Archive for December, 2011

Self-healing electronics could work longer and reduce waste

December 24, 2011

When one tiny circuit within an integrated chip cracks or fails, the whole chip – or even the whole device – is a loss. But what if it could fix itself, and fix itself so fast that the user never even knew there was a problem?

Engineers at the University of Illinois have developed a self-healing system that restores electrical conductivity to a cracked circuit in less time than it takes to blink. Led by aerospace engineering professor Scott White and materials science and engineering professor Nancy Sottos, the researchers published their results in the journal Advanced Materials.

“It simplifies the system,” said chemistry professor Jeffrey Moore, a co-author of the paper. “Rather than having to build in redundancies or to build in a sensory diagnostics system, this material is designed to take care of the problem itself.”

As electronic devices are evolving to perform more sophisticated tasks, manufacturers are packing as much density onto a chip as possible. However, such density compounds reliability problems, such as failure stemming from fluctuating temperature cycles as the device operates or fatigue. A failure at any point in the circuit can shut down the whole device.

“In general there’s not much avenue for manual repair,” Sottos said. “Sometimes you just can’t get to the inside. In a multilayer integrated circuit, there’s no opening it up. Normally you just replace the whole chip. It’s true for a battery too. You can’t pull a battery apart and try to find the source of the failure.”

Most consumer devices are meant to be replaced fairly regularly, adding to electronic waste issues, but in many important applications – such as instruments or vehicles for space or military functions – electrical failures can’t be replaced or repaired.

The Illinois team previously developed a system for self-healing polymer materials and decided to adapt their technique for conductive systems. They dispersed tiny microcapsules, as small as 10 microns in diameter, on top of a gold line functioning as a circuit. As a crack propagates, the microcapsules break open and release the liquid metal contained inside. The liquid metal fills in the gap in the circuit, restoring electrical flow.

Click to enlarge.

“What’s really cool about this paper is it’s the first example of taking the microcapsule-based healing approach and applying it to a new function,” White said. “Everything prior to this has been on structural repair. This is on conductivity restoration. It shows the concept translates to other things as well.”

A failure interrupts current for mere microseconds as the liquid metal immediately fills the crack. The researchers demonstrated that 90 percent of their samples healed to 99 percent of original conductivity, even with a small amount of microcapsules.

The self-healing system also has the advantages of being localised and autonomous. Only the microcapsules that a crack intercepts are opened, so repair only takes place at the point of damage. Furthermore, it requires no human intervention or diagnostics, a boon for applications where accessing a break for repair is impossible, such as a battery, or finding the source of a failure is difficult, such as an air- or spacecraft.

“In an aircraft, especially a defense-based aircraft, there are miles and miles of conductive wire,” Sottos said. “You don’t often know where the break occurs. The autonomous part is nice – it knows where it broke, even if we don’t.”

Next, the researchers plan to further refine their system and explore other possibilities for using microcapsules to control conductivity. They are particularly interested in applying the microcapsule-based self-healing system to batteries, improving their safety and longevity.


Paint-on solar cells developed

December 23, 2011

Imagine if the next coat of paint you put on the outside of your home generated electricity from light — electricity that could be used to power the appliances and equipment on the inside.

Researchers at the University of Notre Dame have taken a major step towards this vision by creating inexpensive “solar paint” that uses semiconducting nano-particles to produce energy.

“We want to do something transformative, to move beyond current silicon-based solar technology,” says Professor Prashant V. Kamat, an investigator in Notre Dame’s Center for Nano Science and Technology (NDnano), who leads the research.

“By incorporating power-producing nanoparticles, called quantum dots, into a spreadable compound, we’ve made a one-coat solar paint that can be applied to any conductive surface without special equipment.”

Photo Credit: ACS Nano

The team’s search for the new material, described in the journal ACS Nano, centered on nano-sized particles of titanium dioxide, which were coated with either cadmium sulfide or cadmium selenide. The particles were then suspended in a water-alcohol mixture to create a paste.

When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity.

“The best light-to-energy conversion efficiency we’ve reached so far is 1 percent, which is well behind the usual 10 to 15 percent efficiency of commercial silicon solar cells,” explains Kamat.

“But this paint can be made cheaply and in large quantities. If we can improve the efficiency somewhat, we may be able to make a real difference in meeting energy needs in the future.”

“That’s why we’ve christened the new paint, Sun-Believable,” he adds.

Kamat and his team also plan to study ways to improve the stability of the new material.

Self-cleaning clothes

December 20, 2011

Chinese scientists have developed a special nano-particle coating. When applied to cotton, it causes the fabric to clean itself and remove odours if exposed to sunlight.

