An unconventional type of measurement with chemoresistive gas sensors exploiting a versatile measurement system

To characterize chemoresistive sensors based on novel materials a versatile measurement system is required that is able to accurately control/measure all the quantities of interest (among which test gas mixture composition, relative humidity, sensor surface temperature, sensor resistance). In the last years the authors have developed a laboratory measurement system with these characteristics [1], which can be used with chemoresistive sensors provided with both a heater and a temperature sensor. In this contribution an unconventional measurement technique made it possible by the above system, improved to be used also with sensors not provided with a dedicated temperature sensor, will be presented. The technique consists in driving the heater, on the basis of the sensing film temperature, in order to maintain constant the sensing film resistance while varying the test gas mixture composition.