Qualcomm challenges LCDs through new e-reader

Qualcomm challenges LCDs through new e-reader

  10:00:00 PM    Science Lover

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A new electronic display is poised to challenge power-hungry LCDs after U.S. mobile chip maker Qualcomm Inc. teamed up with a South Korean bookseller to introduce a new e-reader.

The "Kyobo eReader"

A new electronic display is poised to challenge power-hungry LCDs after US mobile chip maker Qualcomm Inc. teamed up with a South Korean bookseller to introduce a new e-reader. The "Kyobo eReader" was unveiled this week in Seoul and will reach South Korean consumers as early as December 1, Kyobo Book Centre officials said Thursday. The e-reader features Qualcomm's 1.0 GHz "Snapdragon" processor, a custom Kyobo application based on Android and a 5.7 inch "XGA" mirasol display.

The mirasol display uses ambient light instead of its own in much the same way that a peacock's plumage gets its scintillating hues. Qualcomm's mirasols have already been used in a few Chinese and South Korean phones, and in an MP3 player on the US market. The display contains tiny mirrors that consume power only when they're moving, easing battery drain. Mirasol displays also quickly change from one image to the next and show video.

The global market for e-readers is dominated by bright LCDs and grayscale "e-ink" screens. LCDs consume relatively more battery power while e-ink screens are slow to refresh. The introduction of the e-reader jointly developed by Qualcomm and Kyobo signals increasing competition in the global market for tablets.

US online retailer Amazon.com Inc. and bookseller Barnes & Noble Inc. have recently released tablets of their own, Kindle Fire and Nook Tablet, and are challenging Apple's iPad in pricing.



Qualcomm CEO Paul Jacobs noted South Koreans' near-100 percent literacy rate and digital reading skills during a launching ceremony in Seoul on Tuesday, according to the San Diego-based company. Fifteen-year-old South Koreans scored highest in their ability to absorb information from digital devices, according to a 2009 study by the Organization for Economic Cooperation and Development. Over 80 percent of households in South Korea have broadband Internet access. The e-reader featuring the mirasol display will be priced at 349,000 won, or $302, said Seoul-based Kyobo, South Korea's largest bookseller.

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Researchers create rollerball-pen ink to draw circuits

Researchers create rollerball-pen ink to draw circuits

  9:30:00 PM    Science Lover

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Two professors from the University of Illinois; one specializing in materials science, the other in electrical engineering, have combined their talents to take the idea of printing circuits onto non-standard materials one step further by developing a conductive ink that can be used in a traditional rollerball ink pen to draw circuits by hand onto paper and other porous materials. In their paper published in Advanced Materials, team leads Jennifer Lewis, Jennifer Bernhard and colleagues describe how they were able to make a type of ink from silver nanoparticles that would remain a liquid while in the pen, but would dry like regular ink once applied. The pen could was then used to draw a functioning LCD display and an antenna.

To make the ink, the team produced silver nanoparticles by reducing a silver nitrate solution along with an acid to prevent the particles from growing too large. Afterwards the acid was removed and the viscosity of the ink modified using hydroxyethyl cellulose to get just the right consistency. The result is a sort of liquid metal that dries on contact and which can be used to conduct electricity, hence its ability to be used in the creation of a circuit.

University of Illinois engineers developed a pen with
conductive silver ink that can write electric circuits and
interconnects directly on paper and other surfaces.
Credit: Bok Yeop Ahn

Up till now, most research on printing circuits onto non-standard materials, such as paper, have been done using inkjet printers or even airbrushes. This new approach would allow circuits to be drawn quicker and much cheaper, or even on-the-fly, as no other hardware is needed. Such a low cost device might create a market for throwaway circuits or even super cheap batteries. Paper was used in the study because it is considered to be the most suitable non-standard material for printing circuits due to its wide availability, low cost, ability to be bent and shaped, and the fact that it is biodegradable.



Lewis noted that the paper used in study was folded after testing to see how the circuit would hold up, and discovered it took folding several thousand times before the ink pathways were broken. She also noted that other materials besides paper could be used, such as wood or ceramics.

This is a flexible array of LEDs mounted on paper.
Hand-drawn silver ink lines form the interconnects
between the LEDs. Credit: Bok Yeop Ahn

The team next plans to look into other types of materials that might be used to make conductive ink for their pen, hoping to open up the door to all kinds of inks that can be used for a wide variety of purposes.

