You are browsing the archives of 2009 December.

Dan Arvizu, Director of the National Renewable Energy Lab, discusses the role of research and development in the age of renewable energy. Run time 1 hour.

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A video camera transmits images to a processor, which displays the images on an LCD screen on the inside of patient's goggles. The LCD display transmits infrared light pulses that project the image to photovoltaic cells implanted underneath the retina. The photovoltaic cells then convert light signals into electrical impulses that in turn stimulate retinal neurons above them. (Credit: Stanford University.)

Researchers at Stanford University recently announced that they have developed a new artificial retina implant that uses photovoltaic power and could help the blind see. The problem with previous implants was that there was no way send power to the chip in order to process light and data inside the eye. Now, miniature photovoltaic cells are being used to provide power to the chip as well as to transmit data through the eye to the brain. The new device has great promise to help people afflicted by the loss of photoreceptor cells by using the power of the sun.

The device is placed behind the retina and is essentially an array of mini solar devices. In addition, the system utilizes is an external video camera that captures images, a pocket PC to process the video feed and a bright near-infrared LCD display built into video goggles, which transmit infrared light pulses to the photovoltaic device in the eye. The light pulses then produce electricity in the device, which transmits data through the eye so the brain can process it into a hazy picture.

The implant is built to a width of 3-mm wide and 0.03-mm thick, and includes three layers of flexible photovoltaic cells mounted with silicon posts. This new system is capable of producing vision of 20/200, which is beyond what is considered legally blind, but the researchers reasonable expect to achieve 20/100, which would produce a picture clear enough that a person could recognize faces and read large print.

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Monolithic ceramics represent the dominant and best-established segment of the industry). Ceramic matrix composites and ceramic coatings will achieve the more rapid gains, primarily due to their enhanced strength and durability.

A recently released report by the Freedonia Group shows that advanced ceramics will continue to penetrate applications such as capacitors, cutting tools, orthopedic joint implants and membranes, where they are valued for their favorable performance characteristics. Demand is estimated to be lower for body armor, as the Obama administration’s goal is to significantly reduce military involvement in Iraq.

The use of advanced ceramics is highly dependent on the health of the electronic components and electrical equipment industries, which combined accounted for 43% of total demand in 2007. The U.S. electronic components industry is projected to remain sluggish, limiting further advanced ceramics demand.

The medical product market will post the most rapid gains, benefiting from the increasing utilization of ceramics in joint implants and dental procedures.

Other markets set to post above-average gains include chemicals and plastics, environmental, industrial machinery and transportation equipment.

In the environmental market, pollution control is the largest application, but interest in reducing the country’s dependence on foreign oil will also provide opportunities. Emerging applications include the use of ceramic bearings in wind turbines and ceramic materials in photovoltaic modules.

The full report can be viewed at ceramicindustry.com.

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3-D nanoscale structure of the inside of a synthetic calcite crystal grown in an agarose gel. In this environment, the crystal grows around the polymeric fibers. Credit: Estroff/Muller labs

Materials scientists continue to try to understand how biological systems are able to create superior crystalline materials such as the calcite found in sea shells, sea urchin spines and even algae. One group of these biomineralization investigators is led by Lara Estroff, a Cornell University assistant professor of materials science and engineering. She and her colleagues are studying how lab-created calcite crystals grow in tandem with proteins and other large molecules. They reported their findings in the Nov. 27 issue of the journal Science.

“We knew the organics were in there, but what no one had been able to do up until now was actually see what that organic-inorganic interface looked like,” said Estroff, whose lab focuses on the synthesis and characterization of bio-inspired materials.

Estroff and graduate student Hanying Li grew samples of calcite in a hydrogel called agarose. Li and Estroff already had determined that this gel environment made the crystals grow very differently than in solution. This time, the researchers prepared their crystals with Focused Ion Beam technology to slice samples thin enough for an electron beam to pass through for imaging.

Scanning transmission electron microscopy methods developed by associate professor of applied and engineering physics David Muller and physics graduate student Huolin Xin revealed that the crystals trap large molecules by growing around them.

Estroff says their research provides more ideas on how to make and manipulate nature-inspired composite materials. They say the applications could range from electronics to photovoltaics to completely new classes of materials.

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Representative thin crystalline-silicon photovoltaic cells – these are from 14 to 20 micrometers thick and 0.25 to 1 millimeter across. (Image by Murat Okandan)

Via press release, Sandia National Lab announced that scientists have developed microphotovoltaic cells that could revolutionize the way solar energy is collected and used.

The cells are fabricated using microelectronic and microelectromechanical systems (MEMS) techniques common to today’s electronic foundries. They are expected eventually to be less expensive and have greater efficiencies than current photovoltaic collectors that are pieced together with 6-inch- square solar wafers.

Benefits for microphotovoltaic cells include new applications, improved performance, potential for reduced costs and higher efficiencies.

Eventually units could be mass-produced and wrapped around unusual shapes for building-integrated solar, tents and maybe even clothing,” said Sandia lead investigator Greg Nielson. This would make it possible for hunters, hikers or military personnel in the field to recharge batteries for phones, cameras and other electronic devices as they walk or rest.

Other possible applications for the technology include satellites and remote sensing.

From 14 to 20 micrometers thick (a human hair is approximately 70 micrometers thick), microphotovoltacis are 10 times thinner than conventional 6-inch-by-6-inch brick-sized cells, yet perform at about the same efficiency. Because flexible substrates can be easily fabricated, high-efficiency PV for ubiquitous solar power becomes more feasible.

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