Electrostatically levitated spherical 3-axis accelerometer

MEMS-based electrostatically levitated spherical 3-axis accelerometer has been developed. Fabrication of the spherical MEMS device is made possible by incorporating Ball Semiconductor technology and a novel sacrificial etching process utilizing xenon difluoride gas etching through gas permeable layer. 1-millimeter diameter spherical proof mass is completely suspended without any mechanical support by closed-loop controlled electrostatic forcers. 3-axis acceleration is derived from intensity of servo feedback between capacitive position sensing and the electrostatic actuation. Noise floor is estimated as 40/spl mu/G/Hz/sup 1/2/ level. After calibrating geometrical misalignment, scale factor and zero-G offset errors, linear output with minimal cross-axis error is obtained.