A novel hydrodynamic suspension micropump using centrifugal pressurization and the wedge effect

The micropump is the heart of microfluidics systems. However, for mechanical micropumps, bearing wear failure has been a major obstacle to performance and reliability. Hydrodynamic suspension, which can make the rotating components levitate in liquid without any mechanical friction, is applied to break this bottleneck. In this paper, a novel kind of hydrodynamic suspension micropump (HSMP) without a grooved thrust bearing is proposed. Based on the centrifugal effect, the HSMP uses a rotating rotor to accelerate and pressurize adjacent fluid, and thus reacting forces are generated on the rotor surfaces to levitate it. The mechanisms of suspension forces formation, the centrifugal effect and the wedge effect in the liquid films near the rotor are identified using theoretical analysis and simulation. The variation in suspension forces with rotor position is investigated, revealing that the suspension bearings of the HSMP, similar to a spring damper, can self-adjust suspension forces along with a change in rotor position. Moreover, the suspension stiffness is positively correlated with the rotating speed. The HSMP prototype designed herein, whose overall size is only 34 mm × 34 mm × 31 mm, can provide a maximum output performance of 3230 mL/min and 96.3 kPa at 20000 r/min, which is manyfold greater than other micropumps. The proposed HSMP is demonstrated to be more powerful with a simple structure, high power density, and high reliability.