Improvement of Measurement Accuracy in Environmental Monitoring System Based on Semiconductor Gas Sensor

Abstract

There has been growing interest in developing gas sensor systems for environmental applications. The network of a large number of sensors deployed in the field is expected to enable monitoring of local air pollution problems in detail. Toward the development of a gas sensor network, this paper addresses the issue of accuracy in measuring NO2 concentration using a semiconductor gas sensor. Firstly, a sensor cell with a temperature control system is developed. Many gas sensors show variation in their response characteristics with the change in the ambient temperature. The experimental results on the sensor calibration show that the error in the measured NO2 concentration can be effectively reduced by stabilizing the temperature of the gas sensor cell. Secondly, a method for recalibrating the sensor system is discussed. It is shown by the field experiments that the sensor system can be recalibrated by placing the gas sensor system with a reference instrument and readjusting the calibration parameters to minimize the error in the measured concentrations. The proposed recalibration procedure will help to simplify the operation of a number of gas sensors deployed in the sensor network.