A 2-D Micromachined SOI MEMS Mirror With Sidewall Electrodes for Biomedical Imaging

This paper presents a 2 DOF silicon-on-insulator (SOI) microelectromechanical systems (MEMS) mirror with sidewall (SW) electrodes for biomedical imaging. The MEMS mirror is actuated by electrostatic actuators, and the mirror plate is 1000 μm × 1000 μm with a thickness of 35 μm. The paper analyzes the effects of the single-crystal serpentine torsion bar width and bottom electrodes and SW electrodes on the performance of the micromirror. A new fabrication process based on SOI wafer, hybrid bulk/surface micromachined technology, and a high aspect-ratio shadow mask is presented. In comparison to the previous fabrication process and the Optical iMEMS process, the process is novel, easily understood, and simple to realize. Static and dynamic experiments indicate that a MEMS mirror with SW can provide a large scanning angle under low-drive voltage. The MEMS mirror is developed for a confocal MACROscope system for biomedical imaging. This mirror is also well suited for applications where large linear angular scan at low-driving voltage is required.