A valveless piezoelectric micropump with a Coanda jet element

•We present a valveless piezoelectric micropump with a Coanda jet element.•The volume efficiency of the micropump changes linearly with the Reynolds number.•The vortex plays an important role in the flow in the Coanda jet at high frequency.•The ratio of flowrate changes with back pressure varies inversely with frequency.

A valveless piezoelectric micropump with a Coanda jet element is designed and fabricated by the precision machining and thermally bonding. The micropump can transport fluid at low Reynolds numbers due to the Coanda effect causing the flowrate difference between the inlet and outlet channels. The numerical simulations have been carried out for studying the flow characteristics of the micropump. The numerical results show that the flowrate and volume efficiency of the micropump reach 0.259 ml/min and 0.227, respectively, at the Re0 of 300 and frequency of 2 Hz. The flow fields in the micropump at the low and high frequencies are strikingly different due to the vortex induced by the dramatic flowrate changes. The flowrates and back pressures of the micropump are measured at different frequencies and voltages. The experimental results show that the flowrate and back pressure can reach 0.201 ml/min and 1.56 kPa, respectively, at the voltage of 360 Vp-p and frequency of 10 Hz.