More information: Pen-on-Paper Flexible Electronics, Advanced Materials, Article first published online: 20 JUN 2011. DOI:10.1002/adma.201101328

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LCD Projector Used to Control Brain and Muscles of Tiny Organisms Such as Worms

LCD Projector Used to Control Brain and Muscles of Tiny Organisms Such as Worms

  10:22:00 AM    Science Lover

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Researchers are using inexpensive components from ordinary liquid crystal display (LCD) projectors to control the brain and muscles of tiny organisms, including freely moving worms. Red, green and blue lights from a projector activate light-sensitive microbial proteins that are genetically engineered into the worms, allowing the researchers to switch neurons on and off like light bulbs and turn muscles on and off like engines.

Hang Lu, an associate professor in the School of Chemical 
& Biomolecular Engineering at Georgia Tech, and her 
graduate students Jeffrey Stirman (left) and Matthew Crane 
are using inexpensive LCD projectors to control the brain 
and muscles of tiny organisms, including freely moving 
worms. (Credit: Georgia Tech/Gary Meek)

Use of the LCD technology to control small animals advances the field of optogenetics -- a mix of optical and genetic techniques that has given researchers unparalleled control over brain circuits in laboratory animals. Until now, the technique could be used only with larger animals by placement of an optical fiber into an animal's brain, or required illumination of an animal's entire body.

A paper published Jan. 9 in the advance online edition of the journal Nature Methods describes how the inexpensive illumination technology allows researchers to stimulate and silence specific neurons and muscles of freely moving worms, while precisely controlling the location, duration, frequency and intensity of the light.

"This illumination instrument significantly enhances our ability to control, alter, observe and investigate how neurons, muscles and circuits ultimately produce behavior in animals," said Hang Lu, an associate professor in the School of Chemical & Biomolecular Engineering at the Georgia Institute of Technology.

Lu and graduate students Jeffrey Stirman and Matthew Crane developed the tool with support from the National Institutes of Health and the Alfred P. Sloan Foundation.

The illumination system includes a modified off-the-shelf LCD projector, which is used to cast a multi-color pattern of light onto an animal. The independent red, green and blue channels allow researchers to activate excitable cells sensitive to specific colors, while simultaneously silencing others.

"Because the central component of the illumination system is a commercially available projector, the system's cost and complexity are dramatically reduced, which we hope will enable wider adoption of this tool by the research community," explained Lu.

By connecting the illumination system to a microscope and combining it with video tracking, the researchers are able to track and record the behavior of freely moving animals, while maintaining the lighting in the intended anatomical position. When the animal moves, changes to the light's location, intensity and color can be updated in less than 40 milliseconds.

Once Lu and her team built the prototype system, they used it to explore the "touch" circuit of the worm Caenorhabditis elegans by exciting and inhibiting its mechano-sensory and locomotion neurons. Alexander Gottschalk, a professor in the Johann Wolfgang Goethe-University Frankfurt Institute of Biochemistry in Frankfurt, Germany, and his team provided the light-sensitive optogenetic reagents for the Georgia Tech experiments.

For their first experiment, the researchers illuminated the head of a worm at regular intervals while the animal moved forward. This produced a coiling effect in the head and caused the worm to crawl in a triangular pattern. In another experiment, the team scanned light along the bodies of worms from head to tail, which resulted in backward movement when neurons near the head were stimulated and forward movement when neurons near the tail were stimulated.

Additional experiments showed that the intensity of the light affected a worm's behavior and that several optogenetic reagents excited at different wavelengths could be combined in one experiment to understand circuit functions. The researchers were able to examine a large number of animals under a variety of conditions, demonstrating that the technique's results were both robust and repeatable.

"This instrument allowed us to control defined events in defined locations at defined times in an intact biological system, allowing us to dissect animal functional circuits with greater precision and nuance," added Lu.

While these proof-of-concept studies investigated the response of C. elegans to mechanical stimulation, the illumination system can also be used to evaluate responses to chemical, thermal and visual stimuli. Researchers can also use it to study a variety of neurons and muscles in other small animals, such as the zebrafish and fruit fly larvae.

