Design and Fabrication of PZT MEMS energy harvesting device with spiral cantilever beam
Date Issued
2013
Date
2013
Author(s)
Wang, Chien-Chen
Abstract
With the arrival of the era of “Internet of Things”, smart components are been used everywhere in our everyday life. This surge of component usage will inevitably bring the issue of power supply, something that is necessary in high volume to support the rapid growth rate of said components. Fortunately, the recent advancements in VLSI fabrication technology have provided us opportunities to produce low energy consuming electric components, generally to the order of a few micro-Watts. Energy harvesters have since become one of the best ways to provide energy to these small sized, low energy consuming components. Studies indicate that most of the vibrational frequencies found in a regular environment are below 200 Hz and they are not a constant frequency of sinusoidal vibration. Therefore, this work focuses on lowering the resonance frequency of the energy harvester while also increasing the bandwidth via the theory of non-linear oscillator.
The MEMS fabrication energy harvester shown in this paper is capable of transforming vibrational energy from the environment into electrical energy. To efficiently convert the vibrational energy from the environment, a d31 mode of spiral-shaped piezoelectric cantilever design is used for the energy harvester. The harvester component is designed to operate under the resonant frequency of around 20Hz to 60Hz. The device utilizes a stainless-steel based substrate so that it can sustain environments with vibration levels of high acceleration. This will increase the durability and practicality of the device. To deposit the piezoelectric layer on the substrate, the Aerosol deposition system developed in our lab is used. To increase the bandwidth of the energy harvester, this work uses the application of magnetic field to operate the micro energy harvester in the non-linear region to accomplish the task.
Experimental results show that the spiral piezoelectric harvester design with stainless-steel substrate fabrication has a resonant frequency of 51 Hz. Under 0.1 g acceleration, the output voltage is 2.4 V and the output power is 2uW. with optimal load at 330 k ohm. Under 0.65 g acceleration, the output voltage is 5.1 V and the output power is 10 uW. The experimental results on non-linear performance shows that when a magnetic field with a gap of 2.0 cm is applied, under an acceleration of 0.15 g, 0.20 g, 0.25 g, and 0.30 g, the bandwidth has a change of 179 %, 144 %, 199 %, and 91 %, respectively. When a magnetic field with a gap of 1.6 cm is applied, the change of bandwidth becomes 420 %, 198 %, 226 %, and 111 % respectively for the aforementioned acceleration levels. When a magnetic field is introduced, the magnetic force’s non-linear effect to the enlargement of the device’s operational bandwidth is rather noticeable.
Subjects
微機電
壓電材料
能量擷取
壓電式發電
非線性
Type
thesis
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