NEWS : TECH (NFPC)

Lens Converts Light Into Sound

By Dexter Johnson, IEEE Spectrum

The researcher used sound waves to drill holes into a confetti-sized artificial kidney stone. Credit: Jay Gou, University of Michigan

Remember how Leonard McCoy performed surgery in Star Trek? He would wave a device over the patient. The outer layers of the skin didn't need not be cut, even when operating on internal organs, and the precision of 23rd-century instrument reached down to the level of individual cells.

Well, we already have a bit of that in the 21st. Research at the University of Michigan, led by Jay Gou, has developed a device that employs a carbon-nanotube-coated lens capable of converting light into tightly focused sound waves. The new ultrasound therapeutic tool that reaches new levels of precision -- its high-amplitude sound waves are able to target an object with dimensions of 75 by 400 micrometers.

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"A major drawback of current strongly focused ultrasound technology is a bulky focal spot, which is on the order of several millimeters," says Hyoung Won Baac, who worked on the project as a doctoral student and is now a research fellow at Harvard Medical School, in a press release. "A few centimeters is typical. Therefore, it can be difficult to treat tissue objects in a high-precision manner, for targeting delicate vasculature, thin tissue layer and cellular texture. We can enhance the focal accuracy 100-fold."

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The research, which was published in the journal Nature (“Carbon-Nanotube Optoacoustic Lens for Focused Ultrasound Generation and High-Precision Targeted Therapy”), coated a concave lens with a nano-composite film of carbon nanotubes (CNTs) and elastomeric polymer. A pulsed laser source is aimed at the lens. The CNTs absorb the light coming from the laser which generates heat. The polymer expands from the heat being generated by the CNTs. This rapid expansion of the polymer amplifies the signal.

The CNT-coated lens when coupled with a pulsed laser is capable of extreme optoacoustic pressures of >50 megapascals. This unprecedented level of pressure results in both shock effects and cavitation without heat being used on the target.

While recent research in sharpening sound waves -- at least for imaging devices -- has led to exotic acoustic hyperlenses made from metamaterials, the underlying technique behind this device’s conversion of light to sound goes back to at least Thomas Edison. But to date the sound projected from devices employing these techniques was not strong enough to prove useful in medical applications.

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"We believe this could be used as an invisible knife for noninvasive surgery," Guo says in a university press release. "Nothing pokes into your body, just the ultrasound beam. And it is so tightly focused, you can disrupt individual cells."

It may still be a while before your surgeon is able to wave a wand over you and send you back to your hospital room without a scar -- the technology hasn't even been tested on animals yet -- but we may get there well before the 23rd century.

This article originally appeared on IEEE Spectrum as Nanoparticle Coated Lens Converts Light into Sound for Precise Non-invasive Surgery

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First All-Carbon Solar Cell: DNews Nugget

First All-Carbon Solar Cell: Nearly everyone is familiar with what a rooftop solar panel looks like. It's a big, rigid square panel. But now scientists have developed a thin film prototype made entirely of carbon that can be coated from liquid. "Every component in our solar cell, from top to bottom, is made of carbon materials," said Stanford graduate student Michael Vosgueritchian, who was on the research team. "Other groups have reported making all-carbon solar cells, but they were referring to just the active layer in the middle, not the electrodes."

Since carbon is abundant, the material is cheap and because the process involves coating, the manufacturing is inexpensive. Right now, the scientists are working on making the solar cells more efficient, but in the future cheap, flexible solar cells made from carbon could be coated on everything from buildings to cars to generate power. via Physorg.com

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Draw Carbon Nanotubes With A Pencil

We've seen how easily carbon nanotubes can detect harmful gases. What's not so easy is building the sensors. Methods are often hazardous and unfit for large-scale production.

However, some chemists from the Massachusetts Institute of Technology (MIT) have come up with a new fabrication method -- one that's as easy as drawing a line on a piece of paper.

Katherine Mirica, an MIT postdoc, designed a new type of lead that can be used in an ordinary mechanical pencil, where graphite is replaced with a compressed powder of carbon nanotubes. With a few clicks from a thumb, sensors can be drawn on any paper surface.

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To create their sensors, researchers drew a line of carbon nanotubes on a piece of paper stamped with small, gold electrodes. Next, they ran an electrical current through the carbon nanotube, which acts as a resistor. If the current is altered, that indicates a gas has bound to the carbon nanotubes.

The sensor detects trace amounts of ammonia gas, an industrial hazard and key ingredient in explosives. And the devices can be revamped to to detect almost any type of gas, says Timothy Swager, the John D. MacArthur Professor of Chemistry, who led the project.

BLOG: Paper-Based Sensor Detects Explosives

"The beauty of this is we can start doing all sorts of chemically specific functionalized materials,” Swager said in a university news release. "We think we can make sensors for almost anything that's volatile."

