Nanotube ink: Desktop printing of carbon nanotube patterns

Using an off-the-shelf inkjet printer, a team of scientists has developed a simple technique for printing patterns of carbon nanotubes on paper and plastic surfaces. The method, which is described in the August 2006 issue of the journal Small, could lead to a new process for manufacturing a wide range of nanotube-based devices, from flexible electronics and conducting fabrics to sensors for detecting chemical agents.
Carbon nanotubes have enticed researchers since their discovery in 1991, offering an impressive combination of high strength, low weight, and excellent conductivity. But most current techniques to make nanotube-based devices require complex and expensive equipment. "Our results suggest new alternatives for fabricating nanotube patterns by simply printing the dissolved particles on paper or plastic surfaces," said Robert Vajtai, a researcher with the Rensselaer Nanotechnology Center at Rensselaer Polytechnic Institute and corresponding author of the paper.
Vajtai and his colleagues at Rensselaer - along with a group of researchers led by Krisztián Kordás and Géza Tóth at the University of Oulu in Finland - have developed an approach that uses a commercial inkjet printer to deposit nanotubes onto various surfaces. They simply fill a conventional ink cartridge with a solution of carbon nanotubes dissolved in water, and then the printer produces a pattern just as if it was printing with normal ink. Because nanotubes are good conductors, the resulting images also are able to conduct electricity.
"Printed carbon nanotube structures could be useful in many ways," Vajtai said. "Some potential applications based on their electrical conductivity include flexible electronics for displays, antennas, and batteries that can be integrated into paper or cloth." Printing electronics on cloth could allow people to actually "wear" the battery for their laptop computer or the entire electronic system for their cell phone, according to Vajtai.
The technique could be used to print optical tags on money and other paper items that need to be tracked, and it could even lead to an electronic newspaper where the text can be switched without changing the paper, he said. The researchers printed different samples, some of which show sensitivity to the vapors of several chemicals, which also could make them useful as gas sensors.
The approach is simple, versatile, and inexpensive, which makes it superior to other methods for producing conductive surfaces, according to Vajtai. "A great advantage of our process is that the printed patterns do not require curing, which is known to be a limiting factor for conventional conductive ink applications," he said. "And since our ink is a simple water-based dispersion of nanotubes, it is environmentally friendly and easy to handle and store."
Because the process uses off-the-shelf printers, cartridges, and paper or plastic surfaces, the only real expense is the cost of the nanotubes. For this experiment, the researchers made their own multi-walled carbon nanotubes, which were then chemically modified to allow them to dissolve in water. But similar nanotubes can be purchased for as little as a tenth of the price of the more expensive single-walled variety of carbon nanotubes, Vajtai said. And the cost of nanotubes should continue to drop as commercial demand for higher volumes grows.
The researchers plan to continue optimizing the process to improve the quality of the nanotube ink and the conductivity of the printed images. At present, the paper or plastic must be run through the printer multiple times to get an electrically conductive pattern, with the conductivity increasing after each repetition. They also hope to experiment with different chemical modifications to produce a diversity of ink "colors," each producing surface patterns with different properties, Vajtai said.
Contact: Jason Gorss
gorssj@rpi.edu
518-276-6098
Rensselaer Polytechnic Institute

