Design and Characterization of Valveless Impedance Pumps

Abstract

ABSTRACTThis study designs, fabricates and characterizes three valveless impedance pumps, namely a symmetrical pump with a circular cross-section, an asymmetrical pump with a circular cross-section, and an asymmetrical pump with a rectangular cross-section. The pressure head and flow rate characteristics of the three pumps are investigated as a function of the compression location, the compression frequency and the compression amplitude. The experimental results show that the flow is reversible in every case. Moreover, the pressure head is found to be significantly dependent on the actuating frequency, the compression location and the compression amplitude. However, no pressure head is produced when the pinching effect is applied at the center of channel configuration for the symmetrical pump. In the symmetrical pump, a maximum pressure head of 590mm is obtained at a frequency of 26Hz, and results in a flow rate of 0.581/min in the positive direction (i.e. from the left-hand reservoir of the pump to the righthand reservoir). Meanwhile, in the asymmetrical pumps with circular and rectangular cross-sections, respectively, maximum pressure heads of −620mm and −570mm are developed at frequencies of 36Hz and 32Hz, respectively. The corresponding flow rates are determined to be 0.641/min and 0.531/min, respectively. In both cases, the fluid moves in the negative direction (i.e. from the right-hand reservoir of the pump to the left-hand reservoir). Overall, the valveless impedance pumps developed in this study generate a high pumping rate, are easily fabricated and have no moving mechanical valves. As a result, they are eminently suitable for pumping applications in such diverse systems as biomedical devices, fuel cells, PC cooling systems, and so forth.