Measurement of acoustic properties of liquid using SH- and R-mode surface acoustic wave

A new liquid sensor using multi-mode surface acoustic wave (SAW) delay lines is described. SAW having shear horizontal (SH) displacement and Rayleigh (R) mode SAW have been used for measuring the acoustic properties of liquid. A special feature of the sensor is that the SH-SAW and R-SAW delay line are constructed in one substrate. Each mode SAW delay line were constructed on one 36° YX LiNbO₃ substrate. The SH-SAW was excited in the X direction and the R-SAW was excited in the direction at 90° to X on the substrate. The measurements were performed for water/glycerol solution. The experimental results show that the attenuation of the SH- and R-SAW are proportional to the viscosity and the density of the loaded solution, respectively. These results indicate that the SH-SAW and R-SAW are very suitable for measuring the acoustic properties of liquid