Harsh Environment Water Vapour Sensing Platforms in SOI Technology

Although commercial harsh environment sensors have been developed to operate above 200 °C, such as in industrial process control, automotive, or aerospace, they are still limited in types, technologies, or reliability issues. Our motivation is to develop a low cost, low power and reliable sensor with integrated electronics interface for applications above 200 °C [1-2]. In this paper, we are reporting the performances of a micro-machined gas sensor designed to monitor the water vapour concentration above a methane burner up to 225 °C. The sensor is a Silicon-on-Insulator (SOI) micro-hotplate [3] with an Al2O3 passivated impedimetric transducer. The sensor is hybrid integrated with a SOI readout interface to convert the measured impedance to frequency. Most comparable sensors have a high temperature unstable polysilicon as a heater material and bulk CMOS technology, reliable at maximum 150 °C [4-5]