Title :
High Speed Focus Control MEMS Mirror With Controlled Air Damping for Vital Microscopy
Author :
Moghimi, Mohammad J. ; Chattergoon, Krishna N. ; Wilson, Christopher R. ; Dickensheets, David L.
Author_Institution :
Montana State Univ., Bozeman, MT, USA
Abstract :
A high speed focus control microelectromechanical systems (MEMS) mirror with a step response time of 100 μsec and small-displacement bandwidth of 25 kHz is reported for a 3 mm diameter, electrostatically actuated SU-8 membrane mirror. The dominant effect limiting the mirror bandwidth is viscous air damping, and the innovation we describe is the use of a perforated counter-electrode backplate that facilitates air flow underneath the membrane. We have adopted a model, originally developed for a MEMS microphone, to engineer the damping characteristics and design the air hole patterns. Cryogenic deep silicon etching creates through-wafer perforations in the backplate, and fabricated devices achieve wide-bandwidth actuation. The design approach, fabrication process, and dynamic characterization of the MEMS mirrors are shown. Finally, the focus control mirror is used in a confocal microscope for fast axial focus scanning to provide x-z cross-sectioned in vivo images.
Keywords :
cryogenics; damping; electrostatic actuators; etching; high-speed optical techniques; micromirrors; microphones; optical microscopy; silicon; MEMS microphone; MEMS mirror; SU-8 membrane mirror; Si; air hole patterns; axial focus scanning; bandwidth 25 kHz; confocal microscope; controlled air damping; cryogenic deep silicon etching; electrostatic actuator; high speed focus control; microelectromechanical systems; perforated counter-electrode backplate; size 3 mm; through-wafer perforations; vital microscopy; Cryogenic deep reactive ion etching (DRIE); MEMS deformable mirrors; SU-8; high-speed focus control;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2013.2251320
