Design and fabrication of a MEMS-based gas sensor containing WO₃ sensitive layer for detection of NO₂

Abstract

A gas sensor based on microelectromechanical systems (MEMS) technology containing a WO3 sensitive layer was designed, simulated, and fabricated. The gas sensor consists of a silicon substrate, a platinum microheater, gold interdigitated electrodes, and a WO3 sensitive layer. The active area with dimensions of 0.4 mm×0.4 mm is located at the center of a sensor (3 mm×3 mm). The experimental results show that the microheater provided heating for the WO3 sensitive layer at low power consumption and accurate temperature control. At a power consumption of only 40 mW, the temperature reached 319°C at the center of the MEMS platform with uniform heating. In addition to that, the above mentioned gas sensor exhibited a high response to NO2 with optimized sensitivity recorded at the working temperature of 170°C. With 10 ppb of NO2, the response of the sensor could reach up to 5.8 and the power consumption is 17.2 mW.