Surface micromachined turbines

This paper reports the fabrication of three-dimensional microturbines, free from post-processing assembly, using surface micromachining technology. The fabrication process consists primarily of surface micromachining technology, with a bulk micromachining step to create the turbine flow channel normal to the wafer surface. Stress engineering of microstructures (SEMS), utilizing the stress between near-zero-stress polysilicon and high-stress silicon nitride films, was used to devise the structures. Release of the micro-turbines is accomplished through the bottom surface opening, since turbine vanes contain no release holes. The bending force in the turbine vanes simultaneously prevents stiction to the substrate, and allows the vanes to self-form their final shape. Stators, similar to those found in surface micromachined motors, allow electrical sensing or actuation of fluid flow