Strongly (001) Oriented Bimorph PZT Film on Metal Foils Grown by rf‐Sputtering for Wrist‐Worn Piezoelectric Energy Harvesters

Abstract

For piezoelectric energy harvesters, a large volume of piezoelectric material with a high figure of merit is essential to obtain a higher power density. The work describes the growth of highly (001) oriented sputtered lead zirconate titanate (PZT) films (f ≈ 0.99) exceeding 4 µm in thickness on both sides of an Ni foil to produce a bimorph structure. These films are incorporated in novel wrist-worn energy harvesters (<16 cm 2 ) in which piezoelectric beams are plucked magnetically using an eccentric rotor with embedded magnets to implement frequency up-conversion. The resulting devices successfully convert low-frequency vibration sources (i.e., from walking, rotating the wrist, and jogging) to higher frequency vibrations of the PZT beams (100-200 Hz). Measured at resonance, six beams producing an output of 1.2 mW is achieved at 0.15 G acceleration. For magnetic plucking of a wrist-worn nonresonant device, 40-50 µW is produced during mild activity.

A Review of Piezoelectric Vibration Energy Harvesting with Magnetic Coupling Based on Different Structural Characteristics

“…The magnetic force can be used as an intermediate driving force to drive the vibration of the piezoelectric beams, which convert the vibration energy into electrical energy [ 177 , 178 , 179 , 180 , 181 , 182 , 183 , 184 , 185 , 186 , 187 , 188 , 189 ]. It is better to harvest the energy of rotational motion.…”

Performance enhancement of cantilever piezoelectric energy harvesters by sizing analysis

“…Γ ¼ P out P in (21) where P in is the energy coming from the shaker which creates the excitation. Thus, the amount of input energy can be written as [45] P in ¼ f e _ a t ð Þ…”

“…To address the issue, researchers always have been attempting to reach to higher performance using different practical methods such as modification of shape, size, material properties, and damping [11][12][13][14][15]. There were also other researchers who adopted different strategies to broaden the frequency range and improve the power output [16][17][18][19][20][21][22]. Optimization of the active electrode area in order to maximize output is another important strategy illustrated by [23][24][25].…”

Design Procedure and Experimental Verification of a Broadband Quad-Stable 2-DOF Vibration Energy Harvester

“…Among the aforementioned mechanisms, the piezoelectric material is able to convert the strain energy to electricity directly. Also, it can be easily integrated to the harvesting system especially for wearable devices and considered as flexible electronics [5,6]. Moreover, many research works were oriented toward the rectification, power management, and maximum power tracking so that the generated power can be easily used for wireless sensors [7,8,9].…”