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Apparently ceramics innovations can keep you on your toes - and keep track of your fingers. Florida-based Sonavation Inc. recently announced what they claim to be “the biometrics industry’s thinnest, most durable and highly accurate fingerprint sensor for the wireless and smartcard markets.”

The sensor, dubbed the SonicSlide STS3000 (not to be confused with the infamous MST3000) is based on a ceramic MEMS piezoelectric transducer array. According to Sonavation, the 3 mm array is formed by pillars, “each one-tenth the thickness of a human hair. The pillars have a unique set of properties that enable them to mechanically oscillate when an electric field is applied. The oscillations then register in 256 shades of gray to form the images of ridges and valleys of the fingerprint.”

The entire set of components has been reduced to a single unit 35 mm in length by 14.5 mm wide with a thickness of only 0.25 mm

The company says that a big advantage of their system is that since it’s not a semiconductor, there are no problems associated with electrostatic discharge that have reportedly impaired the use of semiconductor-based sensors in personal electronics such as laptops and mobile phones.

According to its manufacturer, the STS3000 is capable of withstanding more than 10 million swipes and uses less power than comparable system, and uses an ultrasound system that supposedly provides greater accuracy of fingerprint images than available through DC or RF capacitive silicon sensors

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In light of the previous post on the creation of platinum nanowires (as a low-cost fuel cell catalyst) via electrospinning, we stitched together an animation and several demonstrations of electrospinning tiny and nanoscale fibers.

The Flash animation comes to us via Patricia Heiden of Michigan Tech University. The videos come from Michael Boyer at Drexel University, Spinrati (The Electrospinning Gateway) and the IonSource and its video channel on YouTube.

Please note that most of these clips have no audio.

[flashvideo filename=wp-content/video/electrospinning.flv image=wp-content/video/video-static-test.jpg /]

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Platinum nanowire net with (left) and without problematic "beads." Credit: Univ. of Rochester

One of the big divides the world of proton exchange fuel cell research is between those who are looking for an alternative to platinum (such as the University of Dayton’s Liming Dai) and those who are sticking with a platinum catalyst.

The pro-platinum group, populated by realists, are quick to acknowledge that ordinary catalyst systems are prohibitively expensive because the cost of the precious metal makes fuel cells containing them unaffordable except for military uses, space applications and specialized research centers. For them, the trick now is to find a way to use the least amount of platinum possible without reducing a fuel cell’s power output. Not surprisingly, they think the platinum Holy Grail can be found in nanotechnology.

Along these lines, one research team from the University of Rochester thinks they may have found the solution: long platinum nanowires.

According to a paper in Nano Letters, the concept is to use wires only 10 nanometers wide but several centimeters long to create a catalytic web of platinum. Lead author James C. M. Li, a professor of mechanical engineering at the university, and graduate student Jianglan Shui says they learned how to produce the long wires using electrospinning techniques.

The platinum nanowires produced by Li are roughly ten nanometers in diameter and also centimeters in length-long enough to create the first self-supporting “web” of pure platinum that can serve as an electrode in a fuel cell.

Much shorter nanowires have already been used in a variety of technologies, such as nanocomputers and nanoscale sensors. But the duo turned to a process known as electrospinning, a relatively old, noninvasive technique that uses an electrical charge to draw very fine (typically on the micro or nano scale) fibers from a liquid or molten material.

It’s easy to understand the attractiveness of electrospinning in this application. The technique is known for producing high surface-to-volume ratios, strong (approaching theoretical maximum strength) and defect-free structures. Li and Shui apparently are able to use this method to create platinum nanowires that are thousands of times longer than any previous such wires.

The electrospinning wasn’t without problems. Initial attempts at it left Li and Shui with platinum beads projecting the platinum nanowires. The beads block the surface of the wires, and if enough are present, large amounts of catalytic surface are effectively inaccessible. “With platinum being so costly, it’s quite important that none of it goes to waste when making a fuel cell,” says Li. “We studied five variables that affect bead formation and we finally got it – nanowires that are almost bead free.

Li and Shui say their approach avoids some of the pitfalls that other researchers have run into when using nanoscale amounts of platinum, such as the tendency of nanoparticles of the metal to merge through surface diffusion, and to become dislodged by oxidation of the support material.

