Focused Flow Micropump Using Ultrasonic Flexural Plate Waves

Abstract

In this paper, a micromachined pump is presented that uses ultrasonic flexural plate waves traveling along a thin membrane to excite an acoustic field in the fluid that is in contact with the membrane. The acoustic field generates fluid flow by the mechanism of acoustic streaming. A novel combination of radial transducers and unidirectional fluid flow produces a fluid micropump capable of achieving flow speeds up to 1.15 millimeters per second, much faster than flow speeds previously obtained. In addition, the radial transducers successfully focused 2-micron polystyrene spheres over a beam waist of less than 100 microns. Also presented are techniques used to characterize thipt>