Design and fabrication of micro hydrogen gas sensors using palladium thin film

A highly sensitive hydrogen gas sensor of the multi-layer, micro heater type was designed and fabricated using a microelectromechanical system (MEMS) process. A sensing layer (Pd thin film) was fabricated by radio frequency (R.F.) magnetron sputtering. The electrothermal properties of the designed H2 sensor were analyzed by the finite elements method (FEM). When the heater voltage was 3.0, 3.5 and 4.0, the simulation data were 98.56, 124.46 and 154.34 °C and the measured data were 101.28, 124.20 and 149.42 °C, respectively. In both data, the operating temperature of the micro heater was positively correlated with the heater voltage. The results of sensitivity and response time after application of the heater voltage demonstrated an optimal heater voltage for this sensor of 4.0 V. The H2 sensor provided sensitivity (Rs) of 0.267% for 500 ppm – hydrogen gas at a heater voltage of 4.0 V. The gas sensitivity was positively correlated with the hydrogen concentration.