Detection and Discrimination of Formaldehyde with CuO/SnO2 dual layers MOS Gas Sensors Operated with a Pulsed Temperature Modulation

In this work, the authors present a new approach to detect and discriminate sub-ppm level of formaldehyde with metal oxide semiconductors (MOS) gas sensors based on nanostructured layers of SnO2, CuO, or a combination of the two. These sensitive layers are deposited on silicon micro-hotplates and operated with a pulsed temperature modulation between 100 and 500°C under 50% of relative humidity (%RH). This method allows a very specific sensor response to formaldehyde compared to other gases such as CO or NO2. This sensor set up (combination of sensitive layers and pulsed temperature mode) opens the way toward an efficient formaldehyde detection method for indoor air quality applications.