# Development of a Cantilever-Type Electrostatic Energy Harvester and Its Charging Characteristics on a Highway Viaduct

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## Abstract

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## 1. Introduction

## 2. Device Modeling and Design Parameters

## 3. Fabrication of the Vibration Energy Harvester

## 4. Device Performance as a Vibration Power Generator

## 5. Charging Experiment by an Existing Environmental Vibration

## 6. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) A schematic model of the vibration energy harvester. Comb-drive electrodes are formed at a cantilever structure that vibrates in the out-of-plane direction; (

**b**) A side-view image of relative positions between the fixed and movable comb-drive electrodes.

**Figure 2.**Comparison of the capacitance functions. The fitting parameter ${z}_{0}$ for the Gaussian function form is chosen to be 150 $\mathsf{\mu}$m for $b=300$$\mathsf{\mu}$m.

**Figure 5.**A schematic of the measurement setup to evaluate the fabricated vibration power generator.

**Figure 6.**Measurement results of the short-circuit current and the vibration velocity of the cantilever as a function of external vibration frequency.

**Figure 7.**Observed vibration velocity as a function of the acceleration frequency under application of an external voltage in order to eliminate the electret potential via a protective resistance of 1 M$\Omega $. The lower graph is the magnified view at a frequency from 39 to 42 Hz.

**Figure 8.**Simultaneous measurement signals of the vibration velocity and output current. Root-mean-square (RMS) values of the velocity and current are 34.6 mm/s and 8.13 $\mathsf{\mu}$A, respectively.

**Figure 9.**Load resistance dependence of the output power obtained by 0.04 G${}_{\mathrm{RMS}}$ and 0.07 G${}_{\mathrm{RMS}}$ external accelerations.

**Figure 10.**Measurement results of the output power as a function of external vibration acceleration.

**Figure 11.**(

**a**) Measured time-evolution acceleration wave taken on the viaduct of a highway; and (

**b**) its power spectrum.

**Figure 12.**Charging voltage increment to the 44 $\mathsf{\mu}$F capacitance obtained by the acceleration of the viaduct of a highway.

**Figure 13.**Voltage built up in a 44 $\mathsf{\mu}$F capacitor charged by the developed energy harvester driven by the highway viaduct vibrations.

Parameters | Value | Unite |
---|---|---|

Spring constant, ${k}_{z}$ | 1200 | N/m |

Number of comb electrode pairs, n | 1283 | – |

Comb electrode length, ${l}_{comb}$ | 650 | $\mathsf{\mu}$m |

Comb electrode width, w | 30 | $\mathsf{\mu}$m |

Comb electrode thickness, b | 300 | $\mathsf{\mu}$m |

Comb electrode overlap, ${X}_{0}$ | 600 | $\mathsf{\mu}$m |

Comb electrode gap, d | 14 | $\mathsf{\mu}$m |

Cantilever thickness, h | 100 | $\mathsf{\mu}$m |

Cantilever length, ${l}_{cant}$ | 8.82 | mm |

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Koga, H.; Mitsuya, H.; Honma, H.; Fujita, H.; Toshiyoshi, H.; Hashiguchi, G.
Development of a Cantilever-Type Electrostatic Energy Harvester and Its Charging Characteristics on a Highway Viaduct. *Micromachines* **2017**, *8*, 293.
https://doi.org/10.3390/mi8100293

**AMA Style**

Koga H, Mitsuya H, Honma H, Fujita H, Toshiyoshi H, Hashiguchi G.
Development of a Cantilever-Type Electrostatic Energy Harvester and Its Charging Characteristics on a Highway Viaduct. *Micromachines*. 2017; 8(10):293.
https://doi.org/10.3390/mi8100293

**Chicago/Turabian Style**

Koga, Hideaki, Hiroyuki Mitsuya, Hiroaki Honma, Hiroyuki Fujita, Hiroshi Toshiyoshi, and Gen Hashiguchi.
2017. "Development of a Cantilever-Type Electrostatic Energy Harvester and Its Charging Characteristics on a Highway Viaduct" *Micromachines* 8, no. 10: 293.
https://doi.org/10.3390/mi8100293