Study On PZT Piezoelectric Thin Film Micro-actuator

Micro actuator, as the important MEMS component, has become the research focus in Micro-Electronic Mechanical Systems (MEMS) field. Piezoelectric actuators translating electric energy into mechanical energy using the reverse piezoelectric effect, have been widely used in ultrasonic testing, precision displacement , positioning controlling, acoustic and mechanical testing field duo to its simple structure, fast response, high-frequency applicability, simple circuit of driving and handling.In this dissertation, only the piezoelectric bimorph micro-actuator and valveless piezoelectric micro pump are introduced. Based on the existing problems of two actuators above, piezoelectric bimorph actuators with reasonable structure, simple manufacture process and excellent driving ability, and piezoelectric valveless micro-pump with stable performance, low driving voltage, and easy control are manufactured by means of reasonable choice of micro-fabrication processing and materials. The works carried out can be mainly summarized as follows:1) Preparation of piezoelectric film synthesized by hydrothermal method and its characteristics study. In this dissertation, the process of PZT thin films prepared by hydrothermal method and its characteristics are all studied in details. Phase structures and surface morphology of PZT film are analyzed by XRD and SEM; Film thickness is measured by the CCD equipment and density is calculated. Furthermore, the relationships between the growths rate of film as well as weight increment and growth times; At last, ferroelectricity and polarization direction of PZT film are also studied. PZT film synthesized by single process hydrothermal method and its characteristics are also researched. And its results are compared with those of PZT film synthesized by hydrothermal method.2) Structure optimization, preparation and driving ability of PZT thin films piezoelectric bimorph actuator are researched in this dissertation. To prepare piezoelectric bimorph driver with good performance and adaptation to the micro-assembly , the relationships between the sizes of structure and its driving performance are simulated by Finite Element Analysis (FEA) software ANSYS; Based on the results of simulations, the size of bimorph is fixed. PZT thin films piezoelectric bimorph actuator is prepared by hydrothermal method and micro-processing technology. 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 is obtained. Eventually, piezoelectric actuator with the best driving ability is prepared.3) Piezoelectric valveless micro-pump theoretical analysis, prototype preparation and its performance are studied. The working principle of the micro-pump and micro-pump fluid flow characteristics, which provides a theoretical basis for choice of micro-pump basic parameters, is theoretically analyzed. After preparation of pump and PDMS pump membrane...