Quartz crystal microbalance sensors based on TiO2 nanoparticles for gas sensing

In this paper the feasibility of Quartz Crystal Microbalance (QCM) sensors obtained by a facile deposition of TiO2 nanoparticles is presented. The gas sensing performance of these devices are studied by means of an 'ad hoc' measurement system, through experiments with two toxic gases, CO and NO2, and with water vapor. The effect of UV irradiation on the sensor response is also studied. The sensors provide stable and repeatable measurements, a very large response to water vapor, a good sensitivity to NO2, whereas the response to CO is small. Both the response to CO an NO2 are highly dependent on the relative humidity (RH). Moreover the experimental results show that the response can't in general be explained by simple adsorption-desorption reactions. The developed device can be used as humidity sensor, especially suitable for a reliable detection of low RH values. The application to NO2 detection needs a controlled humidity environment.