In-plane microactuator for fluid control application

We introduce a new approach that alters the local flow condition using electrostatically driven microactuator moving in the in-plane direction such that form drag of the actuator can be eliminated. This is in contrast to the electromagnetically driven microflap moving normal to the substrate. A 60 /spl mu/m/spl times/200 /spl mu/m plate moving parallel to the substrate surface induces a "spanwise velocity" into the flow field. This spanwise velocity, when applied to the near-wall streaks, increases the transport of high-speed fluid away from the wall, therefore causing reduction in viscous drag. The microplate is attached at the end of a microcantilever capable of, even in non-resonance, large tip deflection (>100 /spl mu/m), tested at the operation frequencies of 500-1200 Hz. The cantilever is of a high-aspect-ratio structure (2 /spl mu/m wide, 6-17 /spl mu/m thick silicon) to ensure parallel motion over a long distance and provide robustness against out-of-plane deflection under external disturbances from the flow. We report the design and one-mask fabrication of the in-plane microactuator array made from Silicon-On-Insulator (SOI) wafers and experimental verification of the induced Stoke's flow and a local fluid flow.