Polymers show promise for lab-on-a-chip technology

Researchers are touting the use of liquid crystalline polymers (LCP) as a viable tool for use in devices such as the sought-after lab-on-a-chip technology.
University of Alberta researchers, collaborating with colleagues at the Eindhoven University of Technology and Phillips Research Laboratories in the Netherlands, have shown that LCP, when formed into a thin film on a glass backing, can be fabricated and patterned on a microscale. The research was published recently in the Journal of Material Chemistry.
"Based on our research of liquid crystalline polymers, we anticipate the emergence of exciting new techniques in microfabrication that can be used to cheaply and efficiently pattern response materials," said Anastasia Elias, a PhD student in Dr. Michael Brett's group in the U of A Department of Electrical and Computer Engineering and the first author of the paper.
LCPs are often described as "artificial muscles" that can convert thermal, chemical and electromagnetic stimuli into mechanical energy, Elias said. LCPs are polymers made from liquid crystalline molecules, which are well-known for their use in display applications, such as laptop computer screens, where they are used for their unique optical properties.
Elias and her colleagues conducted a number of preliminary LCP experiments on a microscale in order to better understand and describe the material's mechanical properties. They believe the material holds promise as a microscale building block. It's now up to other engineers and scientist to take this knowledge and create useful microscale devices.
The most commonly cited goal among micro- and nanoscale researchers is to create a lab-on-a-chip – a tiny system that could be used, for example, to analyze blood samples and biopsies much faster, cheaper and more comprehensively than current methods.
In the past, most microscale research and development funds have targeted silicon, the fundamental material in the semiconductor industry. But LCPs are less brittle and more pliable than silicon, Elias said, adding that LCP devices could be tailored to respond to specific external stimuli, such as temperature changes and UV radiation exposure, which could makes them easier to activate than silicon. And, perhaps most importantly of all, LCPs are less expensive than silicon and potentially easier to process, Elias said.
"Ultimately, we believe liquid crystalline polymers will be fully integrated in microelectromechanical systems, such as the emerging lab-on-a-chip applications," she said.
Contact: Ryan Smith
ryan.smith@ualberta.ca
780-492-0436
University of Alberta

Why some men go bald prematurely ?

Could super furry animals provide clues for baldness?
Scientists looking at mice may have discovered why certain people are hairier than others in what could provide clues as to the reason .
The University of Manchester team has laid bare the molecular processes that determine which embryonic skin cells will form into hair follicles and determine the body's hair pattern.
The findings will be of interest to scientists looking at male-pattern baldness but have more direct implications for people who suffer from ectodermal dysplasia - a range of conditions where skin cells fail to develop into other tissue, including hair follicles.
"During human development, skin cells have the ability to turn into other types of cells to form hair follicles, sweat glands, teeth and nails," said Dr Denis Headon, who led the research. "Which cells are transformed into hair follicles is determined by three proteins that are produced by our genes.
"Our research has identified how one of these proteins working outside of the cell interacts at a molecular level to determine an individual's hair pattern as the embryonic skin spatially organises itself."
The team found that cells given the genetic command to become hair follicles will send out signals to neighbouring cells to prevent them from doing likewise, so producing a specific hair pattern.
They also demonstrated that by hyperactivating the 'hair protein' in embryonic mice, young with considerably more fur than normal were produced.
"We were able to change the number of hair follicles in the embryonic mice while they were developing in the womb," said Dr Headon, who is based in the University's Faculty of Life Sciences.
"The findings could have implications for sufferers of ectodermal dysplasia that are missing this particular protein and who are unable to develop hair follicles during embryonic development.
"The research - while not directly linked to male-pattern baldness - should be of interest to pharmaceutical companies working in this field as understanding the molecular processes at work during follicle development could provide clues as to why follicles shrink and hair growth diminishes in certain men as they get older."
Contact: Aeron Haworth
aeron.haworth@manchester.ac.uk
44-077-178-81563
University of Manchester

