MEMS Air-Damped Isolator for Dual-Axis Micromirrors: Broad-Range Frequency Vibration Isolation

• Published in: Journal of microelectromechanical systems Vol. 34; no. 3; pp. 260 - 267
• Main Authors: Ran, Longqi, Zhou, Wu, He, Jiangbo, Wu, Jiahao, Wang, Yan, Gong, Xuhui
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Coils; Control systems; Couplings; Damping; Degrees of freedom; Design; Dynamic response; Frequency ranges; isolator; Isolators; Laser doppler vibrometers; Microelectromechanical devices; Micromirrors; mirrors; Resonant frequency; Shock absorbers; Springs; Stiffness; Structural design; Substrates; Vibration isolators; Vibration tests; Vibrations
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2025.3543166

The fracture failure of dual-axis micromirrors under the AEC-Q100 qualification test could not be mitigated by structural designs alone due to the need for compatibility in bending and torsional stiffness. To address this, a passive MEMS vibration isolator was proposed to protect the micromirrors within a broad frequency range of 20 Hz to 1200 Hz, unlike conventional designs limited to a fixed frequency. The proposed method was based on a two-degree-of-freedom (DOF) micromirror-isolator system, in contrast to the single-DOF systems employed in existing methods. The isolator's stiffness was matched to the micromirror's stiffness to maximize the mirror plane's movement, and an air damping mechanism was incorporated using a <inline-formula> <tex-math notation="LaTeX">20~\mu </tex-math></inline-formula>m gap to control the dynamic response time. The designed isolator was fabricated using a novel SOI-on-glass process and tested on a high-precision vibration shaker equipped with a laser Doppler vibrometer. Results showed that the proposed isolator attenuated vibration amplitude by 25.55 dB, closely aligning with the design value of 24.89 dB. Additionally, an automotive-grade vibration test demonstrated successful isolation under a 50g vibration within the 20 Hz to 1200 Hz frequency range, without introducing parasitic modes that could disrupt the micromirror's operational modes.[2024-0220]