High coupling phononic SH-SAW resonators for in-liquid operation

In this communication we report on initial studies on the in-liquid operation of surface acoustic wave (SAW) phononic resonators employing shear (SH)-SAWs. The mode of operation is a SH-SAW with very high electromechanical coupling, propagating in the X-direction of Y-cut LiNbO3 substrates. Measurements of the resonators immersed in ethylene glycol - water mixtures are presented along with an analysis of the underlying phenomena that determine device sensitivity. We found that the change of electromechanical coupling due to variations in the dielectric permittivity of the liquid becomes a leading contributing factor to device sensitivity. The results of this study are expected to enable the design of a novel class of phononic bio-sensors for lab-on-a-chip applications.