Modeling and simulation of fluid SAW-sensors under acoustic plate mode operation

This paper presents the use of Surface Acoustic Wave (SAW)-sensors in the c haracterization technique for fluid determination. A SAW-sensor model is an alyzed with LiNbO3 substrate using the acoustoelectric effects of the loadi ng fluid on the propagating wave. The changes of the relative velocity and the attenuation of the acoustic wave caused by these effects are used as a characterization criterion for the loading fluid material. In the analysis of this SAW-sensor model, the thickness of the fluid layer is assumed to be infinitely thin but finite. The thickness of the separating air gap betwee n the fluid and the substrate is very small relative to the wavelength. On the other hand, the substrate has a finite thickness. Since operation under acoustic plate mode is assumed, the sensing wave may reflect from the top and the bottom surfaces of the substrate. Computer programs are developed t o simulate different fluid behaviors and different types of piezoelectric m aterials. The simulated obtained results indicate that SAW-sensor can be us ed as a simple and easy technique to determine the properties of different fluids. They are compared with the published experimental results. Moreover , this sensor can be employed for chemical sensors, biosensors, and polluti on applications.