Technology Bulletin 322

Electronic nose Need more chemical detection technology? Check out the "electronic nose technology" developed by the California Institute of Technology. Unlike other chemical sensing technology, it's not hindered by variables such as humidity or temperature. It also works in a hand-held package. Other chemical sensing products are the size of desktop computers, according to Cal Tech. The new technology is based on a series of 32 sensors composed of conducting particles evenly dispersed in a polymer matrix. Each sensor is unique, producing a different change in resistance upon exposure to chemical vapors. As the pattern of resistance changes, it provides a distinct response signature for the sample measured. The change in resistance is transmitted to a processor for identifying the type, quantity, and quality of chemical based on the pattern change in the sensor array. This response results in a distinct electrical "fingerprint" that is used for characterizing the chemical. The broadly tuned array of sensors detects multiple chemicals and works in most any environment without special sample preparation, isolation conditions, or cleansing between tests. Potential applications include: detecting the freshness of foods and beverages; diagnosing chemical compounds in exhaled air, urine and body fluids; detection of automobile emissions; location of land mines; and the detection of chemical spills and leaks from pipelines and storage containers. Cal Tech has licensed the first product to emerge from this technology to Cyrano Sciences, Inc. Fax: (626) 744-1777. Machine helps engineers understand metal fatigue The high-cycle fatigue machine, (See Designer's Corner p. 83) developed by the Southwest Research Institute (San Antonio, TX), uses a scanning electron microscope to help engineers understand metal fatigue. "The driving force behind developing the machine is metal fatigue of turbines in aircraft engines," says Stephen J. Hudak Jr., an institute scientist in the mechanical and materials engineering division. It allows engineers to observe the high-frequency stress process and resulting fatigue using the scanning electron microscope. The machine is currently in use on a major program sponsored by the U.S. Air Force Research Laboratory at the Wright-Patterson Air Force Base outside of Dayton, Ohio. A national team comprised of the University of Dayton Research Institute, Purdue University, several US engine manufacturers, and Southwest Research Institute is developing an improved design methodology that alleviates high-cycle fatigue problems in jet engines. Hudak says that three concerns are being evaluated at Southwest Research Institute: foreign object damage, interaction between fatigue cycles of different magnitudes, and fretting fatigue, which typically occurs where the turbine blade attaches to the disk. Retired Institute Scientist and consultant David L. Davidson is the principle developer of the machine along with Staff Engineer Andrew Nagy, Engineering Technologist John Cambell, and consultant Thomas E. Owen. They hope to commercialize the machine, and already have one interested manufacturer. Fax: (210) 522-3547. E-mail: shudak @swri.org. Laser detects chemicals Scientists at the National Institute of Standards and Technology (NIST) developed a new "cavity ring-down spectroscopy" system that uses laser light pulses for detecting chemicals. The system consists of a tiny translucent cube, two adjacent prisms, a laser, and a detector. "The cavity is a solid cube of fused silica about the size of a dime with four smooth surfaces," says Linda Joy, of NIST. One of the surfaces is curved for focusing the circulating light as it travels around the path defined by the cube's four faces. A laser pulse tunnels into the cube and loops around the path, sustained entirely by internal reflection for a distance of more than a kilometer before its intensity degrades. "The time it takes the light to degrade, or ring down, determines the type of chemical present," says Joy. Potential applications include detection of nerve gas, explosives, chemical weapons, and industrial emissions. NIST is interested in licensing the technology. Contact Terry Lynch, Fax: (301) 869-2751. Remote vehicle diagnostics provide valuable information Remote vehicle diagnostic systems (RVDS) combine automotive, electronics, computing, and telecommunications technologies to provide many types of information that are useful to vehicle designers and consumers, according to a report from Frost and Sullivan, a market research and consulting firm. "Data on vehicle performance in use helps engineers design better vehicles," says Inge Matthey, an industry manager for Frost and Sullivan's automotive group. "Recording how drivers drive their cars and analyzing the data will help designers make adjustments to future vehicle models," she says. Remote diagnostic systems use fault codes from the vehicle's electronic control module to transmit maintenance and performance data to a central site for analysis by an expert. For consumers, remote diagnostics provide