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The present paper presents a hardware simulator of an integrated array of microminiaturized SnO2 sensors and their preconditioning circuit for measurement of CO, NOx and VOC (Volatile Organic Compounds) pollutants emitted in urban traffic. The SnO2 sensor array is simulated by three discrete SnO2 sensors together with their conditioning circuitry and the power supply coupled to a microcontroller. SnO2 sensors are characterized by short response times and high fiability, but low discrimination. The design main goal is to surpass this problem through technological design of the sensors, electrical circuit optimization and special software for the measured data. The hardware simulator includes three low power sensors, obtained on SnO2 deposited on ceramic, analogue with the sensors which will be integrated in the array. Experimental calibration curves were obtained, using a special calibration chamber for each of above gases. The calibration and measured data are included in a special designed software, using Visual Basic 6.0 and a subroutine of Fortran Power Station Library. The hardware simulator presented in this paper was used to measure the concentrations of the pollutants emitted from the Bucharest urban traffic, and are in good agreement with those reported by the Romanian National Agency for Environmental Protection.
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