Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Next-gen e-readers: Improved 'peacock' technology could lock in color for high-res displays

Iridescence, or sheen that shifts color depending on your viewing angle, is pretty in peacock feathers. But it's been a nuisance for engineers trying to mimic the birds' unique color mechanism to make high-resolution, reflective, color display screens.

Now, researchers at the University of Michigan have found a way to lock in so-called structural color, which is made with texture rather than chemicals. A paper on the work is published online in the current edition of the Nature journal Scientific Reports.

In a peacock's mother-of-pearl tail, precisely arranged hairline grooves reflect light of certain wavelengths. That's why the resulting colors appear different depending on the movement of the animal or the observer. Imitating this system—minus the rainbow effect—has been a leading approach to developing next-generation reflective displays.

The new U-M research could lead to advanced color e-books and electronic paper, as well as other color reflective screens that don't need their own light to be readable. Reflective displays consume much less power than their backlit cousins in laptops, tablet computers, smartphones and TVs. The technology could also enable leaps in data storage and cryptography. Documents could be marked invisibly to prevent counterfeiting.

Led by Jay Guo, professor of electrical engineering and computer science, the researchers harnessed the ability of light to funnel into nanoscale metallic grooves and get trapped inside. With this approach, they found the reflected hues stay true regardless of the viewer's angle.

"That's the magic part of the work," Guo said. "Light is funneled into the nanocavity, whose width is much, much smaller than the wavelength of the light. And that's how we can achieve color with resolution beyond the diffraction limit. Also counterintuitive is that longer wavelength light gets trapped in narrower grooves."

The diffraction limit was long thought to be the smallest point you could focus a beam of light to. Others have broken the limit as well, but the U-M team did so with a simpler technique that also produces stable and relatively easy-to-make color, Guo said.

"Each individual groove—much smaller than the light wavelength—is sufficient to do this function. In a sense, only the green light can fit into the nanogroove of a certain size," Guo said.

The U-M team determined what size slit would catch what color light. Within the framework of the print industry standard cyan, magenta and yellow color model, the team found that at groove depths of 170 nanometers and spacing of 180 nanometers, a slit 40 nanometers wide can trap red light and reflect a cyan color. A slit 60 nanometers wide can trap green and make magenta. And one 90 nanometers wide traps blue and produces yellow. The visible spectrum spans from about 400 nanometers for violet to 700 nanometers for red.

"With this reflective color, you could view the display in sunlight. It's very similar to color print," Guo said.

To make color on white paper, (which is also a reflective surface), printers arrange pixels of cyan, magenta and yellow in such a way that they appear to our eyes as the colors of the spectrum. A display that utilized Guo's approach would work in a similar way.

To demonstrate their device, the researchers etched nanoscale grooves in a plate of glass with the technique commonly used to make integrated circuits, or computer chips. Then they coated the grooved glass plate with a thin layer of silver. When light—which is a combination of electric and magnetic field components—hits the grooved surface, its electric component creates what's called a polarization charge at the metal slit surface, boosting the local electric field near the slit. That electric field pulls a particular wavelength of light in.

Right now, the new device can make static pictures, and the researchers hope to develop a moving picture version in the near future.

The research is funded by the Air Force Office of Scientific Research and the National Science Foundation. The paper is titled "Angle-Insensitive Structural Colours based on Metallic Nanocavities and Coloured Pixels beyond the Diffraction Limit."

Jay Guo:

Nicole Casal Moore | EurekAlert!
Further information:

More articles from Power and Electrical Engineering:

nachricht Discovery about new battery overturns decades of false assumptions
07.10.2015 | Oregon State University

nachricht New polymer creates safer fuels
02.10.2015 | California Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Reliable in-line inspections of high-strength automotive body parts within seconds

Nondestructive material testing (NDT) is a fast and effective way to analyze the quality of a product during the manufacturing process. Because defective materials can lead to malfunctioning finished products, NDT is an essential quality assurance measure, especially in the manufacture of safety-critical components such as automotive B-pillars. NDT examines the quality without damaging the component or modifying the surface of the material. At this year's Blechexpo trade fair in Stuttgart, Fraunhofer IZFP will have an exhibit that demonstrates the nondestructive testing of high-strength automotive body parts using 3MA. The measurement results are available in a matter of seconds.

To minimize vehicle weight and fuel consumption while providing the highest level of crash safety, automotive bodies are reinforced with elements made from...

Im Focus: Kick-off for a new era of precision astronomy

The MICADO camera, a first light instrument for the European Extremely Large Telescope (E-ELT), has entered a new phase in the project: by agreeing to a Memorandum of Understanding, the partners in Germany, France, the Netherlands, Austria, and Italy, have all confirmed their participation. Following this milestone, the project's transition into its preliminary design phase was approved at a kick-off meeting held in Vienna. Two weeks earlier, on September 18, the consortium and the European Southern Observatory (ESO), which is building the telescope, have signed the corresponding collaboration agreement.

As the first dedicated camera for the E-ELT, MICADO will equip the giant telescope with a capability for diffraction-limited imaging at near-infrared...

Im Focus: Locusts at the wheel: University of Graz investigates collision detector inspired by insect eyes

Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.

Inspired by insects

Im Focus: Physicists shrink particle accelerator

Prototype demonstrates feasibility of building terahertz accelerators

An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...

Im Focus: Simple detection of magnetic skyrmions

New physical effect: researchers discover a change of electrical resistance in magnetic whirls

At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At...

All Focus news of the innovation-report >>>



Event News

EHFG 2015: Securing healthcare and sustainably strengthening healthcare systems

01.10.2015 | Event News

Conference in Brussels: Tracking and Tracing the Smallest Marine Life Forms

30.09.2015 | Event News

World Alzheimer`s Day – Professor Willnow: Clearer Insights into the Development of the Disease

17.09.2015 | Event News

Latest News

Using optical fiber to generate a two-micron laser

09.10.2015 | Process Engineering

Sea turtles face plastic pollution peril

09.10.2015 | Ecology, The Environment and Conservation

Antioxidants cause malignant melanoma to metastasize faster

09.10.2015 | Health and Medicine

More VideoLinks >>>