Design and Fabrication of a MEMS-based Gas Sensor

In this study, the micro gas sensor for NO(x) gas was fabricated by using a MEMS technology and sol-gel process. The sensing electrode and micro heater were designed to be a co-planar typed structure in the Pt thin film layer. The fabricated micro platform had a low power consumption of 67 mW at 2.0 V of heater voltage and 300 degrees C of operating temperature. Indium oxide as a sensing material for NO(x) gas was synthesized by a sol-gel process with indium isopropoxide. The particle size of synthesized In(2)O(3) was identified as about 50 nm. The maximum gas sensitivity as relative resistance (R(s) = R(gas)/R(air)) occurred at 300 degrees C with the value of 8.0 at 1 ppm NO(2) gas. The present study shows that a MEMS-based gas sensor is a potential candidate for the automobile AQS (air quality system) gas sensor with many advantages of small dimension, high sensitivity, short response time and low power consumption.