and simple enough for middle and high school students to build in chemistry class.

MIT isn't the only institution working on reflective screens. Microsoft, Sun Chemical Corp., the University of Cincinnati and Cornell University all have active reflective screen research units, all for a variety of different purposes. Electronic ink applications, pressure sensors and advertising billboards are only a few of the potential applications.

"The tunability of these systems is fantastic," said Stephen Foulger, a professor at Clemson University also working on reflective screens. "There is a huge span of colors and applications."

Though the screens are cheap to make, they have some drawbacks, said Foulger. Most reflective screens have a limited viewing angle; if you aren't directly in front of the screen it can be hard to see the image. Since the screens reflect light instead of creating light, they can only be used in a lit area.

"Sometimes this is a problem, sometimes its not," said Foulger. "But this is a nice system that has a huge span of colors, and that can often trump problems like viewing angle."

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