Large-amplitude MEMS electret generator with nonlinear spring

Miki, Daigo; Honzumi, Makoto; Suzuki, Yuji; Kasagi, Nobuhide

doi:10.1109/memsys.2010.5442536

Cited by 52 publications

(37 citation statements)

References 7 publications

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“…The marginal probability density W x,st for position can be found by integrating out either momentum in (11) or velocity in (13). The result is:…”

Section: Analytical Solutionsmentioning

confidence: 99%

“…This is so either because design constraints make linear response unattainable, or because nonlinearities are believed useful in tailoring the device behaviour to the vibration of the environment. Examples of strongly nonlinear devices are found among harvesters of all the three main transducer types, i.e., electromagnetic [2][3][4], piezoelectric [5][6][7][8][9] and electrostatic [10][11][12][13][14] generators.…”

Section: Introductionmentioning

confidence: 99%

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Statistics of a noise-driven elastic inverted pendulum

Halvorsen

Litak

2015

Eur. Phys. J. Appl. Phys.

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Abstract.Recently an elastic inverted pendulum structure was proposed as a means to make nonlinear energy harvesters. An effective dynamical model of this bi-stable system has an effective lumped mass that is dependent on the displacement, hence preventing direct application of previous analyses for nonlinear harvesters driven by random vibrations. We have set up a stationary Fokker-Planck equation for the inverted pendulum and solved it to obtain explicit expressions for the stationary probability densities of the system. We found that the marginal distribution of velocity is non-Gaussian, but numerically it differs little from a Gaussian when parameters for a recently published device are used. The conditional probability of position given velocity, has two peaks for low velocities. These merge into one upon increase of velocity.

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“…The marginal probability density W x,st for position can be found by integrating out either momentum in (11) or velocity in (13). The result is:…”

Section: Analytical Solutionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Statistics of a noise-driven elastic inverted pendulum

Halvorsen

Litak

2015

Eur. Phys. J. Appl. Phys.

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“…Electret-based vibration energy harvesters (E-VEHs) can be divided into two types, in-plane [14][15][16] and out-of-plane [17][18][19][20][21], depending on the vibration direction. In-plane E-VEHs operate under vibration parallel to the electret surface, whereas out-of-plane E-VEHs do so under vibration normal to the electret surface.…”

Section: Introductionmentioning

confidence: 99%

Electret Length Optimization of Output Power for Double-End Fixed Beam Out-of-Plane Electret-Based Vibration Energy Harvesters

Gao

Liu

et al. 2017

Energies

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Thanks to miniaturization, it is now possible to imagine self-powered systems that can harvest energy from the environment to produce electrical energy. Out-of-plane electret-based vibration energy harvesters (E-EVHs) are an effective and inexpensive energy harvester type that has attracted much attention. Increasing the capacitance of variable capacitors is an effective way to improve the output power of E-EVHs. In this paper, firstly an accurate capacitance theoretical model of a double-ended fixed beam out-of-plane E-EVHs which has 97% reliability compared with FEM (COMSOL Multiphysics) results is presented. A comparison of capacitance between the double-ended fixed beam structure and a cantilever structure of the same size indicates that the double-ended fixed beam structure has greater capacitance and capacitance variation. We apply this theoretical capacitance model to the mechanical-electrical coupling model of double-ended fixed beam out-of-plane E-EVHs and study harvesters' output performances for different electret lengths by numerical and experimental method, respectively. There exists an optimal electret length to harvest maximum power in our simulation results. Enhanced electrostatic forces with increasing the electret length emphasizes the soft spring effect, which widens the half power bandwidth and lowers the resonance frequency. Increasing the length of the electret can reduce the resistance of the optimum load. The experimental results show trend consistent with the numerical predictions. The maximum output power can reach 404 µW (134.66 µW/cm 2 /g) at the electret length of 40 mm when the external acceleration and the frequency were 5 m/s 2 and 74 Hz, respectively. The maximum bandwidth reaches 2.5 Hz at the electret length of 60 mm. Therefore, the electret length should be placed between 40 mm and 60 mm, while ensuring a higher output power and also get a larger bandwidth in practical applications.

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“…Confined by the miniature size of the MEMS VEHs, the maximum displacement of the movable part is limited within the void space in the device, and the mass in the resonant structure is limited by its volume, which both limit the power of the device in low frequency. By using nonlinear soft springs, the operating frequency bandwidth is expanded at low frequencies [1], but the use of polymers in the device adds complexity to the fabrication process.…”

Section: Introductionmentioning

confidence: 99%