Energy Loss Mechanisms in Micromechanical Resonators

Dr. Julie Zhili HaoAssistant ProfessorDepartment of Mechanical EngineeringOld Dominion UniversityNorfolk, VirginiaABSTRACT
Micromechanical resonators are of great interests for a wide range of applications, such as rotation rate sensors (gyroscopes), electrical filters, and physics research instruments. For their practical applications, quality factors (Q) or energy loss mechanisms of micromechanical resonators are of critical importance, as a higher Q in these devices translates to higher sensitivity, lower motional resistance, better stability, and lower power consumption. Therefore, it is desirable to design and fabricate micromechanical resonators with ultra-high Q or very little energy loss. To this end, we need to understand and analyze energy loss mechanisms in such devices, not only for improving their performance, but also for establishing the fundamental limit of the Q. In fact, arising from its own nature, each loss mechanism in a micromechanical resonator exhibits a unique phenomenon that is governed by its related theory and can be analytically expressed and experimentally characterized. In this talk, I will discuss the analytical and experimental study on support loss and thermoelastic damping (TED) in micromechanical resonators. From this study, the closed-form expressions for their quantitative evaluation are obtained, shedding significant insights into the geometrical design and choice of materials in high-Q micromechanical resonators.BIO
Julie Z. Hao received the B.S and M.S. degrees in Mechanical Engineering from Shanghai Jiao Tong University, Shanghai, in 1994 and 1997, respectively. She received her doctoral degree in Mechanical Engineering from the University of Central Florida in 2000. Her dissertation topic was the research and development of a MEMS-based cooling system for microelectronics. After graduation, Dr. Hao worked as a MEMS Engineer in industry for two years and was involved in the development of optical MEMS and microfluidic products. From 2002-2006, she worked in the Integrated MEMS Laboratory at the School of Electrical and Computer Engineering, Georgia Institute of Technology. In July 2006, Dr. Hao joined the Department of Mechanical Engineering, Old Dominion University. Her research focuses on the development of MEMS devices for sensory, biomedical, and communications applications. These include high precision gyroscopes, bulk-mode resonators, high-Q biosensors, as well as microfluidic devices. Also, Dr. Hao works on the analytical and experimental study of complex multidisciplinary micromechanics that is critical for the performance of MEMS devices and microsystems.

Location: Laufer Library, RRB 208

Audiences: Everyone Is Invited

Contact: April Mundy