SAW-Based Hydrogen Sensing: Mechanisms, Design Strategies, and Future Prospects.

Hydrogen is widely considered a clean and sustainable energy carrier due to its high energy density, abundant reserves, and zero carbon emissions during use. To ensure safety in hydrogen production, transportation, and utilization, the development of high-performance hydrogen sensors is of great importance. Among various sensing technologies, surface acoustic wave (SAW) sensors have attracted considerable attention due to their unique advantages, including rapid response and high sensitivity, which originate from the excitation and reception of acoustic waves by interdigital transducers and the strong surface disturbance sensitivity of piezoelectric substrates. This paper systematically discusses the sensing mechanisms of SAW hydrogen sensors, analyzes the effects of piezoelectric substrates and hydrogen-sensitive materials on sensing performance, reviews recent progress in hydrogen-sensitive films, and explores optimization strategies in electrode structure design and signal processing. Finally, the main challenges are summarized, and future development directions are outlined, aiming to provide theoretical support for the design and application of high-performance SAW hydrogen sensors.