A batch-fabricated electret-biased wideband MEMS vibration energy harvester with frequency-up conversion behavior powering a UHF wireless sensor node

Abstract

This paper reports a batchfabricated, lowfrequency and wideband MEMS electrostatic vibration energy harvester (eVEH), which implements coronacharged vertical electrets and nonlinear elastic stoppers. A numeric model is used to perform parametric study, where we observe a wideband bimodality resulting from nonlinearity. The nonlinear stoppers improve the bandwidth and induce a frequencyup feature at low frequencies. When the eVEH works with a bias of 45 V, the power reaches a maximum value of 6.6 μW at 428 Hz and 2.0 g rms , and is above 1 μW at 50 Hz. When the frequency drops below 60 Hz, a 'frequencyup' conversion behavior is observed with peaks of power at 34 Hz and 52 Hz. The −3 dB bandwidth is more than 60% of its central frequency, both including and excluding the hysteresis introduced by the nonlinear stoppers. We also perform experiments with wideband Gaussian noise. The device is eventually tested with an RF data transmission setup, where a communication node with an internal temperature sensor is powered. Every 2 min, a data transmission at 868 MHz is performed by the sensor node supplied by the eVEH, and received at a distance of up to 15 m.

Development Trends and Perspectives of Future Sensors and MEMS/NEMS

“…MEMS energy harvesting with different conversion methods had been investigated by many researchers, which contains the piezoelectric transduction [126][127][128], the electromagnetic induction [129,130] and the electrostatic transduction [131][132][133]. When applying an external vibration onto the electrostatic energy harvester as shown in Figure 8a, the distance or area of the comb structure changed with the capacitance variation [134]. Electret material-based energy harvesting is another common topic nowadays, whereas the electricity can be generated from the capacitance variation with a pre-charged electret material as shown in Figure 8b.…”

A Novel Characterization Method for Accurate Lumped Parameter Modeling of Electret Electrostatic Vibration Energy Harvesters

“…But as η results from the dynamics of the e-VEH's mechanical part, it is harder to use the input amplitude as a control parameter on the error. Note that a technique employing the HW1 circuit has been used for electret potential measurement in [10], similar to the method presented in this paper, but using saturation voltages instead of local evolution voltages. Because of this, the method in [10] only holds if both C max and C min are fixed throughout the voltage evolution until saturation.…”

“…In particular, its accuracy relies on the assumption of uniform charge distribution across the surfaces of the transducer's facing capacitor plates. This hypothesis is not always verified, depending on both the employed charging techniques and the transducer geometry [10], [11].…”

“…Ideally, this measurement has to be done between the facing capacitor plates of the transducer. However, this is impossible to perform nondestructively on a wide range of e-VEHs because of the geometry of their transducer (e.g., interdigitated-combs [10]). More importantly, this technique gives a measure of a potential which is hard to accurately relate to the value of the electret potential.…”

Nonlinear Analysis and Performance of Electret-Based Microcantilever Energy Harvesters

“…An airflow energy harvester using flutter phenomenon and two parallel flat electret-based electrodes to convert flow-induced movements into electricity was demonstrated in [33]. A vibration-based energy harvester was fabricated using silicon and investigated in [34]. It consists of gap-closing interdigited combs on two sides of a movable mass connected to fixed ends by springs.…”