Crave

While computers continue to get smaller, they're constantly being pushed to do more. Whether they're doubling as a phone, a camera, or an MP3 player, there seems to be no end to the tasks we expect them to carry out. And as always, we say we want them to "do all that stuff and be smaller."

(Credit: IBM)

A limitation of the miniaturization process is that the more computers are asked to do, the more memory they require. One of the computer's basic elements, the transistor, could soon reach its miniaturization limit. The smaller we make transistors, the more susceptible they are to quantum phenomena like electrons tunneling through the barriers between wires. Which, while ticklish for the barrier, can just be really annoying.

This has apparently annoyed researchers at the U.K.'s University of Nottingham, as well, albeit for different reasons. This transistor dilemma has led them to look into the viability of carbon nanotubes to help create fast, cheap, and compact memory that uses little power.

In his laboratory at Tokyo University, researcher Tsuyoshi Sekitani displays a robot hand and an elastic sheet containing carbon nanotubes that conduct electricity.

(Credit: AFP Photo/Yoshikazu Tsuno)

Japanese researchers say they have developed a rubber-like material that's able to conduct electricity, paving the way for robots with stretchable "e-skin" that can feel heat and pressure like humans.

The material, described by Tsuyoshi Sekitani of the University of Tokyo in the journal Science, could be used on curved surfaces or even in moving parts, such as the joints of a robot's arm, the researchers said.

Sekitani's team developed their material using carbon nanotubes, a long stretch of carbon molecules that can conduct electricity. They mixed these into a rubbery polymer to form the basic material. Next, they attached a grid of tiny transistors to the material and put it to the test.

They stretched the sheet of material to nearly double its original size, and it snapped back into place, they said, without disrupting the transistors or ruining the material's conductive properties.

Reuters contributed to this report.

An artificial muscle that can heal itself and recharge an iPod at the same time? Sounds ludicrous, but researchers at the University of California at Los Angeles have developed an electricity-generating muscle that might one day be to used to create walking robots or advanced prosthetics, according to Discovery News.

Qibing Pei, a scientist at UCLA and author of the research that appeared in the January edition of Advanced Materials, said his team developed a lifelike artificial muscle by using carbon nanotubes as electrodes. Unlike other artificial muscles made with metal-based films, this muscle can expand more than 200 percent when applied with electricity, without undergoing failure. When under pressure, the carbon nanotubes have a way of shutting down and preventing the spread of failure to other areas of the muscle so it can continue to work, according to the scientists.

The muscle is also energy-efficient, conserving 70 percent of the energy put into it, the scientists said. That electrical current can be used to power other electronics like an iPhone, or can even be used to generate ocean waves. Scientists in Japan charge batteries from ocean waves using the same idea, according to Discovery.

A loosely packed "carpet" of carbon nanotubes is the darkest material ever made, according to researchers from Rice University and Rensselaer Polytechnic Institute.

The carpet consists of nanotubes--hollow, honeycombed tubes made from carbon atoms-- standing vertically. Instead of being tightly packed together, the researchers went for a low density arrangement, complete with spaces and gaps, sort of like a box of dried spaghetti. Light striking the nanotubes as well as the gaps gets absorbed. When light gets absorbed, black (the absence of light) results. The nanotubes were also specially manufactured to have a more random arrangement of atoms, further reducing reflectivity. (Again, think of trying to look into a box of spaghetti. Not easy.)

The nanocarpet is in the middle. Former record holder to the left.

(Credit: RPI)

This resulted in a material that reflects only 0.045 percent of the light that strikes it. (Put another way, 99.955 percent of the light that hits it gets absorbed.)

Conventional black paint reflects 100 times more light. The previous record holder for darkness, a nickel-phophorus alloy pitted with light-trapping craters, reflected four times as much light.

So what good is this? Will goths use it for Halloween costumes? The material could help in advancing solar cells, which trap sunlight and convert it to energy. It could also one day be used by astronomers.

Side shot of the nanocarpet

(Credit: RPI)

Chalk another one up for carbon nanotubes, the reigning celebrity in the advanced materials world. Many believe the tubes will be used to deliver medicine in humans, build bridges, and conduct electricity inside of semiconductors someday.

"It is a fascinating technology, and this discovery will allow us to increase the absorption efficiency of light as well as the overall radiation-to-electricity efficiency of solar energy conservation," said Rensselaer physicist Shawn-Yu Lin in a prepared statement. He's the lead co-author of the study. "The key to this discovery was finding how to create a long, extremely porous vertically-aligned carbon nanotube array with certain surface randomness, therefore minimizing reflection and maximizing absorption simultaneously."

University of California at Berkeley's nanoradio might be a 100 billion times smaller than the first commercial radios, but it plays the hits that never die.

Alex Zettl, a professor of physics at the university, has made a radio out of a single carbon nanotube that's about 10,000 times thinner than a human hair. It runs on batteries and you need headphones to use it, but it tunes in stations on the FM dial.

