A rotating permanent magnetic actuator for micropumping devices with magnetic nanofluids

In this study, a novel rotating permanent magnetic actuator (PMA) system is proposed to manipulate magnetic nanofluids to pump chemicals inside micro-sized channels with circular paths. The PMA consists of two permanent magnet pairs and a rotor-like structure. A semicircular-shaped microchannel with a square cross-section area is located at the top of the actuator in order to investigate the performance of the PMA. Fe3O4-water magnetic nanofluid is employed as a working fluid for the manipulation inside the microchannel. In the first stage of this work, a numerical survey is conducted to determine the most suitable angular distance between permanent magnets of a pair in terms of generated magnetic field form in the microchannel region and velocity distribution of magnetic nanofluid within the semicircular microchannel when the permanent magnets are stationary. Preliminary experiments are then carried out for the stationary permanent magnets to validate the predicted flow-field results. Performance tests for different PMA speeds (7.5-30 rpm) and particle concentrations (1%-3% by vol.) indicate that it is possible to manipulate the magnetic nanofluid inside the semicircular channel within a velocity range of 58.7-940 mu m s(-1), which corresponds to a flow rate range of 0.56-9.02 mu L min(-1). The results confirm that the proposed PMA system provides flow rate requirements in analytical microfluidic applications such as low flow drug delivery (1-10 mu L min(-1)), cell sorting (6.1 mu L min(-1)), and pathogen detection (3-5.83 mu L min(-1)).