Development of an antenna coil type sensor device for hydrogen leakage detection

An antenna coil type hydrogen gas sensor device was fabricated and evaluated for applying to radio frequency identification (RFID) tag which can easily realize highly reliable and multipoint hydrogen leakage detection system. An antenna coil composed of platinum thin film was formed by photolithography onto a quartz-glass substrate. Then, a platinum-supported tungsten trioxide thin film was deposited on that coil by spin coating method. A frequency dependence of electrical properties (S-parameters) of the sensor device in air and in 4 vol.% hydrogen balanced with nitrogen gas was investigated in the range from 300 kHz to 3 GHz. The considerably change in frequency dependence of S11 with the exposure to hydrogen gas was observed. The result indicated high sensitivity of this sensor device and the possibility of wireless transmission of the information about hydrogen leakage. The 90% response time was about 3 s at 188 MHz. The sensitivity to hydrogen in air was lower than that in nitrogen atmosphere. It could result from the competitive oxidation reaction of tungsten bronze by oxygen. However, the sensor device was able to detect hydrogen gas in concentration range below lower explosion limit. In addition, the change in S21 between the sensor device and a conventional antenna coil was also demonstrated.