A novel micromachined vibrating rate-gyroscope with optical sensing and electrostatic actuation

This paper reports the fabrication and preliminary characterization of a no vel vibratory rate-sensor. The sensor employs the modulated integrative dif ferential optical sensing (MIDOS) to detect the output mode amplitude. The mechanical part of the sensor is fabricated by bulk micromachining using a double side anisotropic wet etching process. A CMOS chip containing the det ecting photodiodes and their readout electronics is fabricated through MOSI S. Electrical and mechanical integration of the two parts is achieved by us ing the indium bumps technology. The proof mass is aligned with the detecti ng photodiodes, so that when at rest, equal portions of the two photodiodes are exposed. Several prototypes have been fabricated and tested on a rotat ing table. Good linearity (<1%) was shown on a -1000-1000 degrees/s range a nd so far, a minimum detectable rate (MDR) below 1 degrees/s was demonstrat ed. Future research will focus on lowering the MDR below 0.01 degrees/s. (C ) 2000 Elsevier Science S.A. All rights reserved.