Preparation of chemically etched piezoelectric resonators for density meters and viscometers

Photolithography and chemical etching were investigated as a potential means of fabricating miniature piezoelectric devices. Among the acids studied, concentrated HCl demonstrated the fastest etching of PZT disks over a wide temperature range. HCl also proved to be compatible with some commercially available photoresists and so could be incorporated into a simple processing procedure for delineating and etching patterns in the ceramic. Using this technique, flexural mode resonators similar to tuning forks were generated with fundamental resonances between 10 and 115 kHz. These devices were then used to provide simultaneous measurements of the density and viscosity of liquids by monitoring the position of the resonance frequency and the width of the resonant peak, respectively.