Snapfish by HP Boosts Online Photo Sharing and Services

PALO ALTO, Calif.
Snapfish by HP today announced several new online photo services and products that enable its members – which now number more than 30 million – to share and create digital stories in new ways.
Highlighting the new services are Snapfish Group Rooms, which offer groups of users – for example, extended families, youth organizations or little league parents – a way to upload, store and share photos in a communal environment that is safe and secure.
With Group Rooms, members upload their individual photos into a common area, where they can collaborate on photo projects such as photo books, calendars or cards; share albums with family and friends outside the group; and automatically receive updates when room content has been added or changed.
Members also can customize their rooms with design themes, descriptions and personalized URLs (for example, smithreunion.snapfish.com). In addition, unlike with most competitive offerings, an unlimited number of rooms can be created at Snapfish for free.
“The Snapfish website consistently delivers a recipe of personalization, controlled community and value people are looking for,” said Ben Nelson, general manager, Snapfish by HP. “These latest features help users creatively organize and share their stories with family and friends, while complementing our basic value proposition, including high-quality prints for just 12 cents each – almost 40 percent lower than major competitors – plus free online sharing and storage.”
Snapfish also has greatly expanded options for many of its popular photo products:
Personalization options for photo calendars, including the ability to add important dates such as birthdays and anniversaries. Each addition can be made unique with custom text, borders and even photos for individual dates. Additionally, Snapfish is now offering new backgrounds, themes and caption options.
Sixty-eight new holiday greeting card designs for holiday celebrations, including Christmas, Hanukkah, Kwanzaa and New Year’s templates.
Greater selection of Snapfish’s award-winning MemoryBooks, which allow consumers to tell their stories in fresh and creative ways. In addition to the current hardbound, coffee table-quality MemoryBook, starting in mid-September Snapfish will offer softbound, “On-the-Go” MemoryBooks with 10 cover choices starting at $12.99 for the first 20 pages, and 3 x 4-inch PocketBooks, which easily fit in a purse or pocket and are sold in sets of three for $14.99.
Also available in mid-September, expanded features across the entire line of MemoryBooks, including five new background styles with exclusive designs, borders and text-only templates; the ability to preview in a full-screen viewing environment; and the ability to share online versions of MemoryBooks with family and friends.
Snapfish also has updated its site with new organizational features. Enhancements include:
A new sub-navigation system on the left side of the photo viewing experience, allowing users to access their Snapfish albums with fewer keystrokes;
Chronological, alphabetical and “by friend” organization options for easier categorization;
A “favorites” album, which can be customized with a user’s favorite photos and videos; and
A preview pop-up feature, which allows users to quickly preview the content of albums without actually opening the album, helping members save time.
About HP
HP is a technology solutions provider to consumers, businesses and institutions globally. The company’s offerings span IT infrastructure, global services, business and home computing, and imaging and printing. For the four fiscal quarters ended July 31, 2006, HP revenue totaled $90.0 billion. More information about HP (NYSE, Nasdaq: HPQ) is available at http://www.hp.com.
This news release contains forward-looking statements that involve risks, uncertainties and assumptions. If such risks or uncertainties materialize or such assumptions prove incorrect, the results of HP and its consolidated subsidiaries could differ materially from those expressed or implied by such forward-looking statements and assumptions. All statements other than statements of historical fact are statements that could be deemed forward-looking statements, including but not limited to statements of the plans, strategies and objectives of management for future operations; any statements concerning expected development, performance or market share relating to products and services; anticipated operational and financial results; any statements of expectation or belief; and any statements of assumptions underlying any of the foregoing. Risks, uncertainties and assumptions include the achievement of expected results and other risks that are described from time to time in HP’s Securities and Exchange Commission reports, including but not limited to the risks described in HP’s Quarterly Report on Form 10-Q for the fiscal quarter ended April 30, 2006, and other reports filed after HP’s Annual Report on Form 10-K for the fiscal year ended Oct. 31, 2005. HP assumes no obligation and does not intend to update these forward-looking statements.
© 2006 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.

