Acoustic wave devices for sensing in liquids

Horizontally polarized shear waves (HPSWs) have been used for acoustic sensing of liquid viscosity and for measuring sub-monolayer mass changes accompanying electrode reactions. HPSWs are excited on a piezoelectric substrate using interdigital transducers in much the same fashion as the Rayleigh waves used in surface acoustic wave (SAW) sensors. HPSW sensors are shown to have several advantages compared to SAW devices and bulk crystal oscillators for liquid sensing.