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

The successful design, modeling, fabrication, and testing of high-aspect-ra tio large deflection in-plane microactuators are presented. The large displ acement, 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 t hat alters the local fluid flow by moving the actuators parallel to the sub strate. This new approach of 'in-plane motion' allows for a condition free of 'form drag'. Furthermore, electrostatic drive allows for lower power con sumption (mu W). The actuator includes microplates that are 60 x 200 mu m(2 ). These microplates, when moved parallel to the substrate surface, induces a 'spanwise velocity' into the flow field above them. This induced velocit y 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, ther efore causing reduction in viscous drag. The actuators are made from silico n-on-insulator (SOI) wafers using a one mask deep reactive-ion-etching (DRI E) process. The microplates are suspended by a high-aspect-ratio cantilever structure (2 mu m wide, 6-18 mu m thick silicon) to ensure robustness agai nst any disturbances in the out-of-plane direction. We present experimental verification of both the induced Stoke's flow and a local fluid flow creat ed by our in-plane microactuators. (C) 1999 Elsevier Science B.V. All right s reserved.