螺旋型壓電微型能量擷取器之設計及研製

Design and Fabrication of PZT MEMS energy harvesting device with spiral cantilever beam

王健宸(Chien-Chen Wang)

指導教授 ： 林致廷

共同指導教授 ： 吳文中

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01449

摘要

隨著物聯網時代的來臨，將會有越來越多的智慧元件安裝在環境周遭，其中所需的大量能量來源，即成為眾人探討的議題，進而帶動能量擷取系統的發展，幸虧近年來VLSI製程的進步，電子產品不斷微型化且耗電量降至微瓦(micro-Watt)等級。在體積小，且所需耗能低的情形下，能量擷取裝置成為傳統電池的替代方案之一，研究顯示日常環境中的振動頻率約為200 Hz以下，且並非為固定頻率之弦波振盪，因此若能有效地降低元件之共振頻率並且運用非線性振動子之理念使其壓電能量擷取系統提升其頻寬為本研究之研究標的。
本論文呈現使用微機電製程製作壓電微型能量擷取器，可將環境之振動能轉換成電能輸出，為了能有效的轉換環境中的振動，本論文設計了d31模式的螺旋型壓電微型能量擷取器並且設定元件的共振頻為20 Hz至60 Hz之間，並使用不鏽鋼薄板作為基板，使元件能承受高加速度之振動環境，進而增加元件耐用程度及實用性；沉積壓電層部分使用實驗室自製之氣膠沉積系統。另外為了增加能量擷取器的頻寬，本研究使用在系統中加入磁場的方式使微型能量擷取器操作在非線性下以有效的增加元件的操作頻寬。
實驗結果顯示，以不鏽鋼作為基板的螺旋型壓電式能量擷取器，其共振頻為51 Hz，且在0.1 g底下有輸出電壓為2.4 V而輸出功率為22uW，且最佳負載阻抗為330 k ohm，在0.65 g底下有輸出電壓5.1 V，輸出能量為10 uW。並且在非線性研究方面，研究結果在加入2.0 cm磁場的環境下，在0.15 g、0.20 g、0.25 g、0.30 g的加速度底下，頻寬會有179 %、144 %、199 %、91 %的頻寬改變；在加入1.6 cm磁場的環境下，在0.15 g、0.20 g、0.25 g、0.30 g的加速度底下頻寬會有420 %，198 %、226 %、111 %的改變。加入磁場後，磁力產生的非線性效應對於元件操作頻寬有明顯的變寬。
關鍵字：微機電、壓電材料、能量擷取、壓電式發電、非線性

關鍵字

微機電 ； 壓電材料 ； 能量擷取 ； 壓電式發電 ； 非線性

並列摘要

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.

並列關鍵字

MEMS ； Piezoelectric ； Energy harvesting ； Nonlinear

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