Abstract
We have been developing a resonantly-driven piezoelectric micropump using active-type check valves in place of conventional passive-type. It actively controls open/close motion of check valves using piezoelectric actuator installed into inlet and outlet. In the previous paper, frequency characteristics of the flow rate without load pressure were investigated using a prototype micropump fabricated with the effective size of 17×8×11(mm)^3. In this paper, load characteristics and bi-directional flow characteristics are experimentally investigated using an adequate timing control for valve closing motion. Maximum flow rate of 65(mm)^3/s and maximum pressure of 0.2MPa are obtained at the driving frequency of 2.8kHz. Besides, it is ascertained that optimal values of phase shift against voltage for driving pump chamber are 15° for inlet check valve and 195° for outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed and a novel micropump with the effective size of 10×10×10(mm)^3 using the shuttle valve is fabricated and tested.
