Nanoantennas could make for more efficient solar panels

Scientists from Tel Aviv University are creating what could be much more efficient solar panels, utilizing metallic 'nanoantennas' instead of silicon semiconductors

Radio waves are a type of electromagnetic energy, and when they're picked up by traditional metallic antennas, the electrons that are generated can be converted into an electrical current. Given that optical waves are also a type of electromagnetic energy, a team of scientists from Tel Aviv University wondered if these could also be converted into electricity, via an antenna. It turns out that they can - if the antenna is very, very short. These "nanoantennas" could replace the silicon semiconductors in special solar panels, which could harvest more energy from a wider spectrum of sunlight than is currently possible.
The nanoantennas are constructed out of small amounts of aluminum and gold, and are each less than a micron in length - because light has such a short wavelength (as compared to radio waves), short antennas provide the optimal absorption. After being created, the nanoantennas were then exposed to light, to determine how well they could receive and transmit light energy. According to the initial tests, 95 percent of the wattage being absorbed by the antennas was passed along, with only 5 percent being wasted.
Not only are the nanoantennas efficient, but when their length is varied, the wavelength that they can absorb changes. Therefore, the researchers believe that one panel containing a variety of lengths of otherwise-identical nanoantennas could harvest energy from a much broader solar spectrum than is presently allowed by semiconductor technology.
To that end, the Tel Aviv team is now in the process of creating experimental plastic solar panels, nano-imprinted with varying lengths and shapes of nanoantennas. They are also looking into the electromagnetic-energy-to-electrical-current conversion process, with hopes of improving it.
Although silicon is not a particularly expensive material, the scientists believe that the superior efficiency of their panels could allow them to be smaller than present photovoltaic panels, and thus more cost-effective.
Similar research is also under way at the Idaho National Laboratory, where researchers have been developing plastic sheet solar panels stamped with nanoantennas.

Floating weed inspires high-tech waterproof coating

A plastic material inspired by the leaves of the aquatic weed Salvinia molesta may lead to a coating that makes ships more buoyant and hydrodynamic 
It may be an invasive weed that's fouling waterways in the U.S., Australia and other countries, but it turns out that Salvinia molesta has at least one good point - it's inspired a man-made coating that could help ships stay afloat. The upper surface of the floating plant's leaves are coated with tiny water-repellent hairs, each of which is topped with a bizarre eggbeater-like structure. These hairs trap a layer of air against the leaf, reducing friction and providing buoyancy, while the eggbeaters grab slightly at the surrounding water, providing stability. Scientists at Ohio State University have successfully replicated these hairs in plastic, creating a buoyant coating that is described as being like "a microscopic shag carpet."

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In laboratory tests, the man-made coating performed just like the Salvinia hairs. In both cases, water droplets couldn't penetrate between the hairs, but did cling to the uniquely-shaped tips - they even hung on when the surface was tilted by 90 degrees. The adhesive force of the coating was measured at 201 nanoNewtons (billionths of a Newton), while the natural hairs managed an almost identical 207 nanoNewtons. While these numbers are far below those attained by substances such as adhesive tape, they are similar to those of gecko feet - and geckos seem to have no problem climbing walls.
"I've studied the gecko feet, which are sticky, and the lotus leaf, which is slippery," said lead researcher Bharat Bhushan. "Salvinia combines aspects of both."

If commercialized, the Ohio State-developed material could conceivably be applied to the hulls of ships or submarines. It is believed that it could provide the vessels with more flotation, while helping them sit in the water with more stability and move through it more easily.

Device that harvests water from thin air wins the James Dyson Award

Edward Linacre has won the 2011 James Dyson Award for his Airdrop irrigation concept

Young Melbourne-based inventor Edward Linacre has won the 2011 James Dyson Award, making it the second year in a row where the prestigious prize has gone to an Aussie. Linacre stole this year's competition with his Airdrop irrigation concept that collects water from thin air. The Swinburne University of Technology design graduate was driven to transform an ancient cooling technique into a new sub-surface irrigation system, following the enduring Australian drought that saw high levels of farmer suicide along Australia's Murray- Darling Basin.

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The Airdrop irrigation concept is a low-tech design that uses the simple process of condensation to harvest water from the air. Utilizing a turbine intake system, air is channeled underground through a network of piping that quickly cools the air to soil temperature. This process creates an environment of 100-percent humidity, from which water is then harvested. The collected water is stored in an underground tank, ready to be pumped out via sub-surface drip irrigation hosing. The Airdrop design also features an LCD screen displaying water levels, pressure strength, solar battery life and system health.