Researchers said the two most significant advantages of the method are that it's inexpensive and the "pencil lead" is exceptionally stable. The team published their findings in the journal Angewandte Chemie.

via Inhabitat

Credit: Jan Schnorr

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Nanoscience Explained: Gotta-See Video

Nanoscience is small science with huge possibility. "Nano-" is a prefix that means "a billionth." Basically just recognize that when we talk about nanoparticles, nanobots, nanoscience, nanotubes or nanotech, this stuff is REALLY tiny.

Nanoscience has been around a while, but people aren't necessarily aware of what research and applications are being explored. Take a quick tour of nanoscience here and learn enough to make a few declarative statements at your next cocktail party. via YouTube

Want to recommend a video? Tweet it to @Discovery_News with the hashtag #GottaSeeVideos.

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Geoengineering Soaring To New Heights

I come from a pasty Norwegian breed. In my younger, devil-may-care years, I used to scoff at wearing sunscreen with the belief that the quickest way to skin cancer a bronzed bod was roasting myself at the beach without a drop of SPF in sight.

Not any more. I've read the reports and even witnessed my dad, who has a similar complexion, receive skin test results that came back malignant. Now I'm a liberal sunscreen applier when I go out. Plus, sunscreen makes you smell like you just came from the beach, and I like that. It's my new cologne.

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In some ways, our planet is of a pasty breed and needs adequate protection from the sun, too. Many scientists say our planet is getting hotter, compliments of us industrious folks who call Earth home.

Here in Missouri, the grass is brown and the leaves on the trees are wilted. The USDA has declared every county in the state as disaster area because of the drought. Just a random old hot-and-dry summer or the consequences of human-induced climate change?

Well, a couple of Harvard engineers aren't waiting around for your opinion. David Keith and James Anderson are preparing to spray thousands of tons of sun-reflecting sulphate aerosols into the sky over Fort Sumner, New Mexico. Why? They believe the particles will reflect the sun's rays back into space and help lower the Earth's temperature.

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They plan to do so by using a balloon flying 80,000 feet above the Fort Sumner. The geoengineering project aims to mimic the effects of volcanoes spewing sulphuric ash into the air.

Keith says the project could be an inexpensive way to slow down climate change, however other scientists warn that his methods could have dire effects on the planet's weather systems and food supplies. Environmentalists fear Keith's method is merely a stopgap that undermines efforts to accurately fight climate change by reducing carbon emissions.

The experiment will take place in a year and see the release of tens or hundreds of kilograms of particles that, besides measuring impacts on ozone chemistry, will also find ways to make the sulphate aerosols the correct size.

"The objective is not to alter the climate, but simply to probe the processes at a micro scale," Keith told the Guardian. "The direct risk is very small.

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However, Pat Mooney, executive director of the technology watchdog ETC Group, begs to differ:

"Impacts include the potential for further damage to the ozone layer, and disruption of rainfall, particularly in tropical and subtropical regions – potentially threatening the food supplies of billions of people. It will do nothing to decrease levels of greenhouse gases in the atmosphere or halt ocean acidification. And solar geoengineering is likely to increase the risk of climate-related international conflict -- given that the modelling to date shows it poses greater risks to the global south."

What say you? Let the balloon fly or pop it with a BB gun before lifts off?

via the Guardian

Credit: NASA/Roger Ressmeyer/CORBIS

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Solar Cell Absorbs Invisible Light

A new kind of solar cell made from carbon harvests sunlight that other cells can't see. The technology could greatly boost the efficiency of solar panels and help bring the down the price of solar panels.

The invisible sunlight being captured is the near-infrared part of the spectrum, which makes up a whopping 40 percent of the wavelengths of light beaming down from the sun. Most solar cells, made from silicon or special plastics, harvest visible light, the wavelengths of light we see in a rainbow. But so far, that's not very efficient.

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Looking for a way to improve the efficiency of solar cells, a research team at the Massachusetts Institute of Technology turned to carbon nanotubes and C60, otherwise known as buckyballs. Carbon solar cells absorb energy from the near-infrared wavelengths of without heating up, the way that silicon cell do.

Previous attempts at making photovoltaic cells of carbon have been tried before, but the resulting cells required a layer of polymer to hold the carbon nanotubes in place. The MIT team's cell is stable when exposed to air. Layers of carbon nanotubes and buckyballs are also transparent. That means one can put a layer of the carbon on top of an ordinary solar cell and boost the energy output.

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There are still some kinks to work out. One is mass-producing the carbon cells, as it's not always easy to get the kind of pure carbon nanotubes necessary. Michael Strano, a professor of chemical engineering at MIT and senior author of the paper, told Discovery News that his lab has licensed a method to a private company to address that. Another is the energy efficiency. At 0.1 percent it's only a hundredth of a typical cell.

