Newswise — Researchers at the University of Missouri-Rolla and Motorola Inc.'s Advanced Technology Center in Schaumburg, Ill., are developing three-dimensional switches and tiny fuel cells to improve the reception quality and extend the operating time for wireless communications and other wireless sensing devices. "We are trying to make better switches, called Meso-MEMS, for wireless technology," says Dr. Matthew O'Keefe, associate professor of metallurgical engineering and one of the leaders of this research project. The use of Meso-MEMS (MEMS stands for micro-electro-mechanical systems) as switches will not only improve reception quality, but will save energy. O'Keefe and Dr. James Drewniak, professor of electrical and computer engineering at UMR, are working with Dr. Keryn Lian of Motorola Labs. "The basic switch technology gives you lower electrical loss and a higher quality signal," says O'Keefe. The switch would enable a cell phone, for example, to be used in any geographic location by simply changing its frequency operation band. Recent tests have shown this approach is an improvement over current technology. "This system will actually enhance the consumer's cell phone performance by providing a cleaner, stronger signal with less static," says O'Keefe. Over the course of four years the Defense Advanced Research Project Agency (DARPA) and the Department of Defense (DOD) have contributed $2.6 million toward the research. O'Keefe, Drewniak and their students have worked directly with Motorola's Advanced Technology Center and the Air Force Research Laboratory at Wright Patterson Air Force Base in Dayton, Ohio, to develop small radio frequency (RF) switches. These switches will be used in future commercial and military products. "These will be a better alternative to what is being used now," says O'Keefe. These meso-MEMS switches work much like a light switch. A meso-MEMS switch is either on or off, unlike the current solid state technology, which is on at some level all the time. One significant advantage to using this switch is that, because it does turn completely off, it saves energy. Energy savings are also realized with current MEMS switches made of silicon, but silicon RF MEMS switches are relatively expensive, O'Keefe says. The Motorola/UMR team has discovered that alternative polymer and metal materials work just as well as silicon, and for a much lower price. In the next phase of the program the researchers will also be developing tiny fuel cells to power these wireless devices. The fuel cells would provide power for these products longer than traditional batteries in such wireless devices as cell phone. "The military could conceivably put a sensor out in the desert and leave and it would be capable of sending information for an extended period of time," says O'Keefe. Unlike batteries, however, they do not run down or require electrical recharging. Fuel cells consist of two electrodes sandwiched around an electrolyte, or membrane. Oxygen passes over one electrode and hydrogen or some other fuel source over the other, generating electricity, water and heat. "In addition to the successes in joint technology development, the UMR/Motorola team has established a great partnership to bridge today's industry and academia through knowledge sharing and graduate student internships," says O'Keefe. Over the past three years, four UMR graduate students have spent their summer working at Motorola. These students have not only contributed to the Motorola research, but also gained valuable industrial experience, says O'Keefe. Other UMR researchers involved in this effort include Dr. Steve Pekarek, associate professor of electrical and computer engineering; Dr. Fatih Dogan, professor of ceramic engineering; and Dr. Brad Miller, assistant professor of mechanical and aerospace engineering and engineering mechanics.
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