A temperature-stable Pd nanofilm hydrogen sensor with a Wheatstone bridge structure

The performances of most hydrogen sensors are influenced by temperature. To reduce the influences of ambient temperature on the output response, a Pd nanofilm hydrogen sensor with a Wheatstone bridge structure was designed and fabricated by micro-electro-mechanical system (MEMS) technology. The voltage was used as the output response signal for data gathering. The performance of the Pd nanofilm sensor with a Wheatstone bridge structure was investigated. The Pd nanofilm hydrogen sensor exhibited a stable output response to hydrogen in the low concentration range within the test temperature range of 30 to 50 °C. The sensor consists of four palladium resistors, two of which have their surfaces covered by SiN x , so that they can compensate for changes in Pd resistance due to variations in ambient temperature, thus increasing the stability of the sensor. Delta U out of the sensor increased from 7.3 mV to 18.87 mV for hydrogen concentrations from 100 ppm to 800 ppm at 30 °C. The Pd nanofilm sensor exhibited high cycling stability in 8 cycles of measurement. In selective measurements of several reducing gases, the sensor responded to hydrogen only.