"The morphology is not ideal," Strano said. He noted that the carbon nanotubes and buckyballs are distributed randomly on the cell surface, with the bockyballs filling the gaps between tubes and sometimes sitting on top of them. "In future work, we have to better organize these two materials."

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But even a low efficiency could make a big difference. The sun typically sends about 4-6 kilowatt-hours per square meter per day onto the United States. About 43 percent of that energy is in the near-infrared and totally wasted. If carbon solar cells were added to the mix, about half of what is usually just lost could be harvested, Strano said. Even a fraction of that added to a typical solar cell would be an improvement. RIshabh Jain, the lead author of the paper, said the team hopes to reach the 20 percent efficiency mark of commercial cells. 

The work was published in the journal Advanced Materials.

Photo: An atomic-force microscope image of a layer of single-walled carbon nanotubes deposited on a silicon surface. Individual nanotubes can be seen in the image. Credit: MIT / Rishabh Jain

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Crumpled Electronics Keep Working

Engineers are developing electronics can be bent, folded, stretched and even adhere like a second skin. It was only a matter of time before someone took a look at crumpling them too.

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Shinya Aikawa and his colleagues from the University of Tokyo and the Tokyo University of Science have built transistors out of carbon nanotubes, which are thin but strong and flexible at the same time. The transistors can be folded to the point where the bend's radius is only a single millimeter -- not quite a complete fold, but very close. It's the equivalent of folding it around the edge of a paper clip. As an added bonus the circuits were transparent.

The team built a field effect transistor (FET) entirely out of carbon nanotubes. Previously if you wanted a flexible and see-through FET you needed to use gold or indium tin oxide as electrodes. But gold isn't very transparent and indium tin oxide is brittle. Another innovation was using a thin substrate of polyvinyl alcohol, which is used in some glues as a thickening agent.

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What they got was a transistor only 15 micrometers thick. The transistor did lose some performance after being crumpled about 100 times. That might be because some of the carbon nanotubes break down. But even so, it means there's potential for sticking electronics on surfaces where they don't usually do well – perhaps in something like a band-aid, which flexes a lot.

Image: American Institute of Physics

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Space Elevator, Going Up

Ever ridden in one of those elevators where a softly feminine, robotic voice alerts you to what floor you're going to next? Yeah, me neither. But if I had, wouldn't it be cool if the voice said this instead: Going up. Next floor, outer space.

Well, that dream may be closer than I think, as long as I manage to make it to my 70th birthday.

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According to The Daily Yomiuri, Tokyo construction company, Obayashi Corporation, hopes to erect a space elevator by 2050. As a doff of the cap to our British readers, the space lift would ferry passengers and cargo along a carbon nanotube ribbon from a terrestrial terminal to a spaceport nearly a quarter of the way to the moon.

How is this possible? Well, on paper, here's what's on tap:

At the end of a 59,652-mile-long, carbon-nanotube cable, there would be a counterweight floating in space and anchoring the assembly connected to the ground terminal. Passengers would travel from terra firma to a spaceport research center equipped with residential facilities located 22,369 miles above the Earth's surface.

Interested in beaming yourself up? Well, make sure you pack your toothbrush and an few changes of clothes because even though the elevator will zoom up the ribbon at 124 miles per hour, it's still going to take a week to get there. Those who have ever undertaken a cross-country trip on a Greyhound bus know how pleasant a journey that can be.

Obayashi is keeping mum about the estimated cost of the project, but once it's off the ground, the company hopes to shuttle 30 passengers at a time along the cable, potentially with magnetic linear motors.

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No location has been revealed yet, but because the assembly would rely on centrifugal force to keep the ribbon taut, the base station needs to be located near the equator. Here's looking at you, Pontianak, Indonesia.

An ambitious project indeed, sure to have many ups and downs.

via Gizmag

Credit: NASA (top); Obayashi Corp. (left)

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When Will Carbon Nanotubes Save The World?

Carbon nanotubes have been around for decades, but they've yet to make a significant impact among the public at large. What's the deal? When are these light, strong microscopic filaments going to change the world? Some would say they already have. Here are a couple new ways researchers are using carbon nanotubes to make our world more awesome.

In a computer system, if one copper wire fails to transmit the electrons the whole system can fail. While most research is focused on producing carbon nanotubes efficiently and cheaply, researchers at National Institute of Standards and Technology (NIST) are exploring their actual use in technological application.

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As electronics get smaller, manufacturers search for ways to save space. Nanotubes are a possible way to miniaturize the connections between components. Aside from their small size, the filaments themselves "offer big promise in a small package," said Science Daily, "These tiny cylinders of carbon molecules theoretically can carry 1,000 times more electric current than a metal conductor of the same size." 