"Experiments with this illumination system yield quantitative behavior data that cannot be obtained by manual touch assays, laser cell ablation, or genetic manipulation of neurotransmitters," said Lu.

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Energy Harvesting: Nanogenerators Grow Strong Enough to Power Small Conventional Electronic Devices

Energy Harvesting: Nanogenerators Grow Strong Enough to Power Small Conventional Electronic Devices

  10:22:00 AM    Science Lover

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Blinking numbers on a liquid-crystal display (LCD) often indicate that a device's clock needs resetting. But in the laboratory of Zhong Lin Wang at Georgia Tech, the blinking number on a small LCD signals the success of a five-year effort to power conventional electronic devices with nanoscale generators that harvest mechanical energy from the environment using an array of tiny nanowires.

In a new technique for producing nanogenerators,
researchers transfer vertically-aligned nanowires to a 
flexible substrate. (Credit: Courtesy of Zhong Lin Wang)

In this case, the mechanical energy comes from compressing a nanogenerator between two fingers, but it could also come from a heartbeat, the pounding of a hiker's shoe on a trail, the rustling of a shirt, or the vibration of a heavy machine. While these nanogenerators will never produce large amounts of electricity for conventional purposes, they could be used to power nanoscale and microscale devices -- and even to recharge pacemakers or iPods.

Wang's nanogenerators rely on the piezoelectric effect seen in crystalline materials such as zinc oxide, in which an electric charge potential is created when structures made from the material are flexed or compressed. By capturing and combining the charges from millions of these nanoscale zinc oxide wires, Wang and his research team can produce as much as three volts -- and up to 300 nanoamps.

"By simplifying our design, making it more robust and integrating the contributions from many more nanowires, we have successfully boosted the output of our nanogenerator enough to drive devices such as commercial liquid-crystal displays, light-emitting diodes and laser diodes," said Wang, a Regents' professor in Georgia Tech's School of Materials Science and Engineering. "If we can sustain this rate of improvement, we will reach some true applications in healthcare devices, personal electronics, or environmental monitoring."

Recent improvements in the nanogenerators, including a simpler fabrication technique, were reported online last week in the journal Nano Letters. Earlier papers in the same journal and in Nature Communications reported other advances for the work, which has been supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. Department of Energy, the U.S. Air Force, and the National Science Foundation.

"We are interested in very small devices that can be used in applications such as health care, environmental monitoring and personal electronics," said Wang. "How to power these devices is a critical issue."

The earliest zinc oxide nanogenerators used arrays of nanowires grown on a rigid substrate and topped with a metal electrode. Later versions embedded both ends of the nanowires in polymer and produced power by simple flexing. Regardless of the configuration, the devices required careful growth of the nanowire arrays and painstaking assembly.

In the latest paper, Wang and his group members Youfan Hu, Yan Zhang, Chen Xu, Guang Zhu and Zetang Li reported on much simpler fabrication techniques. First, they grew arrays of a new type of nanowire that has a conical shape. These wires were cut from their growth substrate and placed into an alcohol solution.

The solution containing the nanowires was then dripped onto a thin metal electrode and a sheet of flexible polymer film. After the alcohol was allowed to dry, another layer was created. Multiple nanowire/polymer layers were built up into a kind of composite, using a process that Wang believes could be scaled up to industrial production.

When flexed, these nanowire sandwiches -- which are about two centimeters by 1.5 centimeters -- generated enough power to drive a commercial display borrowed from a pocket calculator.

Wang says the nanogenerators are now close to producing enough current for a self-powered system that might monitor the environment for a toxic gas, for instance, then broadcast a warning. The system would include capacitors able to store up the small charges until enough power was available to send out a burst of data.

While even the current nanogenerator output remains below the level required for such devices as iPods or cardiac pacemakers, Wang believes those levels will be reached within three to five years. The current nanogenerator, he notes, is nearly 100 times more powerful than what his group had developed just a year ago.

Writing in a separate paper published in October in the journal Nature Communications, group members Sheng Xu, Benjamin J. Hansen and Wang reported on a new technique for fabricating piezoelectric nanowires from lead zirconate titanate -- also known as PZT. The material is already used industrially, but is difficult to grow because it requires temperatures of 650 degrees Celsius.

