Investigation of a piezoelectric valveless micropump with an integrated stainless-steel diffuser/nozzle bulge-piece design

To meet a growing need in biological and medical applications, innovative micro-electro-mechanical system (MEMS) technologies have realized important progress on the micropump as one of the essential fluid handling devices to deliver and control precise amounts of fluid flowing along a specific direction. This research proposes a piezoelectric (PZT) valveless micropump adopting an integrated diffuser/nozzle bulge-piece design. The pump mainly consisted of a stainless-steel structured chamber with dimensions of 8 mm in diameter and 70 mu m in depth to enhance its long-term reliability, low-cost production, and maximized liquid compatibility. A PZT diaphragm was also used as a driving source to propel the liquid stream under actuation. As commonly used indices to describe pump operation, the delivered volumetric flow rates and pressures were determined at bulge-piece diameters of 2, 4 and 6 mm, with a driving voltage of 160 V-pp and frequency ranging from 50 to 550 Hz. Measurements and simulations have successfully shown that this micropump is capable of operating at a greater volumetric flow rate of up to 1.2 ml min(-1) with a maximum back pressure of 5.3 kPa. In addition, the time-recurring flow behavior in the chamber and its relationship to the pumping performance were examined in detail.