Understanding Smart Sensors - Nomads.usp

MEMS Beyond Sensors 211Figure 9.8 A single-piston microsteam engine. (Courtesy of Sandia National Laboratories [11].)Suspended diaphragms and freestanding cantilever structures were etched intoepitaxial films using bulk micromachining. The cantilever beams deflecteddownward due to residual stress variation in the film. Surface micromachiningtechniques were also applied to amorphous SiC. A 150-mm-diameter,1.5-mm-thick gear was fabricated from amorphous SiC sputtered on silicondioxide. Those materials hold promise for MEMS devices but require considerabledevelopment effort to progress from the laboratory into production.9.3 Other Micromachined StructuresIn addition to actuators, MEMS structures will be used for system componentsthat require small size or reproducibility that can be achieved with micromachining.Multiple, metal microgears have been driven by forced air orrelatively weak magnetic fields. Other examples discussed in this section demonstratethe variety of research and development activity that is occurring forMEMS-based devices.9.3.1 Cooling ChannelsA microheat pipe created by parallel microchannels in the bottom of ahigh-performance IC can provide cooling to minimize hot spots, improve