SIGNAL-PROCESSING FOR IMPROVING GAS SENSOR RESPONSE-TIME

In this paper, we describe a system for reducing the response time of gas sensor arrays. The system uses analog signal processing techniques to analyze the transient response of sensory inputs sufficiently to d iscriminate among chemicals of interest before steady state is reached . The signal processing thresholds the sensory inputs at periodic inte rvals during the transient response, thereby producing a binary wavefr ont that is stored and retained for discrimination tasks. Experimental results described in this paper effectively reduce the response time of an array of discrete tin-oxide gas sensors from 10 to 2 s; experime ntal data are consistent across a range of concentrations for a variet y of reducing gases. We expect that equivalent improvements in respons e time will also be possible for integrated microsensor systems using the same techniques described in this work. (C) 1997 Elsevier Science S.A.