ZnO nanoneedles grown on chip for selective NO2 detection indoors

A conductometric sensor based on ZnO nanoneedles for the detection of NO2 is described. The material is grown on chip over Pt interdigitated electrodes patterned on alumina substrates without the need of a catalyst layer. The nanostructure growth relies on two different mechanisms (Vapor-Solid and Liquid-Solid) so nanoneedles with few μm of length and wurtzite structure are obtained. The procedure is optimized on chip, which supposes a significant advantage in the fabrication of nanostructures on sensing devices. The sensor response has been measured under a target gas (NO2) and two interfering pollutants (benzene and formaldehyde). Lower working temperatures than other pure ZnO nanostructures found in the literature have been achieved and limit of detection (LOD) in the order of ppb has been reached. The significant higher response to NO2 with respect to benzene and formaldehyde makes this sensing device suitable for selective NO2 detection indoors.