Chemoresistive metal oxide gas sensor: working principles and applications

The aim of this paper is to explain to young students why chemoresistive metal oxide semiconductors (MOS) gas sensors are important and widely employed in many applications. The paper deals with the fundamentals principles of these devices and their continuous improvement, due to high level of compatibility with microelectronics technology and the employment of nanostructured materials as sensing interfaces. The main operating conditions and mechanisms are also described, in order to better understand the guidelines followed to improve these devices in terms of sensing performances (sensitivity, selectivity, fast response/recovery time, repeatability, and reliability) finalized to their practical applicability. Finally, we suggest a possible brief activity on how to explore gas sensor employment and operating features in a classroom.