Papers by Author: Wei Jie Dong

Abstract: Methods for measuring the resonant frequencies and visualizing the motion of the Pb(Zr0.5Ti0.5)O3 microcantilever are investigated. Considering the two-segment structure of the microcantilever, a self-exiting self-sensing method is proposed to obtain the fundamental resonant frequency. An optical system consisting of light microscope, CCD camera and video card is established to visualize the first two vibration mode shapes. The theoretical, measured and visualized first resonance of one micocantilever is 17.28 kHz, 17 kHz and 17.8 kHz, respectively. A theoretical second resonance of 84.16 kHz is seen at 71.9 kHz. The proposed method is valid for measuring and visualizing low resonances of active micro structure.

Abstract: This paper aims to make piezoelectric ceramic actuator self-sense its own displacement in the absence of independent sensor. It is derived from the basic piezoelectric equation that the free charge on the wafer of piezoelectric ceramic actuator contains displacement information. So a displacement self-sensing method based on integrate circuit is presented. Voltage driving circuit for the piezoelectric ceramic actuator and integrated circuit for gathering free charge are designed. Based on the proposed compound circuits, the actuator can sense its own displacement while actuation. It is convenient to adjust the circuit and easy to acquire sensitive signal by using this method, and the impedance mismatching problem met in bridge method is overcome. The experimental results show that piezoelectric self-sensing actuator can effectively measure its displacement signal under the conditions of different wave form of driving voltage and different driving voltage frequency.

Abstract: Piezoelectric bimorph fabricated by hydrothermal method is presented in the paper. This method is low cost, simple and easy. In order to describe the characteristics of piezoelectric bimorph, properties of PZT film are studied by XRD and SEM. The ratio of PbTiO3/PbZrO3 in PZT is 53/47, which is around morphotropic phase boundary (MPB). PZT film is composed of cubic particles with the average size of 5μm. Density is figured out through the datum measured in experiments. The model used to analyze the driving ability of bimorph is set up; piezoelectric coefficient d31 of PZT film is worked out using this model. Finally, the ferroelectric property of the bimorph is investigated and coercive voltage of the bimorph Vc =1.67V is obtained.