Date of Award


Publication Type

Master Thesis

Degree Name



Electrical and Computer Engineering


electrostatic actuation, LIDAR, MEMS micromirror, PolyMUMPs, repulsive electrostatic actuation, stroke


Arezoo Emadi




A Light Detection and Ranging (LIDAR) system, which is one of the promising technologies for autonomous vehicles, contains many miniature micromachined devices. The micromirror is one of the key components inside the LIDAR system that contributes to the performance of LIDAR. The “stroke” level of the micromirror affects the performance of the micromirror and hence the LIDAR. Therefore, this research focuses on a new approach to increase the level of stroke of the micromirror in an effort to enhance the device properties. In this thesis, four different design configurations of micromirrors are proposed and developed. The proposed micromirrors are based on dynamically-moving capacitor concepts that are actuated using electrostatic actuation. Unlike traditional micromirrors, the developed micromirrors employ three bottom electrodes, which enforces an upward deflection and, therefore, reduces the pull-in instability effect and improves the stroke of the micromirror. Critical design parameters of the micromirror that affect the stroke are studied to develop the four proposed designs. The PolyMUMPs fabrication technique is chosen to fabricate all four proposed micromirror designs. When the micromirror is fabricated using the PolyMUMPs fabrication technique, without any modification in the fabrication steps, the maximum achievable air cavity between the parallel plates is 2.0µm. However, in this thesis, in an unconventional way, the air cavity is increased from 2.0µm to 2.75µm. This is achieved by combining two oxide layers in the fabrication process. In this new design, a high stroke level of 5.07µm is achieved that, in return, will further enhance the performance of the LIDAR. COMSOL Multiphysics software and the MEMS module are used to investigate and analyze the performance of the proposed micromirrors and compare them with conventional MEMS micromirrors.