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, an d selectivity. To address these problems, we have designed and fabrica ted collective analog VLSI circuitry that processes the outputs of an array of chemical sensors in a manner that allows robust chemical disc rimination. In testing, this circuitry chooses the winner (the maximum output) and the loser (the minimum output) in an array of tin oxide s ensors that are differentiated by temperature. The locations of the wi nner and loser and their relationships with neighboring sensors have p roven sufficient to discriminate among several types of alcohol and sm oke. We present this approach to chemical discrimination as a fast, in expensive alternative to more traditional methods of chemical sensing.