Dissertation Title: High Quality-factor Gigahertz Micromechanical Resonators for Efficient On-chip Ultrasonic Manipulation
Date: 2024/05/22 - 2024/05/22
Dissertation Title: High Quality-factor Gigahertz Micromechanical Resonators for Efficient On-chip Ultrasonic Manipulation
Speaker: Jingjie Cheng
Time: May 22th from 15:00 p.m.,2024
Location: Room 414A, Longbin Building
Abstract
Micromechanical resonators are core components of micro-elctromechanical systems (MEMS) that transduce mechanical resonance with other various types of energy based on the resonance principle. They have been widely used in consisting of microstructures, microsensors, microactuators, and microelectronics. On-chip ultrasonic manipulation based on micromechanical resonators is an emerging technology that capitalizes on their unique attributes of miniaturized size, high frequency (f), and high quality-factor (Q), to achieve precise control over acoustic signals. This technology holds significant potential in various fields such as wireless communication, quantum information, and biomedical sensing. In recent years, researchers have made remarkable progress in developing on-chip ultrasonic manipulation systems by meticulously designing and optimizing the structures of micromechanical resonators. However, a critical and actively pursued scientific challenge revolves around improving the Q by reducing the resonant energy losses incurred within these high-frequency micromechanical resonators. By effectively addressing this challenge, it becomes possible to significantly enhance the efficiency and accuracy of ultrasonic manipulation, thereby meeting the escalated demands for high-speed, high-resolution, and high-sensitivity requirements in related applications. In this dissertation, different types of gigahertz (GHz) frequency micromechanical resonators are designed and fabricated, and different dissipative suppression strategies are adopted to improve the Q, including reducing acoustic impedance mismatch, interface mismatch, and anchor loss.
Biography：
Jingjie Cheng received the B.S. degree in Measurement and Control Technology and Instrumentation from Xidian University in 2019. She is currently a Ph.D. candidate at the UM-SJTU Joint Institute, supervised by Prof. Lei Shao. Her current research interests include GHz micromechanical resonators, ultrasonic imaging and sensing.