Gas sensors are essential components for today’s society, as they contribute to the improvement of indoor and outdoor air quality by detecting harmful gases such as CO, CO₂, NO_x or H₂S, or uncomfortable humidity levels in buildings. Currently, gas sensors are based on metal-oxide semiconducting materials, in which the sensing mechanism is the change of electrical conductivity due to the surrounding gas. The gas

concentration is thus detected as a change in the material’s resistivity. The sensitivity is a very important aspect in metal oxide gas sensing, since most compounds display poor responses. Sensitivity can be increased either by changing the work function, or by maximizing the surface to volume ratio using very thin films and nanostructured materials.

The main goal of the project is to increase the sensitivity of CuO-based gas sensors by fabricating a composite with several different types of morphology of ZnO, TiO₂ and BaTiO₃ nanostructures: nanolayers, nanowires and nanoparticles synthesized by different methods. Furthermore, we will produce ZnO, TiO₂ and BaTiO₃-based humidity sensors aiming for sensitivity above the state-of-the-art by deposition of the above mentioned nanostructures on substrates for conductometric measurements.

The basis of the constructed gas sensor devices will be constituted by Si-based, CMOS-compatible microhotplates (µhps). These will be used bare for the humidity sensors, whereas for the gas sensors we will first coat them with a CuO layer using spray pyrolysis. ZnO, TiO₂ and BaTiO₃ nanostructures will be produced by four different methods: sol-gel (dip- or spin-coating), hydrothermal synthesis, magnetron (RF) sputtering and pulsed laser deposition (PLD).

The tasks on realization of the project will be distributed between collaborating partners; preparation and structural characterization of ZnO, TiO₂ and BaTiO₃ nanostructures will be conducted in Croatia, while assembling of the sensors and study of the sensing properties will be conducted in Austria.