MEMS Generator of Power Harvesting by Vibrations Using Piezoelectric Cantilever Beam with Interdigitated Electrode
Date Issued
2006
Date
2006
Author(s)
He, Jyun-Jang
DOI
zh-TW
Abstract
近年來，由於生物醫學領域的蓬勃發展，再研究上經常需要大量且正確的統計資料，做出正確的分析。因而對於長時間監測方面的要求也同時大量增加並且在使用條件上也趨於嚴苛，直接地推動了無線感測網路架構的發展，也為臨床實驗監控或慢性病看護提供在時間與空間均無限制的可能，因此大大降低了監測的成本與難度，同時也大幅改善了病人日常生活的品質；成功地擺脫過去監測必須定點定時的不便利性。然而目前無線感測網路系統所面臨最大的瓶頸是，該如何提供足夠的能量，達成驅動感測器動作與傳輸後端網路資料回處理中心。在過去傳統有線的監測環境下，只要將儀器的電源線接上插座，再將感測子接線回儀器，就可以達成觀察看護的目的。相對於無線感測網路，則在能源供給這方面，被迫必須另尋他法得到能量；最簡單的解決方式，是以電池（碳鋅或鋰電池）來供給所需能量；不過，使用電池提供能源卻存在有先天的限制以及缺點，就是電池使用壽命的問題。因此，容許能夠使用電池的操作環境，勢必是容易將電力耗盡的舊電池更換成新電池的狀況，同時也限制了以電池供能的適用範圍。為了解決這個問題，出現了幾種新的能量供給概念，如太陽能，力－靜電能。其中一種替代方法，是利用壓電材料的特性，產生足以供給感測網路需要的能量。以物理的觀點，壓電材料本身可視為一種換能器，可以將外界所施加在材料上的應力或應變（屬於機械能）輸入，轉變成為電壓或電位移（屬於電能）輸出，藉由此機械－電的能量轉換特性，使得具有特殊外型的壓電材料結構可由外在環境的震動中擷取出能量，再轉換成為可供給感測器網路使用的電能。
Over the years, there has been a growing interest in the field of power harvesting technologies for low-power electronic devices such as wireless sensor networks and biomedical sensor applications. Of all possible energy sources, the mechanical vibrations have been considered a potential choice for power harvesting in a wide variety of applications. This paper presents the development of a piezoelectric MEMS generator which has the ability to scavenge mechanical energy of ambient vibrations from their surroundings and transform it into electrical energy that can be used in energy storage applications. The piezoelectric MEMS generator comprises a beam structure based on the silicon wafer, which has interdigitate electrode placed in between the lead zirconate titanate (Pb(Zr,Ti)O3, PZT) material and the beam structure, to transform mechanical strain energy into electrical charge by using the d33 mode of PZT. An optional proof mass can be built at the tip of the beam so as to adjust the structure resonant frequency of the piezoelectric MEMS generator in order to match the ambient vibrations. A theoretical model was also presented to investigate the relations between the charge generation ability and the design parameters of the piezoelectric MEMS generator.
Subjects
壓電材料
換能器
震動取能
應力
電位移
piezoelectric material
generator
vibrations
PZT
mechanical energy
Type
thesis
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