Active Vibration Control and Isolation for Micromachined Devices

Some harsh environments contain high frequency, high amplitude mechanical vibrations. Unfortunately some very useful components, such as micro-electro-mechanical systems (MEMS) gyroscopes, can be very sensitive to these high frequency mechanical vibrations. Passive micromachined silicon low-pass filter structures (spring-mass-damper) have been demonstrated in recent years. However, the performance of these filter structures is typically limited by low damping. This is especially true if operated in low pressure environments, which is often the optimal operating environment for the attached device that requires vibration isolation. An active micromachined vibration isolator can be realized by combining a state sensor, and electrostatic actuator and feedback electronics with the passive isolator. Using this approach, a prototype active micromachined vibration isolator is realized and used to decrease the filter $Q$ from approximately 135 to approximately 60, when evaluated in a low pressure environment. The physical size of these active isolators is suitable for use in or as packaging for sensitive electronic and MEMS devices, such as MEMS vibratory gyros.