Integrated flow sensor for in situ measurement and control of acoustic streaming in flexural plate wave micropumps

This paper presents the design, fabrication, and characterization of a micromachined flow sensor, which is integrated onto the flexural plate wave (FPW) micropump. The flow sensor and the FPW micropump represent a complex microfluidic system that is able to control the fluid flow in the device. The system was designed using a commercial software package. The microfluidic system of a size of 10 x 10 mm was fabricated using common fabrication techniques. The micropump is made of an aluminum, piezoelectric zinc oxide, polysilicon. and low-stress silicon nitride membrane with a typical thickness of 1-3 mu m, The thermal flow sensor consists of a polysilicon heater and polysilicon-aluminum thermopiles as temperature sensors. The cold junctions of the thermopiles are located in a new design that will avoid the drift effect of the flow sensor, The results show expected flow velocity-drive voltage characteristics. (C) 2000 Elsevier Science S.A. All rights reserved.