The alcohol-based compound is made with titanium dioxide. This is known to be an “excellent catalyst in the degradation of organic pollutants.” It breaks down dirt and kills microbes when exposed to some types of light.

Self-cleaning fabrics have been made in the past, but they only worked if exposed to ultraviolet rays. This new fabric cleans itself in the presence of ordinary sunlight.

The researchers say the method is cheap, non-toxic and ecologically friendly. Retail experts say the innovation could prove popular with retailers due to rising demand for “functional clothing”. The nano-particles remain embedded after washing and drying.

More information can be found in Applied Materials and Interfaces.

LEDs offer brighter future

December 19, 2011

Light-emitting diodes (LEDs) have for many years been used as indicators such as red standby dots on TVs. At first, they were available only as a red light source, and their output was too low for general illumination. As the technology developed, other colours became available and the lamps became brighter, so LEDs found other roles in a wide range of appliances and equipment.

Now, a new study by the UK’s Energy Saving Trust has shown that LED technology can dramatically improve the brightness, colour and distribution of lighting in social housing communal areas.

Not only that, but it can deliver huge energy savings (up to 90%), and reduce long-term costs and maintenance, while making residents feel safer.

Credit: The Energy Saving Trust

The study measured the performance of 4,250 LED light fittings installed at 35 sites. The authors of the report calculated that the LED fittings saved over 3.4 million kilowatt hours (kWh) each year when compared with the previous systems – equivalent to lighting 5,800 average UK homes for a year with traditional lighting.

Residents commented that their buildings felt safer, more secure and more pleasant because they were better illuminated. The light was fresher, brighter and more like daylight.

With spiralling energy prices, the high efficiency of LED lamps will make them a very attractive investment in the future. It is predicted that the technology will dominate the commercial and domestic lighting markets by 2015.

You can download the full report at the Energy Saving Trust website here: (PDF).

Credit: The Energy Saving Trust

Global warming news

December 15, 2011

Worrying news from the Arctic, where a team of Russian scientists have been conducting a survey of the East Siberian Arctic Shelf. They report seeing plumes of methane – “continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter” – bubbling to the surface.

There are hundreds of millions of tons of methane gas locked away beneath the Arctic permafrost and seabed. This particular greenhouse gas is over 20 times more effective at trapping heat than carbon dioxide.

As global average temperatures continue to rise, more and more ice is disappearing from the Arctic, which is the fastest warming area of the planet. If the Siberian permafrost continues to melt, vast amounts of trapped methane could be suddenly belched into the atmosphere – leading to abrupt, severe and possibly irreversible climate change.

Read more in The Independent.

Capturing the speed of light on camera: 1 trillion frames per second

December 15, 2011

By using optical equipment in a new and totally unexpected way, MIT researchers have created an imaging system that makes light appear slow. The system acquires visual data at the rate of one trillion exposures per second, or about 40 billion times faster than a typical video camera. That’s fast enough to produce a slow-motion film of a light beam passing through a one-litre bottle, bouncing off the cap and reflecting back to the bottle’s bottom.

Direct recording of light is impossible at that speed, so the camera takes millions of repeated scans to recreate each image. Because the imaging system requires multiple passes to produce its videos, this means it can only record events that are precisely repeatable.

Despite this drawback, the team hopes the technique could be used to understand a range of ultra-fast processes, to analyse faults and material properties, or in medical imaging, e.g. ultrasound with light. In addition, the photon path analysis will allow new forms of computational photography, such as rendering and re-lighting photos using computer graphics techniques.

One of the system’s developers, Andreas Velten, calls it the “ultimate” in slow motion: “There’s nothing in the universe that looks fast to this camera,” he says.

For more info about this process – known as “femto photography” – see the MIT website.

Aldebaran Robotics launches a new generation of its humanoid robot

December 11, 2011

Aldebaran Robotics has released the latest version of its NAO robot — NAO Next Gen – an autonomous, programmable humanoid robot. Headquartered in Paris, this French startup company has already had success with earlier models. The first prototype was developed in 2005, with a finalised version being used in 2008 for that year’s Robot Soccer World Cup, an international robotics competition. Since then, over 2,000 units have been sold worldwide.

This latest generation has numerous upgrades, thanks to increased computing power, which includes a 1.6 GHz Intel Atom processor. It now features a higher level of interaction, more accuracy, faster and more reliable “Nuance” voice recognition, smart torque control, improved walking algorithms and measures to cut down on unwanted collisions.

