Unidirectional and bidirectional valveless electromagnetic micropump with PDMS-Fe3O4 nanocomposite magnetic membrane

In this paper, a nozzle-diffuser electromagnetic micropump with nanocomposite magnetic membrane for sub-microliter pumping applications is presented. The membrane included magnetite (Fe3O4) nanoparticles dispersed in a layer of polydimethylsiloxane (PDMS). Fe3O4 as a nontoxic and environmentally friendly material with excellent magnetic properties is used for the first time in the fabrication of an electromagnetic micropump. In order to achieve the most biocompatibility, PDMS is applied in most parts of the micropump. Lack of control on the recovery time of the membrane is one of the most important disadvantages of the proposed micropumps in the literature. This weakness causes an imbalance between the supply and pump mode of the micropumps leading to an undesirable performance of both of these. To address this issue, a bidirectional electromagnetic micropump is presented in this paper. In this system a secondary magnetic field is applied to equalize the response and recovery time of the membrane. Using this novel micropump, the maximum flow rate of 1.25 mu l min(-1) at the frequency of 0.1 Hz has been achieved. To indicate the best performance conditions for the micropump, effective parameters on the micropump performance were examined. These parameters include the size of the microchannels, electric current, number of coil turns, concentration of the Fe3O4 nanoparticles and frequency.