ODOR DISCRIMINATION USING STEADY-STATE AND TRANSIENT CHARACTERISTICS OF TIN-OXIDE SENSORS

The development of useful chemical microsystems must include the selec tion of sensors and signal processing sufficient to solve chemical-sen sing problems in an accurate and robust manner. Unfortunately, many mi croelectronic chemical sensors suffer from drift, mismatch, and reprod ucibility problems that limit their performance in such microsystems. Appropriate signal processing, however, can overcome these limitations . Here, a chemical sensor array architecture and signal-processing fra mework are presented to discriminate between reducing chemicals in an array of tin-oxide sensors. The array consists of tin-oxide sensors op erating at various temperatures, and the resulting steady-state and tr ansient behaviors of these sensors are analyzed and thresholded into a binary output. This binary representation of an odor is constant over sensor drift and concentration changes, while remaining sufficient to discriminate between a variety of reducing chemicals (acetone, ethano l, hexane, isopropanol, methanol, and carbon monoxide) as well as mixt ures containing two of these chemicals.