How E-Reader Tech Mimics Octopuses
A sample of squid skin shows its colors. Some of the latest color e-reader technology in development works much like squid, octopus and cuttlefish skin, a new study has found.
CREDIT: From "Insane in the Chromatophores" by Backyard Brains Video Lab on YouTube
In the future, e-reader owners may open up their devices to see full-color pages, rendered using the same methods octopuses use to show and hide colors. Some of the latest color e-reader technology in labs today mimics octopuses, cuttlefish and squid, according to a new study.
For instance, the world's physically lightest and best-quality color e-reader display, which is under development at HP, uses the same techniques that octopuses do when camouflaging themselves or showing off during mating displays. Like the displays on black-and-white E Ink readers available today, the new display isn't backlit and it uses much less energy than backlit tablet or smartphone screens. The quality of color it produces is on par with print newspaper.
"We found it to be interesting that the most powerful approach for generating color in nature and in man, in terms of these devices, was the same," said Jason Heikenfeld, an engineer who directs the Novel Devices Laboratory at the University of Cincinnati and who led the new research. He worked with engineers and biologists from the U.S. Air Force, U.S. Army and the Marine Biological Laboratory in Woods Hole, Mass., to collect examples of squidlike e-readers. [E-reader vs Octopus Tech Battle!! (Infographic)]
E-readers and octopuses have to solve the same physics problem when they produce color, Heikenfeld told TechNewsDaily. Both have to produce color without producing light, unlike glowing LCD screens or fireflies.
Yet e-reader researchers haven't purposefully looked to octopuses for inspiration. The HP display's cuttlefishlike qualities were a coincidence. Heikenfeld himself has invented color e-paper technology that he only later realized mimicked squid, he said.
He hopes that by carefully examining cephalopods, a color-changing class of animals that include octopuses and their relatives, researchers will think of even better color e-reader displays that are flexible or are able to change textures.
Octopus pigment sacs for e-readers
Showing and hiding colors like octopus skin does is one of the most advanced cephalopodlike technologies in e-readers. Cephalopods have tiny sacs of pigment in their skin, called chromatophores. If they want to show certain colors, they flex the muscles attached to the right chromatophores.
"They just basically stretch this sac out," Heikenfeld said. "Then you can see more colors as a result. And then we they let go and relax, this little sac of pigment goes back to a spherical shape, which is not visible."
Color e-paper, including that of the tech company HP, works in the same way, Heikenfeld and his colleagues found. Instead of using muscles to control the sacs of color, however, e-paper uses electric fields. A voltage applied to the pigment molecules makes them clump together and hide in tiny pits in the e-reader display, where they're not visible. Take away the voltage, and the molecules spread out, creating color that people are able to see at the surface of the display.
"You might not use the same materials and chemistry, but the approach is the same," Heikenfeld said.
Other e-paper tech in development has taken inspiration from another structure in cephalopod skin, iridophores. Photonic crystal ink is made of a rigid, transparent material whose special structure reflects light, producing brilliant colors. Iridophores have similar structures, allowing them to produce colors for cephalopods.
Both iridophores and photonic crystal ink are able to alter the spacing of their reflective structures to switch between colors. Both are even able to reflect wavelengths people can't see, such as ultraviolet light or infrared waves. That may not be too useful for e-readers, but cephalopods sometimes use UV and infrared markings to signal to one another.
More to learn
In many ways, technology has already outstripped octopuses at displaying colors, Heikenfeld and his colleagues found. E-paper in development shows better color quality than cephalopod skin. E-paper is also able to change colors more quickly than these sea creatures because the electronics that e-paper uses to control its colors are more precise than muscles.
Yet there's still a lot to learn from cephalopods, Heikenfeld said. "Some of these marine creatures can crinkle their skin to recreate the texture of coral on demand," he said. What if TV or smartphone displays could do the same? That could make for especially realistic-looking images, or provide a textured surface for people to type on — all while displaying color, like octopuses do.
While several labs are working on flexible screens, none are able to show color, Heikenfeld added. "So the biological systems are ahead there, as well," he said. "It'd be great if you could roll up an iPad and stuff it in your pocket."
Heikenfeld and his colleagues published their study of octopuslike e-paper yesterday (Sept. 25) in the U.K.-based Journal of the Royal Society Interface.