By marrying a sensitive detector able to distinguish hundreds of different chemical compounds with a pattern-recognition module that mimics the way animals recognize odors, National Institute of Standards and Technology (NIST) researchers have created a new approach for "electronic noses." The detector could be a potent tool for sniffing out nerve agents, environmental contaminants, and trace indicators of disease, in addition to monitoring industrial processes and aiding space exploration.

The technology is based on interactions between chemical species and semiconducting sensing materials on top of MEMS microheater platforms developed at NIST. The electronic nose comprises eight types of sensors in the form of oxide films deposited on the surfaces of 16 microheaters, with two copies of each material. Precise control of the individual heating elements allows the scientists to treat each of them as a collection of virtual sensors at 350 temperature increments between 150 to 500 degrees C.

The great advantage of this system, according to NIST researchers Barani Raman and Steve Semancik, is that one doesn't need to expose the array to every chemical it could come in contact with to recognize and/or classify them. Breaking the identification process down into simple, discrete steps using the most information-rich data also avoids 'noisy' portions of the sensor response, thereby minimizing the effects of sensor drift or aging.

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