A novel approach to fabricate metal oxide nanowire-like networks based coplanar gas sensors array for enhanced selectivity

As inspired by a novel materials-sensor integration fabrication strategy, nanowire-like network (NWN) structured ZnO, Co3O4, In2O3 and SnO2 films are synthesized directly onto an alumina substrate by the screen printing combined with micro-injecting and calcination (SPMIC) to fabricate a flat-type coplanar gas sensor array based on these four sensors. The gas-sensing properties of the sensor array are investigated at different operating temperatures (150–350 °C), and the best selectivity is interestingly found among the four indoor pollution gases including toluene (C7H8), formaldehyde (HCHO), acetone (CH3COCH3) and ammonia (NH3) at 300 °C. This is also confirmed by the principal component analysis (PCA) result that the four gases can be discriminated and recognized by the sensor array. The enhancement in the selectivity is attributed to the combination of special nanostructures with large surface area and sensor array based on the four different metal oxides. Furthermore, the SPMIC method is demonstrated to be an effective route not only to synthesize NWN structured metal oxides directly onto an alumina substrate without being destroyed, but also to fabricate coplanar sensor array based on various NWN structured metal oxide films.