Gas microsensors based on surface modified metal oxide nanomaterials

2019 edition

Milena Tomic

Metal oxide (MOX) based gas sensors are solid-state devices, which are widely used in a number of applications from health and safety to energy efficiency and emission control. Previously, various MOX nanomaterials such as WO3, ZnO, SnO2, and Fe2O3 with different morphologies (e.g. nanowires, nanorods) were identified as a potential gas sensing material due to their large number of surface sites, which facilitate the surface reactions with the monitored gas. In this work, the gas sensing properties of MOXs have been enhanced even further by the functionalization (or surface modification) with noble metals (e.g., Au, Pt), another MOX (e.g., CeO2, Fe2O3) or organo-functional molecules (e.g., 3-aminopropyltriethoxysilane – APTES) to provide electronic sensitization via the formation of nanoscale heterojunctions. To this end, aerosol-assisted chemical vapor deposition (AACVD) method has been used for obtaining and functionalizing nanostructures. In comparison with traditional methods, AACVD is industrially attractive due to its simplicity, relatively low setup and running costs and its scalability. The synthesized non-modified and modified nanostructures have been integrated over the active area of the Si-based micromachined transducing platforms fabricated in the Clean Room at the IMB-CNM, CSIC. The integration of the gas sensitive materials and the micromachined devices has been achieved using shielding masks during material synthesis. These sensor devices have been validated towards relevant gases such as CO, H2, and volatile organic compounds (VOCs) with very promising results that will be shown at the conference.