A low-power low-cost MEMS-based gas sensing platform

Beyond conventional temperature, humidity, pressure and acceleration sensors, low-power gas sensing is of main interest in the “smart sensors” vision of the Internet-of-Things, enhancing interactions between the users and their environment. In this thesis, we will show the capabilities of a new micro-electromechanical system (MEMS) architecture towards low-power gas sensors, i.e. consuming less than 1 mW, while maintaining CMOS compatibility. Before achieving the system integration of a fast and highly selective MEMS sensor dedicated to hydrogen detection as demonstrator, we faced four main research development steps and their associated challenges. 1) A MEMS sensing platform based on both ionization and capacitive transduction has been designed. 2) A new generic surface micromachining post-process using polyimide as the sacrificial and anchoring layer, as well as the template for nanowires synthesis, has been investigated. 3) Looking forward the chemical analysis of gaseous compounds by fingerprinting their field ionization characteristics, a MEMS field ionization sensor has been modeled and fabricated as proof of concept. 4) Finally, palladium functionalization of the MEMS platform has been achieved for selective hydrogen sensing, based on the actuation of double-clamped aluminum beams by a palladium/aluminum bimorph on a quarter of their length. New steps have been taken in heterogeneous system integration. The way is open towards fast, selective, low-cost and low-power sensing applications, two orders of magnitude less consuming than current gas sensors based on solid-state resistive materials.(FSA - Sciences de l'ingénieur) -- UCL, 201