Improved Performances of Acoustic Energy Harvester Fabricated Using Sol/Gel Lead Zirconate Titanate Thin Film
Energy harvesters integrable on smart sensor systems have been strongly demanded. Microelectromechanical system (MEMS) acoustic energy harvesters using the first resonance vibration of a lead zirconate titanate (PZT) thin film as a diaphragm have recently been reported. Similar acoustic energy harve...
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| Published in | Japanese Journal of Applied Physics Vol. 50; no. 6; pp. 06GM14 - 06GM14-5 |
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| Main Authors | , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.06.2011
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| Online Access | Get full text |
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| Summary: | Energy harvesters integrable on smart sensor systems have been strongly demanded. Microelectromechanical system (MEMS) acoustic energy harvesters using the first resonance vibration of a lead zirconate titanate (PZT) thin film as a diaphragm have recently been reported. Similar acoustic energy harvesters using the third resonance of a PZT diaphragm fabricated by sol/gel PZT thin film processes exhibited improved generated power density, and it was suggested that the PZT acoustic energy harvester might be suitable for use as a possible power source for silicon integrated circuits. We present further improved power generation performances of PZT MEMS acoustic energy harvesters fabricated by improved PZT capacitor fabrication processes. The PZT acoustic energy harvester with the diaphragm diameter of 1.2 mm fabricated by a sol/gel process generated an even higher energy density of 98 μW/m 2 under the sound pressure level of 100 dB (0.01 W/m 2 ) at 16.7 kHz. |
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| Bibliography: | (a) Top view and (b) crosssection of the structure of energy harvester with PZT diaphragm. (c) Third-resonance mode and (d) First-resonance mode investigated in this research. Experimental setup for measuring the resonance frequencies and the generated power. Fabrication processes of PZT energy harvesters using microfabrication techniques: (a) Pt/Ti sputtering, (b) PZT spin coating, (c) Al mask deposition, (c$'$) Al wet etching, (d) Patterning of cavity, and (e) ICP dry etching of Si. Photographs of PZT energy harvester (a) after Al top electrode definition process by wet etching and (b) after mask deposition of Al top electrode. (c) Conceptual description of PZT capacitor damage by Al wet etching. Equivalent circuit for energy harvester consisting of ac-voltage source, $E$, and internal resistance, $r$, and load resistance, $R$. Load resistance, $R$, dependence of generated power for energy harvester with diaphragm diameters of (a) 1.2 mm (Al mask deposition), (b) 2.0 mm (Al mask deposition), and (c) 2.0 mm (Al wet process). The sound pressure was 100 dB at the resonance frequencies for each device. Frequency dependences of generated voltage, $E$, of PZT energy harvester with different diaphragm diameters from 1.2 to 2.0 mm. The frequency at each allow corresponds to first resonance. Measured relationships between power delivered to load and load resistance for PZT acoustic energy harvesters with different diaphragm diameters. |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.50.06GM14 |