Liquid Density Sensing Using Resonant Flexural Plate Wave Device with Sol-Gel PZT Thin Films

TL;DR

This study introduces a flexural plate wave resonator with sol-gel PZT thin films for liquid density sensing, demonstrating a linear relationship between resonant frequency and liquid density with promising experimental results.

Contribution

It presents a novel FPW resonator design using sol-gel PZT films, combining theoretical modeling and experimental validation for liquid density measurement.

Findings

Resonant frequency correlates linearly with liquid density.

The device effectively detects low viscosity liquids.

Sol-gel PZT films offer cost-effective high electromechanical coupling.

Abstract

This paper presents the design, fabrication and preliminary experimental results of a flexure plate wave (FPW) resonator using sol-gel derived lead zirconate titanates (PZT) thin films. The resonator adopts a two-port structure with reflecting grates on the composite membrane of PZT and SiNx. The design of the reflecting grate is derived from a SAW resonator model using COM theory to produce a sharp resonant peak. The comparison between the mass and the viscosity effects from the theoretical expression illustrates the applications and the constraints of the proposed device in liquid sensing. Multiple coatings of sol-gel derived PZT films are adopted because of the cost advantage and the high electromechanical coupling effect over other piezoelectric films. The fabrication issues of the proposed material structure are addressed. Theoretical estimations of the mass and the viscosity effects are compared with the experimental results. The resonant frequency has a good linear correlation with the density of low viscosity liquids, which demonstrate the feasibility of the proposed device.