A Micro-Electromechanical System Based Hydrogen Gas Sensor

Abstract

We describe the fabrication processes and the characterizations of a MEMS (Micro-electromechanical systems) based hydrogen gas sensor. The gas sensor is made by MEMS based on a semiconductor fabrication method except for the ceramic bulk. The heating electrode and sensing electrode were formed being apart from the substrate by using MEMS and SnO2 ceramic bulk as a gas sensitive material was formed extending over the heating and sensing electrode. The SnO2 gas sensor with the micro-hotplate showed good response to the H-2 gas at 50 similar to 20,000 ppm and high selectivity as compared to other gases as CO, H2S, and CH4. The value obtained of the TCR is 1.61 x 10(-3) K-1. The TCR of the micro hotplate is lower than the TCR of bulk Pt as the thickness of the micro hotplate is only 2 mu m.