Quartz-Crystal Microbalance Gas Sensors Based on TiO2 Nanoparticles

Quartz-crystal microbalance (QCM) sensors obtained by a facile deposition of TiO2 nanoparticles have been manufactured and tested. Their gas sensing performance is discussed from a theoretical point of view and then verified by means of ad hoc measurement systems, through experiments with two toxic gases, CO and NO2, and water vapor. The influence of UV irradiation on the sensor response has also been studied. Results show stable and repeatable responses, characterized by a very high sensitivity to water vapor, a good sensitivity to NO2, and only a fairly low response to CO. Both CO and NO2 responses depend strongly on the relative humidity (RH). So, NO2 sensing should be performed in a controlled humidity environment. Devices proved to be reliable detectors of low RH values. Advantages as low cost, facile preparation, RT operation, good stability, and high/moderate sensitivity, make these devices attractive as an alternative to mostly used gas sensors.