In the paper, Wang's team reported the first chemical epitaxial growth of vertically-aligned single-crystal nanowire arrays of PZT on a variety of conductive and non-conductive substrates. They used a process known as hydrothermal decomposition, which took place at just 230 degrees Celsius.

With a rectifying circuit to convert alternating current to direct current, the researchers used the PZT nanogenerators to power a commercial laser diode, demonstrating an alternative materials system for Wang's nanogenerator family. "This allows us the flexibility of choosing the best material and process for the given need, although the performance of PZT is not as good as zinc oxide for power generation," he explained.

And in another paper published in Nano Letters, Wang and group members Guang Zhu, Rusen Yang and Sihong Wang reported on yet another advance boosting nanogenerator output. Their approach, called "scalable sweeping printing," includes a two-step process of (1) transferring vertically-aligned zinc oxide nanowires to a polymer receiving substrate to form horizontal arrays and (2) applying parallel strip electrodes to connect all of the nanowires together.

Using a single layer of this structure, the researchers produced an open-circuit voltage of 2.03 volts and a peak output power density of approximately 11 milliwatts per cubic centimeter.

"From when we got started in 2005 until today, we have dramatically improved the output of our nanogenerators," Wang noted. "We are within the range of what's needed. If we can drive these small components, I believe we will be able to power small systems in the near future. In the next five years, I hope to see this move into application."

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Tiny Logo Demonstrates Advanced Display Technology Using Nano-Thin Metal Sheets

Tiny Logo Demonstrates Advanced Display Technology Using Nano-Thin Metal Sheets

  5:22:00 PM    Science Lover

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In a step toward more efficient, smaller and higher-definition display screens, a University of Michigan professor has developed a new type of color filter made of nano-thin sheets of metal with precisely spaced gratings.

An optical microscopy image of a 12-by-9-micron U-M logo 
produced with this new color filter process. (Credit: Jay Guo)

The gratings, sliced into metal-dielectric-metal stacks, act as resonators. They trap and transmit light of a particular color, or wavelength, said Jay Guo, an associate professor in the Department of Electrical Engineering and Computer Science. A dielectric is a material that does not conduct electricity.

"Simply by changing the space between the slits, we can generate different colors," Guo said. "Through nanostructuring, we can render white light any color."

A paper on the research is published Aug. 24 in Nature Communications.

His team used this technique to make what they believes is the smallest color U-M logo. At about 12-by-9 microns, it's about 1/6 the width of a human hair.

Conventional LCDs, or liquid crystal displays, are inefficient and manufacturing-intensive to produce. Only about 5 percent of their back-light travels through them and reaches our eyes, Guo said. They contain two layers of polarizers, a color filter sheet, and two layers of electrode-laced glass in addition to the liquid crystal layer. Chemical colorants for red, green and blue pixel components must be patterned in different regions on the screen in separate steps.

Guo's color filter acts as a polarizer simultaneously, eliminating the need for additional polarizer layers. In Guo's displays, reflected light could be recycled to save much of the light that would otherwise be wasted.

Because these new displays contain fewer layers, they would be simpler to manufacture, Guo said. The new color filters contain just three layers: two metal sheets sandwiching a dielectric. Red, green and blue pixel components could be made in one step by cutting arrays of slits in the stack. This structure is also more robust and can endure higher- powered light.

Red light emanates from slits set around 360 nanometers apart; green from those about 270 nanometers apart and blue from those approximately 225 nanometers apart. The differently spaced gratings essentially catch different wavelengths of light and resonantly transmit through the stacks.

"Amazingly, we found that even a few slits can already produce well-defined color, which shows its potential for extremely high-resolution display and spectral imaging," Guo said.

The pixels in Guo's displays are about an order of magnitude smaller than those on a typical computer screen. They're about eight times smaller than the pixels on the iPhone 4, which are about 78 microns. He envisions that this pixel size could make this technology useful in projection displays, as well as wearable, bendable or extremely compact displays.

The paper is called "Plasmonic nano-resonators for high resolution color filtering and spectral imaging."

Guo is also an associate professor in the Department of Macromolecular Science and Engineering. This research is supported in part by the Air Force Office of Scientific Research and the Defense Advanced Research Projects Agency. The university is pursuing patent protection for the intellectual property and is seeking commercialization partners to help bring the technology to market.

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