A review of MEMS-based metal oxide semiconductors gas sensor in Mainland China

With the growing demand for gas monitoring in various fields as the fast development of the internet of things, metal oxide semiconductors (MOSs) gas sensors based on the advanced microelectromechanical systems (MEMS) technology have achieved great developments in the past decades, especially in mainland China. This review summarizes the development of MEMS-based MOSs gas sensors in terms of the MEMS micro-hotplate, wafer-scale deposition and patterning methods for MOS materials, and several latest applications. Various designs of the micro-hotplates have been proposed, particularly, the suspended membrane type with low power consumption. By combining the 'bottom up' and the 'top down' strategies, MEMS provides a promising solution for wafer-scale fabrication process of MOSs based gas sensors, which have been successfully applied for the detection of ethanol, H2, H2S, toluene, HCHO, Freon etc. With the diversiform nano-structures of MOSs and emerging machine learning algorithm, great progress has been made recently on the aspects of the sensing performance, pulse heating and intelligent sensing systems.