Micromechanical fabrication of low-power thermoelectric hydrogen sensor

To detect gaseous hydrogen is of critical importance to acceptance and utilization of hydrogen as an energy carrier. Micro-machined sensors are a new generation of sensor technology combining existing integrated circuit fabrication technology with novel deposition and etching processing. This sensor structure provides a platform where the operating temperature can be rapidly changed to achieve desired response characteristics. We prepared the micro-thermoelectric hydrogen sensor (micro-THS) with the combination of the thermoelectric effect of SiGe thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation. We have focused on reducing the power consumption by modifying the micro-sensor design with micro-heater on a suspended thermal isolation structure. Hydrogen response properties of the micro-THS were also investigated. The power consumption of the micro-THS was greatly reduced by fabrication of the micro-heater on membranes. The effective area of the sensor was heated up on the micro-heater to 100 °C with the power consumption of 0.34 W. The response time, T90 of the micro-THS was faster than those of other type sensors such as semiconductor-type. The operating temperature at 100 °C detected hydrogen for the concentration from 0.01 to 3% in air, with a good linearity of voltage signal versus gas concentration. Pt catalyst only showed the high catalytic activity to hydrogen; hence, high hydrogen selectivity was achieved.