David Kirkpatrick

August 11, 2010

Improving displays

And display improvements are increasingly important given the rapid evolution in types of consumer electronics — e-readers, smartphones, more complex touch screens, tablet/pad computers, et.al. — and the different types of high-performance displays needed to maximize these technologies.

The release:

Better displays ahead

IMAGE: This is a prototype of the vertical stack multi-color electrowetting display device is shown in the photograph. Arrays of ~1,000-2,000 pixels were constructed with pixel sizes of 200 × 600…

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This release is also available in Chinese.College Park, MD (August 10, 2010) — Sleek design and ease of use are just two of the main reasons consumers are increasingly attracted to tablets and e-readers. And these devices are only going to get better — display technology improvements are on the way.

Several e-reader products on the market today use electrophoretic displays, in which each pixel consists of microscopic capsules that contain black and white particles moving in opposite directions under the influence of an electric field. A serious drawback to this technology is that the screen image is closer to black-on-gray than black-on-white. Also, the slow switching speed (~1 second) due to the limited velocity of the particles prevents integration of other highly desirable features such as touch commands, animation, and video.

Researchers at the University of Cincinnati Nanoelectronics Laboratory are actively pursuing an alternative approach for low-power displays. Their assessment of the future of display technologies appears in the American Institute of Physics’ Applied Physics Letters.

“Our approach is based on the concept of vertically stacking electrowetting devices,” explains professor Andrew J. Steckl, director of the NanoLab at UC’s Department of Electrical and Computer Engineering. “The electric field controls the ‘wetting’ properties on a fluoropolymer surface, which results in rapid manipulation of liquid on a micrometer scale. Electrowetting displays can operate in both reflective and transmissive modes, broadening their range of display applications. And now, improvements of the hydrophobic insulator material and the working liquids enable EW operation at fairly low driving voltages (~15V).”

Steckl and Dr. Han You, a research associate in the NanoLab, have demonstrated that the vertical stack electrowetting structure can produce multi-color e-paper devices, with the potential for higher resolution than the conventional side-by-side pixel approach. Furthermore, their device has switching speeds that enable video content displays.

What does all of this mean for the consumer? Essentially, tablets and e-readers are about to become capable of even more and look even better doing it. Compared to other technologies, electrowetting reflective display screens boast many advantages. The electrowetting displays are very thin, have a switching speed capable of video display, a wide viewing angle and, just as important, Steckl says, they aren’t power hogs.


The article, “Three-Color Electrowetting Display Device for Electronic Paper” by Han You and Andrew J. Steckl will appear in the journal Applied Physics Lettershttp://apl.aip.org/applab/v97/i2/p023514_s1

Image Caption: A prototype of the vertical stack multi-color electrowetting display device is shown in the photograph. Arrays of ~1,000-2,000 pixels were constructed with pixel sizes of 200 × 600 and 300 × 900 µm.


Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). See: http://apl.aip.org/


The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world’s largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

June 15, 2010

Organic nanoelectronics

As the title of this release puts it, “one step closer.”

The release:

Organic nanoelectronics a step closer

Researchers use metal crystal to organize organic materials, overcoming key stumbling block

This release is avaiable in French.

IMAGE: This image shows the polymers that were created at a resolution of 5 nanometers (the average strand of human hair is 80,000 nanometers wide).

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Although they could revolutionize a wide range of high-tech products such as computer displays or solar cells, organic materials do not have the same ordered chemical composition as inorganic materials, preventing scientists from using them to their full potential. But an international team of researchers led by McGill’s Dr. Dmitrii Perepichka and the Institut national de la recherche scientifique’s Dr. Federico Rosei have published research that shows how to solve this decades-old conundrum. The team has effectively discovered a way to order the molecules in the PEDOT, the single most industrially important conducting polymer.

Although Dr. Perepichka is quick to point out that the research is not directly applicable to products currently in the market, he gives the example of a possible use for the findings in computer chips. “It’s a well known principle that the number of transistors in a computer chip doubles every two years,” he said, “but we are now reaching the physical limit. By using molecular materials instead of silicon semiconductor, we could one day build transistors that are ten times smaller than what currently exists.” The chips would in fact be only one molecule thick.

The technique sounds deceptively simple. The team used an inorganic material – a crystal of copper – as a template. When molecules are dropped onto the crystal, the crystal provokes a chemical reaction and creates a conducting polymer. By using a scanning probe microscope that enabled them to see surfaces with atomic resolution, the researchers discovered that the polymers had imitated the order of the crystal surface. The team is currently only able to produce the reaction in one dimension, i.e. to make a string or line of molecules. The next step will be to add a second dimension in order to make continuous sheets (“organic graphite”) or electronic circuits.


Perepichka is affiliated with McGill University’s department of chemistry and Rosei is affiliated with Institut national de la recherche scientifique – Énergie Matériaux Télécommunications Center, a member of the Université du Québec network. Their research was published online by theProceedings of the National Academy of Sciences and was funded by the Natural Sciences and Engineering Research Council of Canada, the Air Force Office of Scientific Research and Asian Office of Aerospace Research and Development of the USA, the Petroleum Research Fund of the American Chemical Society, the Fonds québécois de recherche sur la nature et les technologies, and the Ministère du Développement économique, de l’Innovation et de l’Exportation of Quebec.