Fluid-actuated micromechanical structure were designed and fabricated from polysilicon and silicon nitride using surface micromachining techniques. These structures included trains of micromechanical involute-toothed spur gears. The gear diameters ranged from 60 to 1600 um. To increase fluid drive force, rotors were coated with tensile films to induce residual sttresses to delibrately warp them and thereby increase the efficiency of fluid powering by giving them a higher profile. For stuffer strucutres such as gears that must remain planar in order to mesh, vane were added to increase the effectiveness of the fluid drive.
Surface micromachinign was used to integrate flow channel with th emovable structures to assist in their fluid actuation. The entrance regions to the flow channels included on-wafer gaskets to mate with an external flow adapter.
Rotor motion was detected and quantified optically, using an inexpensive phototransistor. Rotor response to flow rate was characterized, and long-term actuation was demonstrated.