Design of electrostatic actuated MEMS biaxial scanning micro-mirror with serpentine structure

In this paper, the design and simulation fabrication of MEMS biaxial scanning parallel plate type micromirror with serpentine beams is described as having different folded beam dimensions. This scanning micro-mirror is an optical device used to steers and reflects incident light along with 1-D and 2-D with an angular rotation by 1° scan angle i.e. displacement of ∼43 µm of the mirror. It is applicable in coherence tomography, light projection, non-linear optics, optical switch, confocal microscopes, LiDAR etc. Electrostatic actuation in 2-D scanning micromirrors has a gimbal configuration and work on the principle of electrostatic forces between pairs of movable and fixed electrodes. However, a larger mirror dimension (∼5mm) results in a large electrodes gap which further requires a higher driving voltage to achieve the desired scan angle. To reduce the driving voltage, the straight torsion springs which connect the mirror to the gimbal are replaced by serpentine structures. The effects of pull-in voltage and resonant frequency in the order of 1 KHz straight torsion and serpentine beam on MEMS micromirror having a dimension of 5000 μm were studied.