An experimental and numerical investigation into the effects of diffuser valves in polymethylmethacrylate (PMMA) peristaltic micropumps

Utilizing micro-electromechanical systems (MEMS) techniques and a solvent-assisted bonding process, this study fabricates two peristaltic polymethylmethacrylate (PMMA) micropumps. In the first micropump, the actuation chambers are connected via straight microchannels with a uniform width and depth of 500 mu m and 200 mu m, respectively, while in the second micropump, the chambers are connected via tapered microchannels, which function as diffuser valves and yield a net one-way fluid flow. The experimental results indicate that the conventional and diffuser-type micropumps yield maximum flow rates of 262.4 mu l/min and 114.8 mu l/min, respectively. Furthermore, it is shown that the back pressure in the conventional micropump is 3.9 kPa, while that in the diffuser-type pump is 9.2 kPa. The flow rate spectra of the two micropumps are modeled numerically using an electronic-hydraulic analogy. The results obtained for the resonant excitation frequency of the two micropumps are consistent with those observed experimentally (400Hz). However, the flow rate predictions are slightly lower than the experimental values. Furthermore, the experimental flow rate spectrum has a broader bandwidth than the numerical equivalent. The discrepancy between the two sets of results is attributed to the overly simplistic modeling of the actuator-membrane mechanism in the equivalent circuit used to simulate the micropumps. (C) 2008 Elsevier B.V. All rights reserved.