"The one that I made in the backyard at mum's house was creating about a liter of water a day," Linacre told Gizmag. Although the backyard trial was successful on a small scale, Linacre did prove that it could be implemented on a large agricultural scale. "The low-tech solution is perfect for rural farmers," explained Linacre. "[It's] something they can install, something they can maintain ... taking water out of the air and irrigating their crops."
The James Dyson Award is an international competition that attracts designs and inventions from young creators all over the world. As the winner, Linacre will receive GBP10,000 (US$14,000), with a further GBP10,000 (US$14,000) going to Swinburne's Faculty of Design.
Edward described the Airdrop system to Gizmag at the Australian Design Awards, in a video that we shot earlier this year.

Plasma-filled bags could replace the Petri dish

Creating a plastic bag as a bio-container using electrically-charged plasma The humble Petri dish may soon be a thing of the past. A team of researchers in Germany have developed a new technique for treating plastic bags with plasmas to turn them into sealed, sterile containers suitable for microbiology work with much less chance of contamination than traditional containers. This holds the promise of not only decreasing the possibility of contamination in stem cell and live-cell therapy techniques, but also the potential for cultivating whole human organs for transplant surgery.
The Petri dish is one of those simple, elegant inventions that quietly changed the science world. Consisting of a shallow, straight-sided glass or plastic dish with a matching lipped cover to seal it, the Petri dish has been a staple of biology laboratories since its invention by the German bacteriologist Julius Petri in 1877.

Unlike previous bottles and jars, the Petri dish is easy to fill with various growth media and samples can be introduced or removed without difficulty. The glass dishes are easy to stack and store and simple to sterilize in an autoclave, while the plastic versions are cheap and disposable. This was fine in the days when most biology studies revolved around growing bacteria colonies and similar work, but the rise of stem cell research and the development of techniques using live cells in therapy means that a much higher level of sterility and protection against contamination is required than the Petri dish and other traditional containers can provide.
A possible solution comes from a team of scientists in led by Dr. Michael Thomas at the Fraunhofer Institute for Surface Engineering and Thin Films IST in Braunschwieig, Germany. They have developed a technique for turning plastic bags into sterile, relatively inexpensive bio-containers. This is done by filling the bags with a special gas mixture at atmospheric pressure, then hermetically sealing them. The gas is then subjected to a high-frequency RF electric field, which turns the gas into an electrically-charged plasma. This chemically alters the inner surface of the bag, so that human cells can adhere to it and reproduce. Since the bag remains sealed at all times, it remains sterile. Cells are introduced into the bag using a hypodermic needle and samples are removed the same way, greatly reducing the chances of contamination. Also, like traditional Petri dishes, the bags can be filled with suitable growth media beforehand. However, unlike Petri dishes, experimental gases can be introduced as well before sealing the bag. And, being simply plastic bags, they are disposable, which removes the cost of cleaning and re-sterilization.

Growing organs for transplant

For Dr Thomas and his team, this is only the beginning for the bag's potential. They hope eventually to design a bag with a three-dimensional structure, which would allow them to graduate from growing simple cell cultures to fabricating entire human organs from scratch. If this can be achieved, then the implications for transplant surgery are immense. Currently, attempts at creating cultivated organs has met with little success because of the difficulty of getting cells to adhere to the "scaffolding" that biologists create for them, but it is hoped that these plasma bags may resolve this problem.

Light barrier used to repel mosquitoes

Anopheles Gambiae mosquito

You're in the middle of a great chat with friends on a warm summer night, and then "ouch" a mosquito interrupts your conversation with a bite on your forearm. Experimental physicist Szabolcs Marka hopes to make this occurrence a thing of the past, but in this case it's not aerosol spray or roll-on-repellant keeping the bugs at bay, it's a wall of light.
Marka is working on a project that uses infrared light to form a barrier between humans and mosquitoes, as well as other common insects such as moths and wasps. The theory is that you can use light to form a wall that separates space. In a phenomenon not fully understood, the mosquitoes that are outside the wall seem blocked, as if by a semi-invisible fence.
"The mosquitoes are probably scared," Marka explained to Forbes. "They could go through the light barrier without getting hurt, but they don't. That's the beauty of it because you don't have to necessarily kill them. You just make them go away."
The technology is a simple one. A standard laser pointed in the direction of your choice to block the entryway to your home, or outdoor space. "Light is very easy to manipulate and shape to many geometrics with optics," says Marka.
Incidentally, laser-powered help might also be on the way for those who do want to put a dent in the mosquito population.
Szabolcs Marka was given US$100,000 in seed money for his idea in 2008, as well as a $1,000,000 donation from the Bill and Melinda Gates foundation through the Grand Challenges Exploration grant.
The science has far-reaching implications in mosquito-ridden areas where malaria is prevalent. In Uganda alone, malaria is responsible for approximately 20-percent of all childhood deaths.
While a prototype for the mosquito repellant is probably several years away Marka's team is studying the effects of different types of light, as well as the intensity, color, and shapes that can ward off not only mosquitoes, but moths, wasps, and even bed bugs.
Cost figures don't exist just yet, but one would have to assume that simple laser technology wouldn't be cost-prohibitive.