MIT proton treatment could replace x-ray use in radiation therapy

Scientists at MIT, collaborating with an industrial team, are creating a proton-shooting system that could revolutionize radiation therapy for cancer. The goal is to get the system installed at major hospitals to supplement, or even replace, the conventional radiation therapy now based on x-rays.
The fundamental idea is to harness the cell-killing power of protons -- the naked nuclei of hydrogen atoms -- to knock off cancer cells before the cells kill the patient. Worldwide, the use of radiation treatment now depends mostly on beams of x-rays, which do kill cancer cells but can also harm many normal cells that are in the way.
What the researchers envision -- and what they're now creating -- is a room-size atomic accelerator costing far less than the existing proton-beam accelerators that shoot subatomic particles into tumors, while minimizing damage to surrounding normal tissues. They expect to have their first hospital system up and running in late 2007.
Physicist Timothy Antaya, a technical supervisor in MIT's Plasma Science and Fusion Center, was deeply involved in developing the new system and is now working to make it a reality. He argues it "could change the primary method of radiation treatment" as the new machines are put in place.
The beauty of protons is that they are quite energetic, but their energy can be controlled so they do less collateral damage to normal tissues, compared to powerful x-ray beams. Protons enter the body through skin and tissue, hit the tumor and stop there, minimizing other damage.
Protons are far more massive than the photons in x-rays, and the x-rays tend to pass directly through tissues and can harm living cells along the entire path. The side effects often include skin burns and other forms of tissue damage.
The new machines, in fact, should allow radiation specialists to deposit a far bigger dose of killing power inside the tumor, but spare more of the surrounding normal tissues. This is expected to increase tumor control rates while minimizing side effects.
Because of their high energy and controllability, protons have been used as anti-cancer bullets in the past, with promising results. But medical centers can't easily come up with the $100 million or more needed to build a proton machine dedicated to this medical use. That's because protons are produced inside the huge, expensive atomic accelerators that are usually employed at major atomic research centers, including national laboratories.
Now, Antaya and his colleagues at MIT and at Still River Systems Inc. think they can provide the new machine for far less money, have it occupy just one moderate-size hospital treatment room, and achieve better results than x-ray therapy. MIT is licensing the technology to Still River Systems.
Industry is already showing acute interest in the new technology because more than half of all cancer patients are now treated with radiation, meaning there are two million radiation patients worldwide. That offers a huge market for an effective new radiation system, and the directors of major cancer research and treatment centers are already enthusiastic, Antaya said.
Antaya recalled that the initial push to build a new proton-making system came from a radiation physicist, Kenneth Gall, at the University of Texas at Dallas Medical Center. "He had a good idea for a single-room proton treatment facility, but hadn't found anyone who thought it was possible to build," Antaya said. Gall is now at Still River Systems as a co-founder.
In his own research experience, Antaya had worked with new types of cyclotrons -- they were called "atom smashers" years ago -- using new "superconducting" coils to generate the necessary magnetic fields. As a result, he could see a "nexus between all the required technologies and how we could pick a reasonable set of properties, with a good chance of being successful," he said.
Building it is quite a challenge, however. "This is an accelerator that's going to be in the room with the patient, so it's quite a difficult design exercise" just in terms of safety issues, Antaya said. But he and his colleagues are betting it will work as expected.
The magnet work of the Technology and Engineering Division of the Plasma Science and Fusion Center, led by senior research engineer Joseph Minervini, is key to the new system. That work has been funded by the U.S. Department of Energy Office of Fusion Energy Science.

