Challenges in fabrication and testing of piezoelectric MEMS with a particular focus on energy harvesters

Rezaei, Milad; Lueke, Jonathan; Raboud, Don; Moussa, Walied A.

doi:10.1007/s00542-012-1721-8

Cited by 13 publications

(12 citation statements)

References 135 publications

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“…[3][4][5][6][7][8] Piezoelectric vibration energy harvesters based on PZT (lead zirconate titanate) or AlN (aluminum nitride) thin film have been studied widely, [9][10][11][12][13][14] a same cantilever could increase the operation bandwidth and output power of piezoelectric energy harvesters when these PZT elements were connected in parallel, and the amplitude of the cantilever was limited. 18 Dayou et al investigated the performance of width-split piezoelectric energy harvester and found that its bandwidth can be increased by wider variation in natural frequency of each participating split beam and connecting them in parallel.…”

Section: Introductionmentioning

confidence: 99%

ZnO thin film piezoelectric MEMS vibration energy harvesters with two piezoelectric elements for higher output performance

Wang

2015

Review of Scientific Instruments

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Zinc oxide (ZnO) thin film piezoelectric microelectromechanical systems (MEMS) based vibration energy harvesters with two different designs are presented. These harvesters consist of a silicon cantilever, a silicon proof mass, and a ZnO piezoelectric layer. Design I has a large ZnO piezoelectric element and Design II has two smaller and equally sized ZnO piezoelectric elements; however, the total area of ZnO thin film in two designs is equal. The ZnO thin film is deposited by means of radio-frequency magnetron sputtering method and is characterized by means of XRD and SEM techniques. These ZnO energy harvesters are fabricated by using MEMS micromachining. The natural frequencies of the fabricated ZnO energy harvesters are simulated and tested. The test results show that these two energy harvesters with different designs have almost the same natural frequency. Then, the output performance of different ZnO energy harvesters is tested in detail. The effects of series connection and parallel connection of two ZnO elements on the load voltage and power are also analyzed. The experimental results show that the energy harvester with two ZnO piezoelectric elements in parallel connection in Design II has higher load voltage and higher load power than the fabricated energy harvesters with other designs. Its load voltage is 2.06 V under load resistance of 1 MΩ and its maximal load power is 1.25 μW under load resistance of 0.6 MΩ, when it is excited by an external vibration with frequency of 1300.1 Hz and acceleration of 10 m/s(2). By contrast, the load voltage of the energy harvester of Design I is 1.77 V under 1 MΩ resistance and its maximal load power is 0.98 μW under 0.38 MΩ load resistance when it is excited by the same vibration.

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Section: Introductionmentioning

confidence: 99%

ZnO thin film piezoelectric MEMS vibration energy harvesters with two piezoelectric elements for higher output performance

Wang

2015

Review of Scientific Instruments

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“…This both increases the volume of piezoelectric, and allows the output voltage of a given film in a bimorph structure to be approximately doubled relative to that of a unimorph without increasing the total area of the device. However, challenges are encountered in the growth of a phase‐pure PZT film at elevated temperatures due to the volatility and propensity for resputtering of PbO . Consequently, the amount of excess Pb in the PZT target, the oxygen and Ar pressure, and the substrate temperature were optimized, as described elsewhere …”

Section: Resultsmentioning

confidence: 87%

“…Although there are previous reports on highly (001) oriented, dense PZT films, most of these describe films with 0.5–4 µm thickness on Si, where the figure of merit for energy harvesting is low. In this work, a high‐temperature sputtering approach was adopted to grow thick PZT films on both sides of Ni foils.…”

Section: Introductionmentioning

confidence: 99%

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

Yeo

Xue

Roundy

et al. 2018

Adv Funct Materials

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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.

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“…Several difficulties encountered with this chosen method of releasing the energy harvester structure will be discussed at length in the following sections. Throughout the remaining microfabrication process flow, several obstacles were encountered, including difficulties caused by titanium residues from lower electrode etching, uneven and non-continuous films deposited by a simultaneous sol-gel and lift-off process, and wafer handling issues caused through the backside etching required to release the harvesters from the silicon wafer [ 9 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the harvester operates under a base vibration, wafer-level testing was not possible. Therefore, full packaging of the harvesters were required, leading to several challenges dealing with adhesion of wirebonds and the overall design and implementation of suitable packaging [ 9 , 19 ]. Finally, significant challenges were encountered in designing and fabricating suitable conditioning circuitry including maximizing the efficiency and charging current delivered to the storage medium.…”

Section: Introductionmentioning

confidence: 99%

Microfabrication and Integration of a Sol-Gel PZT Folded Spring Energy Harvester

Lueke

Badr

Lou

et al. 2015

Sensors

Self Cite

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This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel PZT film quality and adhesion issues. A packaging and integration methodology was developed to allow for the characterizing the harvesters under a base vibration. The conditioning circuitry developed allowed for a complete energy harvesting system, consisting a harvester, a voltage doubler, a voltage regulator and a NiMH battery. A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit. It was found that the maximum efficiency does not correlate to the maximum charging current supplied to the battery. The efficiency and charging current must be balanced to achieve a high output and a reasonable output current. The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

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Challenges in fabrication and testing of piezoelectric MEMS with a particular focus on energy harvesters

Cited by 13 publications

References 135 publications

ZnO thin film piezoelectric MEMS vibration energy harvesters with two piezoelectric elements for higher output performance

ZnO thin film piezoelectric MEMS vibration energy harvesters with two piezoelectric elements for higher output performance

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

Microfabrication and Integration of a Sol-Gel PZT Folded Spring Energy Harvester

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