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In Living Color

By on February 27th, 2013

Emily Dickinson wrote that “hope is the thing with feathers,” while Woody Allen added, “The thing with feathers has turned out to be my nephew. I must take him to a specialist in Zurich.” Now, however, the thing with feathers is the inspiration for a new imaging technology. Namely, the peacock.

Biomimicry or biomimetics is a term used to refer to man-made products, processes, systems, or technologies that have been inspired by something nature has already come up with. Birds, of course, have inspired the idea of human flight. Velcro was famously invented after Swiss engineer Georges de Mestral examined burrs that had become stuck on his clothing. And there is a type of tape called Gecko Tape that adheres to surfaces by means of tiny nanoscale hairs—much like those found on the feet of geckos.

Along those same lines, the peacock—known for its elaborate plumage—is helping inspire a new kind of imaging technology that doesn’t require chemicals or even power. As LiveScience explains, the showy, iridescent tail feathers of the peacock “contain nanometer-scale protein structures that break up incoming light waves, recombine, and reflect them as rich, vibrant colors.” (By the way, the phrase “male peacock” is redundant; collectively, males and females of the species are called peafowl, and the female is a peahen. Offspring? Peachicks.) And as the peacock—only the male has the garish plumage—struts around as part of a courtship display, different colors are reflected at different angles, creating a shimmering, iridescent effect.

Now, researchers at the University of Michigan are developing a technology that uses this same basic process to create what could be a future generation of smartphone or tablet display. Instead of feathers, though:

Guo’s team uses metals, which interact with light in more complicated ways. They create metal structures with nanoscale grooves that produce iridescent colors, but also trap the light so that viewers can see the intended colors from all angles.

The trick, Guo said, was to get light to enter grooves much smaller than the wavelengths of light. By etching the grooves a certain length it will absorb that color. By doing this, the researchers were also able to beat something called the diffraction limit, in which they can create picture elements, or pixels, smaller than half the wavelength of the light, to generate detailed color.

They etched nanoscale grooves on a piece of glass with the same technology used to etch computer chips. Each groove was made just the right size to absorb a certain color, and then the coated the glass with silver. When they shined light on the glass, the grooves created the color image. To demonstrate the process, the researchers reproduced an image of the Olympic rings, with resolution so good, each full color ring was about 20 microns across, smaller than half the width of a human hair.

The process is still in its infancy, and at present only works for static images. It is touted as “green” in that it does not use chemicals or even power to produce an image. However, whilst the display itself would require no chemicals, presumably the etching process would. Any kind of practical commercialization is along way off, if it ever is destined for such, but it’s an interesting idea.