Li says he understands why few have used his long-wire method. “The reason people have not come to nanowires before is that it’s very hard to make them. The parameters affecting the morphology of the wires are complex. And when they are not sufficiently long, they behave the same as nanoparticles,” says Li.
Li and Shui are now working on methods to make the wires longer, more uniform and with even fewer beads. “After that, we’re going to make a fuel cell and demonstrate this technology,” says Li.

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Although there is a tendency to associate aerogel with more exotic applications, one of the frustrations has been finding ways to incorporate the temperamental material into common large-scale manufacturing and applications, such as insulation.

Some enterprises, however, are plugging away at the problems and are succeeding in making greater use of aerogel. One example is the teamwork between Birdair Inc., an Amherst, New York, based contractor that specializes in lightweight long-span roofing systems and tensile structures, Cabot Corp., a Boston based provider of specialty chemicals and high performance materials, and Geiger Engineers.

With the help of Geiger, Birdair developed an architectural fabric membrane that incorporates what the company calls Tensotherm, a composite made with Nanogel, an aerogel product manufactured by Cabot. Sandwiched between layers of Teflon, the membrane is less than a half-inch thick.

The beauty of a roofing system like this is that it is strong, extremely light weight and dampens sound. It also allows for what Birdair calls “daylight harvesting” – letting a large amount of diffuse sunlight to pass through.

Birdair is going to exhibit its roofing systems at the American Institute of Architects (AIA) National Convention and Design Exposition April 30–May 2 at The Moscone Center in San Francisco, CA.

Nanogel is actually Cabot’s trade name for a whole family of silica aerogels. Cabot says it has been producing Nanogel aerogel since 2003 at a plant in Frankfurt, Germany, and claims to be “the only company to develop a commercialized process that allows continuous production of the material under ambient conditions.” Cabot says it is able to manipulate the aerogel’s porosity, pore size and distribution, and bypasses normal drying methods. Beside architectural and building uses, Cabot is marketing its aerogel for use with oil and gas pipelines, coatings, cryogenic materials handling, outdoor apparel and personal care products.

Birdair, Geiger and Cabot announced their first roofing installation using the Tensotherm Nanogel last May at the Dedmon Athletic Center at Radford University in Radford, VA. Donald Geiger, founder of the engineering company, invented a roofing system that is low profile, cable-restrained and air-supported.

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The DOE promised to act fast in distributing its stimulus monies and it is. It’s been announced that one of the first offers is going to Solyndra, a Fremont, Calif., company with a maverick technology I profiled back in October. A $535 million guarantee will allow the company to obtain lower-than-market financing to expand its production of photovoltaic “panels” by opening a second production plant in California. “Fab 2,” as the new plant is called, is expected to have an annual manufacturing capacity of 500 megawatts per year.

As for the economic stimulus part of the deal, Solyndra says in a press release that, “[C]onstruction of this complex will employ approximately 3,000 people, the operation of the facility will create over 1,000 jobs, and hundreds of additional jobs will be created for the installation of Solyndra PV systems, in the U.S.” Actually, Solyndra’s units are markedly different than other PV units, with a tubular shape that allows each cylinder to collect sunlight from any angle. A coating within the tubes contains the light-sensitive material. By painting a surrounding roof white, the cylinders are capable of capturing reflected sunlight from their “down” side. The tubes also are more tolerant than PV panels when it comes to installation arrangements. Flat panels must be precisely angled with devices that add cost and time, and they must be anchored by ballast or “rooftop penetration” to meet wind-loading requirements. In contrast, Solyndra’s solar tubes can be laid beside each other in straight lines across a roof with minimal rooftop anchoring.

The company says installation costs can be cut in half. Solyndra tubes are made from a less expensive thin-film of semiconductor material. This material - comprised of copper, indium, gallium and selenium - is deposited on a glass tube, which is nested inside another glass tube. The outer tube concentrates sunlight and protects the solar film on the inside tube. See this post for a video of Solyndra’s manufacturing techniques. Under the previous administration, the loan guarantee program got stuck in a horrendous bureaucracy that was so FUBARed that proposals had been sitting for years. New DOE Secretary Chu promised to cut the application approval process to months and cut the application, itself, to less than 50 pages. Chu deserves a nod to sticking to his promise, and so does the DOE for taking a risk with a firm leveraging nontraditional but proven PV technology (and I don’t mean to imply that there is anything wrong with providing loan guarantees to traditional PV panel makers, either).

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