Effect of valve holes spacing on bubble retention in micro-piezoelectric pump

Bubble retention in the pump chambers weakens the stability and reliability of micro-piezoelectric pump sharply. As the valve holes spacing has a critical impact on the fluid flow field distribution, which affects the bubbles detained in pump chamber moving, it is essential to study the disciplines about influence that valve holes spacing has on bubble retention. Firstly, the relationship between bubble retention and micro-piezoelectric pump output performance had been analyzed from equivalent bulk modulus of fluids. Then, through the friction drag, the disciplines about influence that valve holes spacing has on bubbles moving were analyzed, to obtain the effect that valve holes spacing has on bubble retention. Finally, the bubble retention experiments were carried out. Experimental results indicated that output performance of micro-piezoelectric pump with the minimum valve holes spacing (15.2mL/min, 10.4kPa) is apparently superior than the one with the maximum spacing (14.6mL/min, 7.0kPa). While bubbles were injected, pump with the maximum spacing can exclude the detained bubbles, but the output performance fluctuated greatly. In contrast to the pump with the maximum spacing, the output performance of pump with the minimum spacing fluctuates slightly, but the small bubbles are difficult to be completely excluded, due to the floating dead zone.