Date of Graduation

2004

Document Type

Thesis

Degree Type

MS

Committee Chair

Lawrence Hornak

Abstract

Microelectromechanical systems (MEMS) are electrical and mechanical components scaled down to the micrometer scale and integrated on a common substrate. These devices can be batch fabricated and are capable of functioning individually as well as in arrays. With the growing applications of MEMS in safety critical applications, there is an absolute need for their increased reliability. In order to study and improve the reliability of MEMS as well as enable the prediction of faults, a thorough knowledge of the dynamic behavior of these microstructures is required. Prediction of the dynamic behavior of the microstructures is a challenging task and requires the development of a reliable mathematical model. Prior work by the research group involved a through-wafer optical method of monitoring and characterization of lateral motion of a comb resonator. This method was inadequate to characterize its out of plane motion. In order to support the out of plane characterization of the comb resonator with a separate effort, there was a need to design and test independently a MEMS device which had a predominant out of plane motion. The work presented in this thesis involves modeling, designing and characterization of the dynamic behavior of an electrostatically actuated parallel-plate actuator which, because of its inherent out-of-plane motion, can be monitored using a laser doppler vibrometer. In order to simulate a real-time fault which may occur due to particulate contamination, fractures or spring softening, structures with varying mass and spring constants were designed. The structures were fabricated through the Multi-User MEMS Processing Service (MUMPS) provided by MEMSCAP, formerly Cronos Integrated Microsystems. The actuator designed consists of two parallel square plates separated by a gap of 2 microns with the lower plate fixed and the upper plate suspended by crab-leg springs. The dynamic behavior of the actuator was modeled in Simulink and tested experimentally by a laser doppler vibrometer. Position and phase variation with frequency (with respect to the drive signal) is studied as a function of plate mass and spring constant in an air ambient. The designed actuator acts as an over damped oscillator with compressibility effect of the air squeeze-film observable after 10000 Hz.

Download

Share

COinS