Design of ring type trench PZT for tube type micropump by using FEM analysis

Recently, micropump for liquid transportation is actively researched. However, the existing micropump is separated into a flow part and a pump part, and miniaturization of device has been difficult due to the complex design of the flow part. Therefore, we developed a tube type micropump which is the integration of the flow part and the pump part. This micropump mimics the peristaltic motion of angleworm by setting several ring type PZT in equal intervals on the hollow tube. By adding AC voltage to the PZT, the PZT vibrates, and the vibration of PZT will be transmitted to the liquid in the hollow tube. That enables the tube type micropump to transmit liquid. Though the flow performance of tube type micropump was confirmed from flow experiments, flow rate of pump was extremely small. In order to increase the flow rate of pump, power of PZT is important. Therefore, we need to increase the PZT displacement and PZT generated force which can transmit PZT vibration. Here, we have confirmed that the displacement of PZT increased by adding rectangle trenches on ring type PZT by using static piezoelectric analysis. However, stress concentration occurs on the bottom surface at rectangle trench. Moreover, generated force of ring type PZT could not be researched by FEM analysis. In this study, PZT conditions which are able to increase displacement and generation force were investigated. Also, stress state of trench type PZT was researched. As a result, the displacement decreased by increasing PZT thickness while generated pressure increased. Generated pressure was the biggest in inner trench model and maximum equivalent stress of inner trench model is lower than other trench ring type PZT. Moreover, displacement and generated pressure increased by increasing the trench number. Therefore, ring type PZT which has many trenches at inner area is effective as a pump actuator.