DESIGN, FABRICATION AND CHARACTERIZATION OF MICROMACHINED PIEZOELECTRIC T-BEAM TRANSDUCERS

Open Access
Author:
Zhang, Zheqian
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
June 15, 2010
Committee Members:
  • Christopher Rahn, Thesis Advisor
  • Srinivas A Tadigadapa, Thesis Advisor
  • Donghai Wang, Thesis Advisor
Keywords:
  • multifunctional transducers
  • PZT
  • piezoelectric
  • MEMS
Abstract:
Ferroelectric materials such as PbZr0.52Ti0.48O3 (PZT 52/48) have attractive electromechanical properties for realizing micromachined sensors and actuators because of their large piezoelectric coefficients and electromechanical coupling factors. In this thesis, a MEMS piezoelectric device has been designed and fabricated via direct bulk micromachining of PZT that can be optimized as both an actuator and a sensor. Unlike conventional unimorph and bimorph structures, we present an innovative T-shaped structure in cross-section for these applications. Chapter 1 briefly introduces the development of MEMS technology especially the piezoelectric MEMS transducers and the back ground of our project. Research objectives are also proposed. The conceptual design of the T-beam transducer will be covered in Chapter 2. The Euler-Bernoulli beam theory based mathematical model for prediction of in-plane/out-of-plane displacement and blocking force is introduced. Chapters 3 and 4 are the main contributions of this work and described in detail the design fabrication process, and the performance of the micromachined T-beam transducers. Different process recipes that are developed as part of this work are summarized. These processes can now enable the realization of devices with complex structures such as serpentine flexures from monolithic piezoelectric substrates and open up a large design space for high performance MEMS transducers. The experimentally measured out-of-plane, in-plane, and blocking force characteristics of the devices are described in Chapter 4. Frequency response characteristics of the T-beams are also reported. As a demonstration of the sensing functionality of the T-beam, the fabricated devices have been configured as accelerometers and tested. One of the novel aspects of the device is its sensitivity to acceleration along two orthogonal directions. Chapter 5 summarizes the thesis and suggests future work.