Understanding Smart Sensors - Nomads.usp

MEMS Beyond Sensors 205PyrexSiliconsubstrateResistorFlexible membraneControl liquidPyrexActual sizeFlow outputFigure 9.1 Microvalve construction and flow path. (Courtesy of Redwood MicroSystems,Inc.)conductor. The meander structure for the conductor and the coil is accomplishedby reversing the normal roles of the conductor and magnetic core. Themagnetic core is wrapped around a planar conductor either by interlacing or byinterconnecting multilevel metal layers. Polyimide is used as the dielectricinterlayer between for embedding the coils and the cores. Figure 9.3 shows thefunctional micromotor and an example of the meander coil [5, 6]. The rotorwas operated up to a speed of 500 rpm based on the limitations of the drivecontroller.Surface micromachining technology has been used to fabricate a micromachinedwedge stepper motor [7]. As shown in Figure 9.4, the outer ring hasinternal teeth, which are engaged by a tooth on each end of the reciprocatingshuttle. The outer ring can have gear teeth on the outside or other means ofengaging another mechanical member. The figure shows a rotary version of thethree-poly layer indexing stepper motor. However, a linear version is possible aswell. This approach can be used in designs that require precise and repeatablepositioning of micromechanical components.