A novel revolving piston minipump

Abstract

In this study, a novel prototype high-efficiency miniature pump that uses magnetic properties of a ferrofluid in both pumping and valving mechanisms is presented. The minichannel consisting of a cylindrical pumping chamber, a check valve, an inlet and an outlet, comprises six bonded layers of PMMA. A cylindrical permanent magnet that is placed inside the chamber and is externally actuated by a motorized off-center permanent magnet, functions as a revolving piston which sweeps the perimeter of the cylinder. Ferrofluid is used to cover the gaps between the magnetic piston and the channel walls, also serves as a separating plug between the inlet and the outlet of the chamber preventing recirculation of the pumped fluid inside the chamber. This novel revolving piston design eliminates the need for an inlet valve. Pressure head is maintained using one ball check valve at the outlet of the pump. Water has been successfully pumped at flow rates of up to 934μL/min, backpressures of up to 994Pa, and maximum achieved volumetric efficiency of 79 percent while working at 80, 52, and 9rpm rates, respectively.