Configuration design of piezo actuator for Hollow tube type micropump

We have proposed a hollow tube type micropump which integrates a liquid flow driving part such as a PZT piezoelectric material and a tube part. And the flow function demonstrated by the hollow tube type micropump was evaluated and it is confirmed that the flow velocities by the pump were increased and decreased. We examined the improvement of the pump. Here, it is effective to give a large vibration to a liquid inside in the hollow tube to increase a liquid volume change of the hollow tube type micropump as the flow ability. Therefore, it is necessary for the actuator to improve the amount of the vibration displacement. In this report, two kinds of piezoelectric analyses were preceded in order to make the micropump high performance. The analytical code used is general-purpose finite element analysis software ANSYS. First of all, the shape of PZT to increase the amount of vibrating displacement for the piezo actuator was analyzed statically. The shapes (1) ring type, (2) trench type on the ring, and (3) C shaped type are investigated. As for trenched type PZT, a quadrangle trench was carved for an outer surface on ring type PZT at equal intervals. And C shaped PZT, the slit has been added to ring type PZT. Moreover, the hollow tubes of titanium are also included in all cases for this analysis. As a result, a trenched type PZT was the best shape to improve the maximum vibration displacement compare with its ring type PZT. Moreover, a C shaped PZT is effective in case of repeatable use for an actuator. Finally, we searched for the best driving conditions of the actuator by using a dynamic piezoelectric analysis at the resonant frequency, when ring type PZT was used as analytical model. As the result, in the first mode, the high vibration displacement was obtained partially at the first-mode, however, it was confirmed in the higher-order mode that the vibration displacement was transformed uniformly into the direction of the inner side of the tube. Therefore, the vibration displacement is comparatively small, however, it is effective that the amount of the vibration displacement at the resonant frequency should be controlled in the higher-order mode. However, when the transformation of PZT shows complex transforming behavior like the inverse deformation mode, the possibility of influencing the flow functionality harmfully is presumable. Therefore, the improvement of a further flow functionality is suggested in combining and using modes other than the repeated inverse deformation mode.