Modeling and analysis of a micromachined piezoelectric energy harvester stimulated by ambient random vibrations

Abstract

Piezoelectric energy microgenerators are devices that continuously generate electricity when they are subjected to varying mechanical strain due to vibrations. They can generate electrical power up to 100 µW which can be used to drive various sensing and actuating MEMS devices. Today, piezoelectric energy harvesters are considered autonomous and reliable energy sources to actuate low power microdevices such as wireless sensor networks, indoor-outdoor monitoring, facility management and biomedical applications. The advantages of piezoelectric energy harvesters including high power density, moderate output power and CMOS compatible fabrication in particular with aluminum nitride (AlN) have fuelled and motivated researchers to develop MEMS based energy harvesters. Recently, the use of AlN as a piezoelectric material has increased fabrication compatibility, enabling the realization of smart integrated systems on chip which include sensors, actuators and energy storage. Piezoelectric MEMS energy microgenerator is used to capture and transform the available ambient mechanical vibrations into usable electric energy via resonant coupling in the thin film piezoelectric material. Analysis and modeling of piezoelectric energy generators are very important aspects for improved performance. Aluminum nitride as the piezoelectric material is sandwiched between two electrodes. The device design includes a silicon cantilever on which the AlN film is deposited and which features a seismic mass at the end of the cantilever. Beam theory and lumped modeling with circuit elements are applied for modeling and analysis of the device operation at various acceleration values. The model shows good agreement with the experimental findings, thus giving confidence in the model.

Energy harvesting for assistive and mobile applications

“…Micromachined piezoelectric energy harvesters are capable of generating electrical power up to 100 lW, which can power several microdevices for unlimited period of time [62,63]. These devices are increasingly receiving attention with respect to ambient energy harvesting, due to their small size and conversion efficiency.…”

“…These devices are increasingly receiving attention with respect to ambient energy harvesting, due to their small size and conversion efficiency. Example of working prototypes that have been developed include, harvesting of acoustic energy [64], and the harvesting of energy generated in seemingly innocuous human occupational activities such as typing on a keyboard [62,63]. For example, Wacharasindhu and Kwon [63] developed an integrated micromachined electromagnetic and piezoelectric energy harvester capable of generating a maximum power of 40.8 lW across 3 MO resistance for the piezoelectric element, and up to 11.6 pW across a 700 O for electromagnetic element.…”

Energy Harvesting from Vibrating Piezo-Electric Structures

“…This generated power from what is considered as autonomous and reliable energy source can be used to drive various sensing and actuating devices [1]. They can be for example implemented in aircraft systems, (e.g.…”

Fabrication of Aluminum Nitride Films by Reactive Pulse DC Magnetron Sputtering for Vibration Energy Harvester

“…AlN films have been used widely in a variety of sensing, actuating and transduction applications because of their excellent physical and chemical properties in recent years [1,2]. Now they are increasingly studied in energy harvester applications due to their high-energy density, moderate voltage levels, good electromechanical coupling coefficients, low permittivity especially their compatibility with CMOS processes as opposed to other piezoelectric ceramics such as lead zirconate titanate (PZT) and polycrystalline zinc oxide (ZnO) [3][4][5]. AlN films have been deposited in several methods including molecular beam epitaxy (MBE) [6,7], chemical vapor deposition(CVD) [8,9] and reactive magnetron sputtering(RMS) [10][11][12][13].…”