High sensitivity SAW hydrogen gas sensor based on thermal conductivity effect

Wide-range and high-sensitivity hydrogen sensors are critically important for hydrogen safety in aerospace and advanced transportation sectors. This work demonstrates a thermal-conductivity surface acoustic wave (SAW) based sensor to achieve high sensitivity hydrogen sensing. By integrating thermal balance and acoustic wave equations, a precise mechanistic model elucidating the structure-activity relationships among gas flow rate, operating temperature, and MEMS architecture in determining sensing sensitivity is constructed. Guided by this model, the SAW hydrogen sensor with on-chip microheater integration was developed. Furthermore, a highly integrated SAW hydrogen sensing system with ultra-low baseline noise (<30 µV) was constructed for performance evaluation. Leveraging the exceptional thermal sensitivity of the SAW device and system stability, the optimized sensor achieves wide detection range (up to 100% vol), low detection limit (~6 ppm), rapid response and recovery time (T90/T10: ~15 s), excellent repeatability (error<2.4%) at a relatively low operating temperature (120 °C). The prepared SAW sensor provides an effective solution for hydrogen leakage monitoring across unprecedented concentrations (ppm-100% vol), establishing a new paradigm for hydrogen safety applications.