SMART CHEMICAL SENSING ARRAYS USING TIN OXIDE SENSORS AND ANALOG WINNER-TAKE-ALL SIGNAL-PROCESSING

Traditionally, microelectronic chemical sensors have been plagued by a variety of performance problems related to drift, reproducibility, and selectivity. To address these problems, we have designed and fabricated collective analog VLSI circuitry that processes the outputs of an array of chemical sensors in a manner that allows robust chemical discrimination. In testing, this circuitry chooses the winner (the maximum output) and the loser (the minimum output) in an array of tin oxide sensors that are differentiated by temperature. The locations of the winner and loser and their relationships with neighboring sensors have proven sufficient to discriminate among several types of alcohol and smoke. We present this approach to chemical discrimination as a fast, inexpensive alternative to more traditional methods of chemical sensing.