Investigation of Water Effects on Surface Acoustic Wave Transmission

Abstract Corrosion is a typical damage type in metallic structures. Free water on metallic structures can gradually lead to corrosion damage. In this study, we investigated free water sensing based on surface acoustic waves (SAWs). The fabricated SAW device consists of two interdigital transducers (IDTs) in a pitch-catch configuration on a lithium niobate (LiNbO3) piezoelectric substrate. Finite element simulations of SAWs generated by IDTs and SAW-droplet interaction were performed. To unveil the effects of a water droplet on SAWs and understand the mechanism of our SAW device, we simulated multiple cases with different volumes of water droplets. The simulation results show that the transmission amplitude gradually decreases with the water volume increase. A proof-of-concept experiment was performed by using a fabricated SAW device to detect a water droplet on the substrate surface. The experimental results show a similar trend as that of the finite element simulations.