Highly Sensitive Ball Surface Acoustic Wave Hydrogen Sensor With Porous Pd-Alloy Film

In order to commonly use explosive H-2 gas as an energy source, fast, sensitive, and low-power consumption sensor is required. We developed a ball surface acoustic wave (SAW) sensor with porous Pd-Pt alloy film to realize such a sensor. The sensor with 20% Pt alloying film was useful for the suppression of a phase transition of Pd and the detection of ppm order concentration at 35 degrees C. The amplitude response was proportional to the square root of the concentration, which was demonstrated for the first time in the field of SAW sensor, resulting in the detection limit of 3.7 ppm at signal to noise ratio of 3. The response time decreased to 1/5, compared with those of pioneering H-2 sensors working at room temperature. From these results, it was shown that the fastest and most sensitive hydrogen sensor working at room temperature could be realized using the ball SAW sensor with porous Pd alloy film.