Zettl and his team last year received their first FM broadcast, which turned out to be "Layla" from Derek and the Dominoes. They also caught "Good Vibrations." In homage to the 100th anniversary of the first voice and music transmission, they transmitted (and tuned in to) a recording of "Largo," from the Handel opera Xerxes. It was the first successful radio transmission of music in 1906.

The nanotube serves as the antenna, tuner, amplifier, and demodulator in the radio. In an ordinary radio, these are all separate components. The nanotube vibrates thousands to millions of times per second in tune with the radio wave.

Carbon nanotubes are the miracle material of the chemistry world. Stronger than steel yet very light, nanotubes can also transmit electricity faster than metals as well as emit light. Scientists speculate that nanotubes one day could be incorporated into silicon chips, power lines, medicines, bridges, and aircraft parts. Nanotubes are essentially cylinders made completely from carbon atoms; the incredibly strong bonds that can be formed between carbon atoms are what give nanotubes their unusual properties.

Right now, though, nanotubes are mostly used to make things like tennis rackets and car panels stronger without adding weight.

"The nanotube radio may lead to radical new applications, such as radio-controlled devices small enough to exist in a human's bloodstream," wrote Zettl and his team in a paper that was released online Wednesday and will be published November 6 in Nano Letters.

The nanoradio could also be used to measure the mass of atoms.

Researchers at Rensselaer Polytechnic Institute have come up with a way to detect potential structural problems with fighter planes while in flight, and in some cases repair them.

Carbon nanotubes in epoxy

(Credit: RPI)

The technique, which is still experimental, involves applying an epoxy later infused with a wire grid and carbon nanotubes onto a wing or other structure. The epoxy is similar to the materials currently used to make fighter plane components. The wire grid and the nanotubes function as a communication network. Mechanics (or a computer) will shoot an electrical charge through the structure and measure how long it takes an electrical charge to go from two selected points.

If there is a crack in the structure, the crack will create electrical resistance. In that case, the signal will have to travel a longer distance to get around the crack. The extra time required to get from point A to point B serves as a signal that a potential problem exists. The picture shows carbon nanotubes randomly dispersed in an epoxy.

The cracks can also be repaired, depending on the material the wing is made of and other factors. When a crack is detected, voltage to the carbon nanotubes can be increased. This generates heat, which melts the epoxy that fills the crack in. In certain circumstances, the repaired wing will regain up to 70 percent of its original strength, according to RPI. That should keep you from plunging to your death.

The beauty of this method is that the carbon nanotubes are everywhere. The sensors are actually an integral part of the structure, which allows you to monitor any part of the structure," said Nikhil A. Koratkar, an associate professor in Rensselaer's Department of Mechanical, Aerospace & Nuclear Engineering, in a prepared statement. Koratkar was the principal investigator on the project.

A more detailed paper was published this week in Applied Physics Letters.

Nanotubes, which are stronger than steel, can also add structural integrity, depending on how they are integrated into a structure. General Motors puts multiwalled nanotubes into some car parts.

Angela Belcher at MIT (and co-founder of Cambrios Technologies) is working on a different technology for detecting flaws in metal aircraft parts. She is trying to develop genetically engineered microorganisms that will secrete proteins that will attach to specific metal alloys. Smear it on, the theory goes, and the luminescent protein will stick to areas undergoing abnormal amounts of stress.

Companies have been trying to figure out how to use carbon nanotubes in electronics. Batteries may be the answer, say researchers at Rensselaer Polytechnic Institute.

The device is a piece of paper infused with carbon nanotubes and a salt, which serves as an electrolyte. Because it stores energy and conducts it, the device can act like a battery.

A number of corporate labs and universities have come up with flexible batteries in the past. Power Paper from Israel makes a flexible battery printed on polymers that relies on zinc as an electrolyte. It sells it to the cosmetics industry. Japan Inc. also has trotted out a lot of prototypes. Still, these things haven't gone commercial so any advance is welcome.

You can bend me, but not break me

(Credit: RPI)

As an added bonus, the RPI device can deliver power over a long period of time, like a battery, or lots of power in a short burst, like a capacitor.

It's essentially a regular piece of paper, but it's made in a very intelligent way, said Robert Linhardt, the Ann and John H. Broadbent '59 Senior Constellation Professor of Biocatalysis and Metabolic Engineering at Rensselaer, in a prepared statement.

Carbon nanotubes have been the celebrity of the material science circuit for the past decade or so. Among their other attributes, nanotubes conduct electricity more efficiently than metal. They are also flexible, although stronger than steel. Right now, they are somewhat expensive, but mass manufacturing will drop the price. The only element is carbon, after all.

Conceivably, these paper batteries could be stacked up in a device to give it power. They could be used to insert electronic computers into luggage tags or greeting cards or into larger devices.

But it is a long road. Battery technology, and the adoption by equipment makers, takes a long time.