A MEMS-type Micro Sensor for Hydrogen Gas Detection

J.-H. Yoon, B.-J. Kim, J.-S. Kim
University of Seoul, KR

Keywords: MEMS, hydrogen sensor, palladium thin film

Summary:

In this study, a highly sensitive hydrogen gas sensor of the multi-layer and micro-heater type was designed and fabricated using a microelectromechanical system (MEMS) process. The dimension of fabricated hydrogen gas sensor was 5 mm×4 mm and sensing layer were deposited in the middle of the device. A platinum thin film was patterned for the sensing electrode and the micro heater. The electrothermal properties of the designed H2 sensor were analyzed by the finite elements method (FEM) method. The operating temperature of the micro heater was positively correlated with the heater. At hydrogen concentrations of 500, 1,000 and 2,000 ppm, the Rs of the H2 sensor was 0.271, 0.378 and 0.638 %, the response time was 35 seconds at 1,000 ppm, and the recovery time was 82 seconds. The hydrogen adsorption and desorption processes were clearly improved in comparison with those of other non-micro heater H2 sensors. The Rs (ratio of sensor resistances in air and after the hydrogen gas injection) of the H2 sensor at an applied heater voltage of 4.0. The sensor showed a very high sensitivity and good positive linearity with concentration. Also, the sensitivity of H2 gas was very dependent with the thickness and morphology of Pd-nanosized film. The gas sensitivity and response properties showed different behaviors when palladium film was deposited on the anodic aluminum oxide (AAO) layer.