Exploring polysilicon micromotors for data storage micro disks

This paper presents preliminary results on investigating the use of electrostatically-actuated, polysilicon micromotors for data storage. The polysilicon micromotors examined here are applied as optically-read, ROM devices, with data encoded on the surface of the rotor. Encoding is achieved by etching pits in the surface of the rotor during motor fabrication using RIE. The rotor surface is divided into sectors, each containing tracks encoded for motor diagnostics and data retrieval, providing a mechanism for evaluation of motor dynamics and data storage quality at various radial positions. An open-loop controller has been developed with the objective of operating the salient-pole micromotors at a near constant rotational speed, enabling the encoded information to be read-out via discrete sampling of an optical signal. The controller successfully drives the motor with 12% variation in rotational speed. Open-loop control has been sufficient for reliable data retrieval of bit diameters as small as 5 μm with this speed variation