Micro gears and turbines etched from silicon.

Using silicon etching techniques, free-standing micro gears and turbines were fabricated from silicon. Silicon gears with geometries similar to those of standard watch gears were fabricated, but with outer diameters as small as 300microns. A micro air-turbine was built out of discrete, silicon micro- mechanical components and operated at speeds of approximately 400 rps (24,000 rpm). Surprisingly, the limitations to further size reduction are not the photolithographic or etching processes, but the difficulty in handling such small components without loss or damage.