Electromechanical transduction is an important component of microelectromechanical systems (MEMS), a technology with wide-ranging applications, including mobile computing, sensors, energy harvesting, and displays. These disparate applications have varying performance requirements, but generally transduction efficiency, mechanical precision, response time, cost, compatibility with photolithography and other fabrication processes, and operability at micro-scale are all desired metrics for MEMS devices. Piezoelectric transduction provides substantial advantages, including precise displacements, quick response times, and high transduction efficiency. These strengths make piezoelectric transduction particularly well-suited for use in resonators, sensors, and energy harvesters. However, piezoelectric transduction also produces much smaller magnitudes of movements than other electromechanical transduction mechanisms, such as thermal or capacitive. This limits the utility of piezoelectricity in designing MEMS actuators. Currently, MEMS designers compensate for this limitation by using sophisticated structures to amplify the small strains produced through the reverse piezoelectric effect. One of the oldest and simplest such designs is the bimorph cantilever beam. Comprised of two distinct, but mechanically connected, piezoelectric layers, the beam uses piezoelectricity to cause longitudinal strain in both layers. As one layer expands, the other contracts—this opposing motion creates a bending moment, causing the beam to deflect out-of-plane, often at substantially higher displacements than the expansion or contraction of either piezoelectric layer. This thesis presents a design and simulation results for a unimorph beam comprised of only one piezoelectric layer. Through use of a novel electrode pattern that applies a non-uniform electric field, this beam acts as a quasi-bimorph, creating a bending moment without the need for two distinct piezoelectric layers.
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Master of Science in Electrical Engineering (M.S.E.E.)
College of Engineering and Computer Science
Electrical and Computer Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Chan, Kevin, "Design of Unimorph Out-of-Plane Piezoelectric Actuator" (2019). Electronic Theses and Dissertations, 2004-2019. 6825.