Date on Master's Thesis/Doctoral Dissertation

8-2017

Document Type

Master's Thesis

Degree Name

M.S.

Department

Mechanical Engineering

Degree Program

Mechanical Engineering, MS

Committee Chair

Berfield, Thomas

Committee Member

Richards, Christopher

Committee Member

McNamara, Shamus

Author's Keywords

piezoelectric; harvester; bistable; buckled; nonlinear; MEMS

Abstract

A novel energy harvesting device design is presented to be created via microfabrication techniques. Such devices have countless applications for powering low-current electrical devices, especially wireless sensors or transmitters. This micro-electromechanical system (MEMS) design utilizes the piezoelectric response of a bistable buckled beam to gather electrical energy via ambient vibrations. While many traditional piezoelectric energy harvesters (PEH) consist of simple cantilever beam geometries, this nonlinear design utilizes inertial effects of torsional lever arms to actuate a central buckled beam to snap between its two stable states; such an abrupt strain on the piezoelectric beam potentially produces a significantly increased electrical response over a wider range of excitation frequencies than is possible with simpler linear systems. The geometries of all structural layers of the device are described in detail, in addition to the cleanroom processes needed to create each MEMS device layer. Experimental fabrication process steps and results, performed by the author's work in the University of Louisville's Micro-Nano Technology Center, are described in detail. The most successful, complete microfabrication process flow is given to the best of the author's abilities. Potential improvements and ideas for future work are given in conclusion.

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