Single-disk and double-disk viscous micropumps

The development and testing of two versions of a novel micropump are described: (i) the single-disk viscous pump and (ii) the double-disk viscous pump. The rotational movement of the disk(s) induces viscous stresses on the fluid that forces the fluid from an inlet channel, and then, through the pumping volume above the single disk, or between the two disks. A wiper acts to “wipe” the fluid from the disk(s) toward the outlet channel. The fluid flow through the double-disk pump is visualized using a red Rhodamine dye that is injected into the fluid passage upstream of the pumping volume. These visualizations provide information on the relative importance of viscous forces, centrifugal forces, and static pressure variations. The maximum flow rates and pressure rises are 1.0 ml/min, 643 Pa, and 2.1 ml/min 1.19 kPa for the single-disk and double-disk pumps, respectively, for a rotational speed of 5000 rpm, a disk diameter of 2.38 mm, and a gap height of 103 μm, and supplied power to the motor of 7 W. The disk pumps are fabricated using precision machining techniques employed on a lathe and milling machine. Advantages of the viscous disk pumps include: simplicity of design, planar structure, continuous flow, well controlled flow rate, and, if desired, the ability to augment mixing in the fluid.