Science Daily continues, "it's easy to imagine carbon nanotubes replacing copper wiring in future nanoscale electronics." However, Thomas Edison tried carbon filaments while working on the lightbulb, and though they were not nano-sized they burned out too quickly. Unfortunately for the researchers trying to replace copper, their nano brothers experienced the same problem.

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"The common link is that we really need to study the interfaces," says Mark Strus, a NIST postdoctoral researcher. The interfaces are the connections between nanotubes as well as the connections between nanotubes and other metals.

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Exploration in this area is sparsely researched, and the results will help press the nanotubes into electronics service once their creation is affordable.

Unfortunately, the researchers' determinations were not promising for the replacement of copper in chips because as "metal electrodes fail -- the edges recede and clump -- when currents rise above a certain threshold. The circuits failed in about 40 hours," said Science Daily.

Though the nanotubes seem ill-fitted for computer chips, Mark Strus, another NIST postdoctoral researcher, said, "Carbon nanotube networks may not be the replacement for copper in logic or memory devices, but they may turn out to be interconnects for flexible electronic displays or photovoltaics."

Outside of the NIST project, other researchers are looking for nanotubes to function as more efficient biosensors.

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Biosensors use electrodes coated with enzymes to "sense" certain compounds. When the compounds are present the enzymes react, creating a measurable electrical signal. Current systems work, if imperfectly, and nanotubes might be able to revolutionize this field too. Scientists at Purdue University are exploring carbon nanotubes for these new biosensors.

To make the nanotubes compatible with the process, they must first make them compatible with water. To solve the problem, professors Marshall Porterfield and Jong Hyun Choi created synthetic DNA that attaches the nanotubes in a solution.

"In the future, we will be able to create a DNA sequence that is complementary to the carbon nanotubes and is compatible with specific biosensor enzymes for the many different compounds we want to measure," Porterfield said. Choi continued, "Once the carbon nanotubes are in a solution, you only have to place the electrode into the solution and charge it. The carbon nanotubes will then coat the surface,"

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The floating tubes will indicate the presence of the specific enzyme which can be measured and reported externally.The sensor described in the findings is designed for glucose, however, the technology can be adapted for other compounds.

"You could mass produce these sensors for diabetes, for example, for insulin management for diabetic patients," Porterfield said.

While nanotubes are still in the research phase, they've come a long way from their discovery and mass creation. Once they can be cheaply produced, research like this will help us press them into service around the scientific and technological worlds.

Source: PhysOrg, Science Daily
Image: Corbis

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Paper-Based Sensor Detects Explosives

The days of ye olde ink-jet printer only being able to print letters and images on paper are long gone. Today's printers can create just about anything you can imagine -- everything from bikinis and skin, to car parts and scallop nuggets in the shape of a space ship.

So it comes as no surprise that some researchers from the Georgia Institute of Technology have created a prototype wireless sensor that can detect trace amounts of ammonia, often a key ingredient in explosives. Oh yeah, and they used a printer to do so.

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Using standard ink-jet technology, the wireless, ammonia-sensing prototype was printed on paper or a paper-like material. The sensing component utilizes carbon nanotubes which researchers say offer dramatically improved sensitivity over previous sensors. The lightweight antenna, which communicates this sensor information, was printed on photographic paper.

"This prototype represents a significant step toward producing an integrated wireless system for explosives detection,” the project's lead research scientist, Krishna Naishadham, said in a press release. “It incorporates a sensor and a communications device in a small, low-cost package that could operate almost anywhere.”

Naishadham said the device is an improvement on other hazardous gas sensors which are expensive, consume more power, require human intervention and often don't operate at ambient temperatures.

Manos Tentzeris, a professor at Georgia Tech’s School of Electrical and Computer Engineering, designed the ink-jet techniques used in the project. Tentzeris said the secret to successfully printing the device's components, circuits and antennas lies in using "inks" that contain silver nanoparticles in an emulsion that the printer can deposit at temperatures of around 212 degrees Fahrenheit.

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“Ink-jet printing is low-cost and convenient compared to other technologies such as wet etching,” Tentzeris said. “Using the proper inks, a printer can be used almost anywhere to produce custom circuits and components, replacing traditional clean-room approaches.”

But the paper-based, wireless prototype's foremost feature is that it offers "standoff detection", meaning that explosives can be detected from a distance without endangering human lives.

“We are focusing on providing standoff detection for those engaged in military or humanitarian missions and other hazardous situations,” Naishadham said. “We believe that it will be possible, and cost-effective, to deploy large numbers of these detectors on vehicles or robots throughout a military engagement zone.”

[Via NewsWise]

Image: Georgia Tech

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