Date of Award

1-1-2011

Document Type

Dissertation

Degree Name

Ph.D.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Siavash Pourkamali Anaraki, Ph.D.

Second Advisor

Corinne Lengsfeld

Third Advisor

Mohammad Matin

Fourth Advisor

James Wilson

Keywords

Frequency, Microelectromechanical system resonator, MEMS, Piezoresistive readout, Self-oscillation, Self-q-enhancement, Thermal actuation, Thermal modeling

Abstract

Over the past decades there has been a great deal of research on developing high frequency micromechanical resonators. As the two most common and conventional MEMS resonators, piezoelectric and electrostatic resonators have been at the center of attention despite having some drawbacks. Piezoelectric resonators provide low impedances that make them compatible with other low impedance electronic components, however they have low quality factors and complicated fabrication processes. In case of electrostatic resonators, they have higher quality factors but the need for smaller transductions gaps complicates their fabrication process and causes squeezed film damping in Air. In addition, the operation of both these resonators deteriorates at higher frequencies.

In this presented research, thermally actuated resonators with piezoresistive readout have been developed. It has been shown that not only do such resonators require a simple fabrication process, but also their performance improves at higher frequencies by scaling down all the dimensions of the structure. In addition, due to the internal thermo-electro-mechanical interactions, these active resonators can turn some of the consumed electronic power back into the mechanical structure and compensate for the mechanical losses. Therefore, such resonators can provide self-Q-enhancement and self-sustained-oscillation without the need for any electronic circuitry. In this research these facts have been shown both experimentally and theoretically. In addition, in order to further simplify the fabrication process of such structures, a new controlled batch fabrication method for fabricating silicon nanowires has been developed. This unique fabrication process has been utilized to fabricate high frequency, low power thermal-piezoresistive resonators. Finally, a new thermal-piezoresistive resonant structure has been developed that can operate inside liquid. This resonant structure can be utilized as an ultra sensitive biomedical mass sensor.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Amir Rahafrooz

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

120 p.

Discipline

Electrical engineering, Mechanical engineering

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