information about impending failures. RVDS also prompt the servicing of vehicles before failures occur. Additional types of information valuable to consumers include vehicle theft notification, routing and location assistance, and emergency services such as notification of airbag deployment. Fax: (210) 348-1003. Clock accurate for 20 million years The U.S. Department of Commerce placed into operation a new atomic clock that will neither gain nor lose a second for the next 20 million years. The new cesium clock is three times more accurate than the atomic clock it replaces. So, who cares about measuring time so accurately? Plenty of people, according to Michael E. Newman, a spokesperson for the project. "Accurate time is important to global positioning systems. If their time is off by a fraction of a second, it could mean a positioning error of several hundred feet. For NASA, an error of a fraction of a second can translate into calculations that are off by hundreds of miles," he says. The clock uses a fountain-like movement of atoms to obtain improved reckoning of time. Cesium gas is introduced into the clock's chamber. Six infrared laser beams are then directed at right angles to each other at the center of the chamber. The lasers push the cesium atoms together in a ball. In the process of creating the ball, the lasers slow down the movement of the atoms and cool them to near absolute zero. Two vertical lasers gently toss the ball up (the "fountain" action) and then all lasers are turned off. Gravity pulls the balls back down. The procedure is repeated many times while microwave energy in the cavity is tuned to different frequencies. Eventually, a microwave frequency is achieved that alters the states of most of the cesium atoms and maximizes their fluorescence. The resulting frequency is the natural resonance frequency for the cesium atom (the characteristic that defines a second) and, in turn, makes precision timekeeping possible. Fax: (303) 497-3772. Fiber optics makes solar energy viable The efficiency with which we harness the power of solar energy could improve by threefold, according to Jeff Muhs, a researcher at the Department of Energy's Oak Ridge National Laboratory, Engineering Technology Division. "Instead of inefficiently converting visible light found in sunlight into electricity only to convert a sizable portion back into interior light, it makes more sense to just collect and distribute the light directly," says Muhs. "By using the visible portion of the light spectrum, we can reduce the amount of electricity we consume for lighting commercial buildings." Interior lighting is the single largest use of electric power in commercial buildings, accounting for more than a third of all electricity commercially consumed in the United States. The system developed by Muhs uses roof-mounted, two-axis tracking concentrators that separate the visible and infrared portions of sunlight. Using large diameter optical fibers, it distributes visible light into the interior of buildings. (See Design News, 1-19-98, p. 77) Fax: (423) 576-0226. Driving cars with hydrogen peroxide Researchers at Purdue University (West Lafayette, IN) are developing a new type of environmentally friendly fuel cell that runs on chemical reactions between hydrogen peroxide and aluminum and generates about 20 times more electricity per pound than car batteries, claim the developers. "It has a huge amount of energy potential," says John Rusek, an assistant professor of aeronautics and astronautics at Purdue, who is working with students to develop the cell. The hydrogen peroxide serves two roles: it is a "catholyte," meaning it is both the electrolyte, a liquid that conducts electricity and allows the reaction to occur, and also the cathode, or the portion of the battery that attracts electrons. The aluminum serves as the cell's fuel and its anode; as it oxidizes, it gives up electrons. Waste products include water and recyclable chemical compounds. The experimental cells do not immediately provide a steady supply of electricity. It takes about two hours for the cells to reach their peak electrical output before producing a steady current flow. If perfected, such an electricity source could one day replace conventional batteries in many applications, including portable electronic equipment, Rusek says. A poster paper about the research was presented in November, 1999 during the Second International Hydrogen Peroxide Propulsion Conference at the University. Call: (765) 494-4782 or e-mail: [email protected]. Creativity report Professors Robert and Michele Root-Bernstein of Michigan State University say that "the creative impulse" occurs in the mind before logic or linguistics come into play. They also say that creativity manifests itself through emotions, intuitions, and images, then translates ideas into formal systems of communication after it is developed in pre-logical form. In their new book, Sparks of Genius, the Root-Bernsteins describe thirteen thinking tools for sparking creativity. Go to www.msu.edu or call Robert Root-Bernstein at (517) 355-6475, ext. 1263.