A novel mixing surface acoustic wave device for liquid sensing applications

This paper presents a novel mixing surface acoustic wave (M-SAW) device using multiple Aluminum (Al) interdigital transducer (IDT) layers for liquid sensing applications. The stronger mechanical wave beam generated by the multiple input-IDT layers on the thin film (1 μm) Aluminum Nitride (AlN), consists of different-phase acoustic waves that can travel through a liquid medium. In contrast to the whole signal leaking into liquid medium as in typical SAW devices, the signal obtained at the receiver of the M-SAW device only has a decline in the Rayleigh component. The experimental results show that it is possible to interact with the liquid medium placed on the surface and extract information about the liquid volume based on the phase change. Phase shifts of -16.35°, -11.23°, -4.84°, and -0.86° are obtained for different volumes of demi-water after 10 seconds, 2, 4 and 5 minutes of vaporization, respectively.