Quartz-Crystal Microbalance Gas Sensors Based on TiO 2 Nanoparticles

Quartz-crystal microbalance (QCM) sensors obtained by a facile deposition of TiO 2 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 NO 2 , 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 NO 2 , and only a fairly low response to CO. Both CO and NO 2 responses depend strongly on the relative humidity (RH). So, NO 2 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.