Investigation of the PZT Actuator in the Micropump Application

• Main Authors: Chen, Shih-Chang, 陳世昌
• Other Authors: Lin, Yi-Cheng
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/68235783353966076306

博士 === 國立彰化師範大學 === 機電工程學系 === 94 === Abstract The lead zirconate titanate (PZT) material acted as an actuator in some microfluidic applications is very suitable. In this dissertation, the PZT bulk actuator is applied to the liquid micropump and microejector. The induced shear deformation of the PZT actuator is employed to deflect and vibrate a diaphragm of a fluid chamber. This shear-type actuator is fabricated by a novel poling design with the poling electrode pair on the same surface. The actuator is made with lateral polarization parallel to the plane, in contrast to the conventional actuator with the polarization along the plate-thickness direction. Due to the requirement for excellent electromechanical coupling characteristics, the samples poled under various poling conditions, including the poling voltage, poling temperature and poling duration, were tested and compared to determine the optimum conditions. Before poling process, the distribution of electric field in the sample during poling was simulated using commercial finite element method (FEM) software to predict the appropriate poling voltage. The unique “push by d15 mode” actuating module using beam-shaped shear-type PZT actuator to deflect the diaphragm through a bulge is analyzed. The analytical close-form solution for the electrically induced deflection of the beam actuator is formulated. The analytical results are not only compared with the ANSYS FEM solution but also verified by experiment. The actuating module is applied in a micropump or microejector designed with the rectangular pressure chamber and the diffuser as the dynamic passive valve. The components can be nickel-made by UV-LIGA multi-level electroforming technology or silicon-made ones by ICP-DRIE process. The analytical exact solutions for the deflection and volume displacement of the diaphragm without fluid load are derived by the analysis with free-body modeling. The results are also compared with the ANSYS solutions and experiments, which reveals an acceptable agreement. The micropump and microejector prototypes made of silicon or nickel are fabricated and workable. The liquid ejection of the microejector is observed by a visualization setup. The micropump is tested to evaluate the flow performance and frequency response. An equivalent circuit model is developed to deeply understand how the micropump works, and it is numerically solved by PSpice software.