'Nanocantilevers' yield surprises critical for designing new detectors

This rendition depicts an array of tiny, diving-boardlike devices called nanocantilevers. The devices are coated with antibodies to capture viruses, which are represented as red spheres.
WEST LAFAYETTE, Ind. - Researchers at Purdue University have made a discovery about the behavior of tiny structures called nanocantilevers that could be crucial in designing a new class of ultra-small sensors for detecting viruses, bacteria and other pathogens.
The nanocantilevers, which resemble tiny diving boards made of silicon, could be used in future detectors because they vibrate at different frequencies when contaminants stick to them, revealing the presence of dangerous substances. Because of the nanocantilever's minute size, it is more sensitive than larger devices, promising the development of advanced sensors that detect minute quantities of a contaminant to provide an early warning that a dangerous pathogen is present.
The researchers were surprised to learn that the cantilevers, coated with antibodies to detect certain viruses, attract different densities - or quantity of antibodies per area - depending on the size of the cantilever. The devices are immersed into a liquid containing the antibodies to allow the proteins to stick to the cantilever surface.
"But instead of simply attracting more antibodies because they are longer, the longer cantilevers also contained a greater density of antibodies, which was very unexpected," said Rashid Bashir, a researcher at the Birck Nanotechnology Center and a professor of electrical and computer engineering and biomedical engineering at Purdue University. The research also shows that the density is greater toward the free end of the cantilevers.
The engineers found that the cantilevers vibrate faster after the antibody attachment if the devices have about the same nanometer-range thickness as the protein layer. Moreover, the longer the protein-coated nanocantilever, the faster the vibration, which could only be explained if the density of antibodies were to increase with increasing lengths, Bashir said. The research group also proved this hypothesis using optical measurements and then worked with Ashraf Alam, a researcher at the Birck Nanotechnology Center and professor of electrical and computer engineering, to develop a mathematical model that describes the behavior.
The information will be essential to properly design future "nanomechanical" sensors that use cantilevers, Bashir said.
Findings are detailed in a research paper appearing online today (Monday, Aug. 28) in Proceedings of the National Academy of Sciences. The paper was authored by Amit K. Gupta, a former Purdue doctoral student working with Bashir and now a postdoctoral researcher at Harvard University; Pradeep R. Nair, a doctoral student in electrical and computer engineering; Demir Akin, research assistant professor of biomedical engineering; Michael Ladisch, Distinguished Professor of Agricultural and Biological Engineering with a joint appointment in the Weldon School of Biomedical Engineering; Steven Broyles, a professor of biochemistry; Alam and Bashir.
The work, funded by the National Institutes of Health, is aimed at developing advanced sensors capable of detecting minute quantities of viruses, bacteria and other contaminants in air and fluids by coating the cantilevers with proteins, including antibodies that attract the contaminants. Such sensors will have applications in areas including environmental-health monitoring in hospitals and homeland security. So-called "lab-on-a-chip" technologies could make it possible to replace bulky lab equipment with miniature sensors, saving time, energy and materials. Thousands of the cantilevers can be fabricated on a 1-square-centimeter chip, Bashir said.
The cantilevers studied in the recent work range in length from a few microns to tens of microns, or millionths of a meter, and are about 20 nanometers thick, which is also roughly the thickness of the antibody coating. A nanometer is a billionth of a meter, or approximately the length of 10 hydrogen atoms strung together.
A cantilever naturally "resonates," or vibrates at a specific frequency, depending on its mass and mechanical properties. The mass changes when contaminants land on the devices, causing them to vibrate at a different "resonant frequency, " which can be quickly detected. Because certain proteins attract only specific contaminants, the change in vibration frequency means a particular contaminant is present.
Ordinarily, when using cantilevers that are on a thickness scale of microns or larger, attaching mass causes the resonant frequency to decrease, which is the opposite of what occurs with the nanoscale-thickness cantilevers. Researchers believe the unexpected behavior is a result of the antibodies being about the same thickness as the ultra-thin nanocantilevers, meaning their vibration is more profoundly affected than a more massive cantilever would be by the attachment of the antibodies.
"The conclusion is that when the attached mass is as thick as the cantilever, then you not only affect the mass but you also affect a key property called the net stiffness constant and the resonant frequency can actually go up," Bashir said.
Gupta measured the cantilever's vibration frequency using an instrument called a laser Doppler vibrometer, which detects changes in the cantilever's velocity as it vibrates. The researchers then treated the antibodies with a fluorescent dye and took images of the proteins on the cantilever's surface, proving that the density increases with longer cantilevers.
Nair and Alam then developed a mathematical model to explain why the density increases as the area of the cantilever rises. The model uses a "diffusion reaction equation" to simulate the antibodies sticking to the cantilever's surface.
Contact: Emil Venere
venere@purdue.edu
765-494-4709
Purdue University

Hydrogen: Fuel for Our Future?

Hydrogen-powered cars like this one may be commonplace in the future.
September 11, 2006


