Temperature and Humidity Effects on SAW Hydrogen Sensor and Compensation Method

Palladium-nickel (Pd/Ni) thin-film-coated surface acoustic wave (SAW) sensor exhibits excellent performance for sensing hydrogen (H2), but it still suffers from the response drift induced by environment temperature/humidity in practical applications. To enhance the stability and accuracy of SAW sensors, this work demonstrates the effects of temperature and humidity on Pd/Ni alloy thin-film-coated SAW sensors and proposes a temperature/humidity compensation method. Pd/Ni-loaded SAW sensor integrated microheater is fabricated on Y35°X quartz crystals by a photolithographic technique and a magnetron sputtering method, and the hydrogen-sensing experiments are conducted at different temperatures (−25 °C to 55 °C) and humidity (0%–60%). The results indicate that the baseline and response sensitivity of the sensor are significantly affected by temperature. The interference of humidity is relatively small due to the microheater, which reduces the adsorption of water molecules on the Pd/Ni film. Further analysis shows that the effect of temperature on the system components is cross-coupled, so an in situ temperature/humidity compensation method is proposed from the perspective of the system as a whole. By applying this compensation method, the baseline drift induced by temperature/humidity of the system is reduced by 97.86%, and the concentration prediction error is reduced from 22.58% to 4.83%. This demonstrates the effectiveness of the compensation method and provides technical support for the reliable application of SAW sensors in complex environments.