Design and experimental study of a novel three-way diffuser/nozzle elements employed in valveless piezoelectric micropumps

A novel type of three-way diffuser/nozzle element of valveless piezoelectric micropump is presented, and an orthogonal design of the tube is done by computational fluid dynamics. Comparison of the simulation results between the traditional diffuser/nozzle element and the three-way diffuser/nozzle element shows that the latter has a better performance. The λ defined as the ratio of the total pressure loss coefficient for flow in the negative direction to that in the positive direction of the novel element is 1.2 and 16 % larger than that of the former traditional one as Δp = 10 kPa and Δp = 50 kPa, respectively. Then a three-way diffuser/nozzle element is fabricated, and the experiment is carried out. The results show that the simulation results are in good agreement with the experiment results. The maximum differences between the simulation and experiment are 6.23 % at Δp = 20 kPa in the negative direction and 3.53 % at Δp = 100 kPa in the positive direction when the pressure differences are given from 10 to 100 kPa. The micropump is fabricated, and the experiment results show that the maximum flow rate and back pressure are 0.451 ml/min and 3.11 kPa with the frequency of 225 Hz when the sinusoidal voltage is 100 VP-P.