On July 18, BP and GE announced plans to jointly develop up to 15 new hydrogen power plants for generating electricity over the coming decade. The hydrogen will be derived from fossil fuels, including coal and natural gas. While the plants will emit greenhouse gases, the companies will employ carbon capture technologies they claim will reduce carbon dioxide (CO2) emissions by 90 percent. Although the operations will not be pollution-free, some environmentalists welcome the companies’ investment in hydrogen technology as a key development in bringing about a hydrogen economy.
Though often mistaken for an energy source, hydrogen is actually an artificial fuel—like gasoline—that can be used to transport and store energy. Although it can be separated from fossil fuels, its long-term promise lies in its ability to be separated from water through electrolysis, using solar power or other forms of renewable energy. Its most publicized application is in transportation: the hydrogen gas is stored in an on-board tank until combined with oxygen in a fuel cell, where the electrolysis process is essentially reversed, releasing chemical energy via an electrical charge. This electricity can then be used to power electric motors in cars, buses, boats, and other vehicles.
In the short run, fuel cells are also considered a promising source of electricity for some industries and buildings, particularly those that require steady back-up power during blackouts. In this application, hydrogen is most often derived from natural gas and propane, which already have extensive distribution systems in place.
Using fossil fuels to generate hydrogen can result in modestly lower emissions of CO2 and other pollutants than using these fuels as conventional energy sources, though this depends on the efficiency of the technologies involved. In order to get larger reductions, the CO2 must be captured and sequestered, a process that remains experimental and expensive. However, when the hydrogen separation process is based on renewable energy sources, hydrogen use is essentially pollution-free, with the only byproducts being water and heat.
Since 1999, when Iceland announced its plan to become the first hydrogen-based economy in the next 30–40 years, governments and businesses have begun to seriously consider the hydrogen option. In 2000, the small South Pacific island of Vanuatu joined Iceland in making steps towards widespread hydrogen use and deriving 100 percent of its energy from renewable sources. Hawaii, another island rich in renewable resources such as geothermal and wind energy yet still heavily dependent on oil imports, invested in hydrogen research in 2001, hoping to eventually export hydrogen to other states and nations. And California, the United States’ largest gasoline consumer, began developing the world’s first “hydrogen highway” in 2004.
Despite initial enthusiasm, some of these regions are making greater progress than others. Freyr Sverrisson, an independent energy consultant from Iceland, says that so far the Icelandic government has taken little concrete action toward meeting its hydrogen target: it is home to only one hydrogen fueling station, and the country has invested significant funds in the aluminum smelting industry that could have been placed in hydrogen development. By generating a carbon dioxide byproduct, the smelting process is helping Iceland become the world’s fastest growing emitter of CO2. The government is “squandering an opportunity,” Sverrisson says, by choosing to invest in the quick returns of aluminum smelting instead of developing the hydrogen economy with longer-term benefits.
Yet according to Jon Bjorn Skulason, general manager of Icelandic New Energy, the country is just 6–12 months behind the original plan proposed in 1999. In addition to having three operational fuel cell buses and the one fuel cell filling station, Iceland has passed a preemptive law that will eliminate all taxes on hydrogen cars once they begin to be sold domestically. With over 90 percent of citizens in favor of developing a hydrogen economy and continued support for the project from the government and business, Skulason does not foresee any further delays.
California, meanwhile, already boasts 23 hydrogen fueling stations (14 more are slated to be built this year) and has put 137 hydrogen-powered passenger cars and 9 buses on the road, more than any region in the world, according to Chris White of the California Fuel Cell Partnership. Although the partnership is still operating in a “demonstration phase,” notes White, several of its members (many of which are automotive companies) expect to make hydrogen-powered commercial vehicles as early as 2010, and to have showroom cars by 2015. According to White, this is the same way hybrid-electric cars were introduced to the market in the 1990s.
Yet transitioning to a hydrogen economy has raised some concerns. Because hydrogen is odorless and burns with a clear flame, leaks can be difficult to detect, although the gas is so light and disperses so quickly that the chance of an open explosion is considered minimal. (While many associate hydrogen with the 1937 Hindenburg disaster, the explosion of the German airship in fact began with ignition of the blimp’s highly flammable outer covering, not the gas it carried.) Even so, careful engineering is necessary to ensure that hydrogen fuel cell vehicles are safer than gasoline vehicles, according to a 1997 Ford Motor Company study.
“Hydrogen is one of the keys to a new energy economy that relies on solar and wind power rather than fossil fuels,” according to Worldwatch President Chris Flavin. “Private and public investment in hydrogen technology should be increased substantially. But in the next few years, the largest reductions in oil demand and greenhouse gas emissions will come from improved fuel economy and biofuels—both of which are fully competitive today.”
Alana Herro