MEMS-based Air Turbine with Radial-inflow Type Journal Bearing

A microelectromechanical‐systems (MEMS)‐based air turbine with a new bearing system was designed, fabricated, and evaluated. The bearing system uses a radial‐inflow type journal bearing and a single‐sided hydroinertia thrust bearing. To fabricate the radial‐inflow type journal bearing, cavity‐through deep reactive ion etching (DRIE) in conjunction with silicon‐to‐silicon direct bonding was used. Two etched silicon substrates were directly bonded, and then the bonded silicon substrates were etched by DRIE through the inside cavities. A maximum rotation speed of 95 000 rpm was achieved. The measured and calculated frequency responses of the rotor‐bearing system suggest that the maximum rotation speed was probably limited by the pitching mode resonance. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.