Enhanced Hydrogen Gas Detection Using SAW Sensor Through Oxygen Pre-Treatment

Hydrogen gas sensing is crucial in a variety of applications, including power generation, fuel cells, automotive, metallurgic and manufacturing industries. Some of the requirements for a hydrogen sensor are reliability, robustness, stability, fast response and recovery times. Surface acoustic wave (SAW) technology can offer these characteristics, and others such as small size and weight, wireless operation capability including multiple sensor interrogation, mass production reproducibility and low cost. In this work, an improvement in room temperature H
₂
gas sensor response time and stability is reported through the use of O
₂
treatments. The exposure to O
₂
, after interaction with H
₂
, reconditions the Pt-Al
₂
O
₃
composite thin-film used both as the electrode and H
₂
sensing layer. As a result, the SAW sensor frequency response recovery is over five times larger during the initial 20 minutes when compared to the exposure to N
₂
inert gas. In addition, the O
₂
treatment allows the recovery of the sensor to a state close to the one prior to the reduction by H
₂
within about an hour, thus leading to a stable device response, which is very difficult to achieve under the inert N
₂
environment even after tens of hours. The method is thus very promising in recovering the surface of sensing devices which rely on metallic composite electrodes and oxide films exposed to reducing environment.