When listening to human speech, it has a new functionality called “word spotting”, which is capable of isolating and interpreting a specific word within a sentence or conversation. It also has two HD cameras, attached to a field-programmable gate array (FPGA). This setup allows simultaneous reception of two video streams, significantly increasing speed and performance in face-and-object recognition, even under poor lighting conditions.

As before, the $15,000 robot is aimed squarely at researchers, developers and universities. However, a version for use by the general public is to be launched in late 2012.

For more information, including a video, see the official website:

NAO Next Gen. Credit: Aldebaran Robotics

Carving at the Nanoscale

December 9, 2011

Researchers at the Catalan Institute of Nanotechnology (ICN) have demonstrated a new method for producing a wide variety of complex, hollow nanoparticles. The work, published this week in Science, applies well-known processes of corrosion in a novel manner to produce highly complex, cage-like nano-scale structures. These could have potential applications in fields from medicine to industrial processing.

A common theme in nanotechnology research is the recycling of “old” processes that were once applied crudely on larger bulk materials, but which can now be applied to nano-sized structures with extreme precision, using new instruments and knowledge.

After several years of research, scientists at ICN have refined methods based on traditional corrosion techniques, including the galvanic effect. They show that these methods, which are far more aggressive at the nano-scale than in bulk materials (due to the higher surface area of nanostructures), can provide interesting pathways for the production of new and exotic materials.

By making simple changes in the chemical environment, it is possible to tightly control the reaction and diffusion processes at room temperatures – allowing for high yields and high consistency in form and structure. This should make the processes particularly attractive for commercial applications as they are easily adapted to industrial scales.

A wide range of structures can be formed – including open boxes, bimetallic and trimetallic double-walled open boxes with pores, multiwalled/multichamber boxes, double-walled, porous and multichamber nanotubes, nanoframes, noble metal fullerenes, and many others.

Aside from their intrinsic beauty, these nanostructures will provide new options for drug delivery, chemical sampling, detoxification, catalysis and even structural components for nano-scale robots.

The most Earth-like planet discovered so far

December 6, 2011

NASA’s Kepler mission has confirmed its first planet in the “habitable zone,” the region where liquid water could exist on a planet’s surface. Kepler has also discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets.

The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our own sun. The planet is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding truly Earth-like planets. In the absence of atmosphere, the equilibrium temperature would be around -11°C (12°F). If the greenhouse effect caused by the atmosphere is Earth-like, this would correspond to an average surface temperature of approximately 22°C (72°F).

Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Two other small planets orbiting stars smaller and cooler than our sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars.

“This is a major milestone on the road to finding Earth’s twin,” said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Kepler’s results continue to demonstrate the importance of NASA’s science missions, which aim to answer some of the biggest questions about our place in the universe.”

Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or “transit,” the stars. Kepler requires at least three transits to verify a signal as a planet.

“Fortune smiled upon us with the detection of this planet,” said William Borucki, Kepler principal investigator at NASA Ames Research Center in California, who led the team that discovered Kepler-22b. “The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season.”

The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on candidates the spacecraft finds. The star field that Kepler observes, in the constellations Cygnus and Lyra, can only be seen from ground-based observatories in spring through early autumn. The data from these other observations help determine which candidates can be validated as planets.

Kepler-22b is located 600 light-years away. While the planet is 2.4 times larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet’s host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.

Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed. This milestone will be published in The Astrophysical Journal.

Image credit: NASA/Ames/JPL-Caltech

The Kepler team is hosting its inaugural science conference at Ames this month, announcing 1,094 new planet candidate discoveries. Since the last catalogue was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326. Of these, 207 are approximately Earth-sized, 680 are super Earth-sized, 1,181 are Neptune-sized, 203 are Jupiter-sized and 55 are larger than Jupiter. The findings – based on observations conducted from May 2009 to September 2010 – show a dramatic increase in the numbers of smaller-size planet candidates.

Kepler observed many large planets in small orbits early in its mission, which were reflected in the February data release. Having had more time to observe three transits of planets with longer orbital periods, the new data suggest that planets one to four times the size of Earth may be abundant in the galaxy. The number of Earth-size and super Earth-size candidates has increased by more than 200 and 140 percent since February, respectively.

There are 48 planet candidates in their star’s habitable zone. While this is a decrease from the 54 reported in February, the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalogue, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.

“The tremendous growth in the number of Earth-size candidates tells us that we’re honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable,” said Natalie Batalha, Kepler deputy science team lead at San Jose State University in California. “The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods.”

Image credit: NASA/Ames/JPL-Caltech