Piezoelectric transducers for nebulizer application

Abstract

This thesis presents the study on new liquid nebulizer devices which are based on ultrasonic horn transducers driven by different types of piezoelectric ceramics. The design of the nebulizer device mainly includes two parts, the studies on materials and the transducer structures. The material fabrication, property measurements and resonance characterization of piezoelectric ceramics, including lead zirconate titanate (PZT) and two types of lead-free ceramics (Ba0.95Sr0.05)(Ti0.95Zr0.05)O3 (BSZT) and (Na0.5K0.5)NbO3 (KNN) are presented and discussed. Theoretical studies of the ultrasonic horns and simulations of stepped horn transducers by finite element method are included in this thesis. Experiments of displacement and electrical impedance measurements are conducted to evaluate the performances of these transducers. Finally, the nebulization tests of the device prototypes based on different piezoceramics have been performed. Original contributions reported in this thesis include: 1. A new, small in size, orientation controllable nebulizer prototype has been designed and fabricated. The nebulizer is driven by a PZT ceramic ring and works under an AC voltage equal to or higher than 27V in amplitude. 2. A hard type lead-free ceramic KNN ring has been deployed in the nebulizer as a substitute of PZT ceramic. The lead-free nebulizer functions well but requires higher driving voltage comparing with the PZT-based ones. 3. A stepped horn transducer based on lead-free piezoelectric ceramic disk (BSZT) has been developed. It has a good displacement performance which is comparable with PZT based ones.