Research on the Performance of a Novel Ferrofluid Linear Pump

Abstract

Fluid transportation is a critical element in the performance of microfluidic “lab-on-a-chip” devices. This paper proposes a ferrofluid linear pump in response to the demand for fluid control in microchannels. The pump comprises two rectangular permanent magnets, ferrofluid, tubes, four one-way valves, and a linear actuator. The ferrofluid is bound in the tube by a strong gradient magnetic field generated by two rectangular permanent magnets, forming a liquid plunger. By driving the permanent magnet through alinear actuator for reciprocating motion, with the cooperation of four one-way valves on and off, the ferrofluid plunger drives the directional flow of fluid materials for stable transportation. The static and dynamic pressure resistance of the ferrofluid plunger is thoroughly analyzed and verified through experiments. The interface profile and static pressure test are consistent with the theoretical results. However, the dynamic pressure test has a significant backflow phenomenon, and the theoretical calculation is no longer applicable. Therefore, an assumption of the backflow channel was proposed, and the relationship between the reciprocating velocity and the equivalent radius of the backflow channel was studied. The research results indicate that as the reciprocating speed increases, the dynamic pressure resistance significantly decreases compared with the static pressure resistance, and the backflow rate increases significantly.

Keywords: ferrofluid, pump, microchannel, static and dynamic pressure