A New Pellistor-Like Gas Sensor Based on Micromachined CMOS Transistor

A new generation of thermal sensors based on a suspended thermal transistor MOS (TMOS), fabricated in the standard CMOS-SOI process, released by postetching, has been recently developed. One of the important features of TMOS is its high responsivity due to the transistor built-in amplification and subthreshold operation enabling a wide range of battery applications. This paper focuses on a new gas sensor, dubbed GMOS, based on the TMOS. The GMOS is a catalytic gas sensor (pellistor-like), and as such detects combustible gases in air. The CMOS-SOI technology combined with tungsten metallization enables operation at very high temperatures (450°C was tested). The sensors and readout are processed with the same CMOS-SOI technology. Accordingly, the GMOS sensor, processed in low-cost CMOS-SOI technology, promises to become the widely accepted gas sensing approach for mobile applications, including wearables, smart homes, as well as smartphones.