Flow control by using high-aspect-ratio, in-plane microactuators

Abstract The successful design, modeling, fabrication, and testing of high-aspect-ratio large deflection in-plane microactuators are presented. The large displacement, in-plane actuators have a unique application in the area of fluid flow control. Unlike previously used electromagnetically actuated microflap in which motion was normal to the substrate, we introduce a novel design that alters the local fluid flow by moving the actuators parallel to the substrate. This new approach of `in-plane motion' allows for a condition free of `form drag'. Furthermore, electrostatic drive allows for lower power consumption (μW). The actuator includes microplates that are 60×200 μm 2 . These microplates, when moved parallel to the substrate surface, induces a `spanwise velocity' into the flow field above them. This induced velocity field, when applied to the near-wall streaks (regions of high shear drag), would increase the transport of high-speed fluid away from the wall, therefore causing reduction in viscous drag. The actuators are made from silicon-on-insulator (SOI) wafers using a one mask deep reactive-ion-etching (DRIE) process. The microplates are suspended by a high-aspect-ratio cantilever structure (2 μm wide, 6–18 μm thick silicon) to ensure robustness against any disturbances in the out-of-plane direction. We present experimental verification of both the induced Stoke's flow and a local fluid flow created by our in-plane microactuators.