Silicon-carbide-based MEMS for gas detection applications

Gas sensors are devices that can detect and/or discriminate gases in their surroundings. Some of these devices are based on vibrating structure covered with a coating sensitive to the species to detect. But such a layer can cause device failures issues like ageing, low reliability and high response time. Nonetheless, gas sensors are of importance for industrial environments in many applications. In addition, in some cases, the sensors must operate in harsh environments, that can lead to a severe degradation of the devices. In this paper, we propose to review different MEMS devices, without any sensitive layer, for gas detection applications. The objective is to measure a physical property of the gas in order to determine its concentration. With the microsystem devices, limits of detection as low as 0.2 % has been obtained, illustrating the capabilities of the structures elaborated. And in our case, due to the absence of sensitive film that must be adapted according to the species to detect, it leads to generic sensors, compatible with many different gases. Moreover, by combining the measures of 2 physical parameters, the discrimination of the gases, with their respective concentrations, is accessible.