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July 10, 2009

Technology Roundup - Brainboosting EPO, Nanopillar solar power

1. Erythropoietin (EPO) cognitive performance in mice. .Erythropoietin improves operant conditioning and stability of cognitive performance in mice. Early erythropoietin treatment leads to lasting improvement of cognitive performance in healthy mice. This finding should be exploited in novel treatment strategies for brain diseases. The red blood cell boosting is used to treat anemia and some athletes use it to boost endurance.

2. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have demonstrated a way to fabricate efficient solar cells from low-cost and flexible materials. The new design grows optically active semiconductors in arrays of nanoscale pillars, each a single crystal, with dimensions measured in billionths of meter.

A flexible solar cell is achieved by removing the aluminum substrate, substituting an indium bottom electrode, and embedding the 3-D array in clear plastic


A flexible solar cell is achieved by removing the aluminum substrate, substituting an indium bottom electrode, and embedding the 3-D array in clear plastic

The efficiency of the test device was measured at six percent, which while less than the 10 to 18 percent range of mass-produced commercial cells is higher than most photovoltaic devices based on nanostructured materials – even though the nontransparent copper-gold electrodes on top of the Javey group’s test device cut its efficiency by 50 percent. In future, top contact transparency can easily be improved.

“There are lots of ways to improve 3-D nanopillar photovoltaics for higher performance, and ways to simplify the fabrication process as well, but the method is already hugely promising as a way to lower the cost of efficient solar cells,” says Javey. “There’s the ability to grow single-crystalline structures directly on large aluminum sheets. And the 3-D configuration means the requirements for quality and purity of the input materials are less stringent and less costly. Nanopillar arrays are a new path to versatile solar modules.”




3. MIT researchers have developed light-detecting fibers that, when weaved into a web, act as a flexible camera. Fabric composed of these fibers could be joined to a computer that could provide information on a small display screen attached to a visor, providing the soldier greater awareness of his surroundings.The new fibers, less than a millimeter in diameter, are composed of layers of light-detecting materials nested one within another.

Those layers include two rings of a semiconductor material that are light sensitive, each ring only 100 billionths of a meter across. Four metal electrodes contact each of the rings, extending along the length of the fiber, for a total of eight. Each semiconductor ring with its attached electrodes is in turn encased in rings of a polymer insulator that separate it from its neighbor.

The team starts with a macroscopic cylinder, or preform, of these elements. That preform is placed into a special furnace that melts the components, carefully drawing them into miniscule fibers that retain the original orientation of the various layers. The process can produce many meters of fiber.

Fink's team demonstrated the power of their approach by placing an object - a smiley face - between a light source and a small swatch of fabric composed of the fibers that was in turn connected to an external amplifying electrical circuit and computer.

The individual fibers measure the intensity of the light illuminating them and convert it to an electrical signal. Importantly, they are also designed to differentiate between light at different wavelengths or colors. A mesh of fibers is then deployed to measure light intensity distribution at different wavelengths across a large area.

In the current work, the smiley face was illuminated with light at two separate wavelengths. This generated a distinct pattern on the fabric mesh that was then fed into a computer. From there, an algorithm described earlier by the Fink team in Nature Materials assimilates the data to create a black-and-white image of the object on a computer screen.





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