交流靜電式微型振動發電機之分析、設計與製作

Abstract

微機電系統是一個結合多重領域的科技平台，因此可應用的層面相當廣泛。而在無線感測網路等應用中，這些高整合性的可攜式元件都具有獨立電源的需求，加上近年來低功率互補式金氧半半導體超大型積體電路 (CMOS Very Large Scale Integrated circuit)技術的發展，積體電路的能量需求已經降低至數十微瓦 (□W)的程度，更促使了無線感測器網路跟個人健康監測應用的發展。因此，利用環境中之能源轉換為電能來供給這些可攜式元件已成為一個可行的方法。 本論文呈現一交流式振動至電能轉換器之設計、分析與製作。於1 cm2的元件面積以及9 V之輔助電源限制下，並利用先前研究所提出面積比之概念，使用Matlab/Simulink模擬及最佳化不同面積比的條件下，元件可產生之最大輸出功率。元件於有外加質量塊及面積比Sr = 0.5的條件下，可擷取10.6 □W之最大輸出功率，而於無外加質量塊及面積比Sr = 0.003的條件下，可擷取92.61 nW之最大輸出功率。另外，當面積比很大的條件下 (Sr > 0.5)，系統可簡化為簡易之戴維寧電路進行分析，透過電容之變化量來求得該元件之最大輸出功率。 本元件利用深矽蝕刻技術製作於SOI晶圓上。而製作完成之元件使用微機電運動分析儀 (MEMS motion analyzer，MMA)測量元件之機械特性，由於彈簧結構的損壞，因此未放置質量塊於元件上避免損壞，並且導致結構於振動中無法得到一穩定之振動。在電性之量測中，已透過可變電容之充放電時間來求得元件可變電容以及寄生電阻之測量。

Micro-Electro-Mechanical System (MEMS) is the technology platform that integrates various fields. Due to the low power CMOS VLSI technology, the power consumption is reduced to about a few tens of microwatts to enable the development of applications such as wireless sensor networks or personal health monitoring. Therefore, it becomes feasible to power portable devices by scavenging the ambient energy. In this thesis, the design, modeling and fabrication of an AC capacitive vibration-to-electric energy converter are introduced. With the device area constraint of 1 cm2 and an auxiliary battery supply of 9 V, the device was simulated and optimized by Matlab/Simulink. The device with a 4-gm tungsten ball and area ratio of 0.5 can provide a maximum average output power of 10.6 □W. Without the external mass and with the area ratio of 0.003, the device can produce a maximum average output power of 92.61 nW. In addition, the system can be simplified to a Thevenin’s circuit at large area ratio (Sr > 0.5). The maximum output power can be calculated from change of variable capacitance. The device was fabricated in SOI wafers with deep silicon etching technology. The mechanical characteristics of the device was measurement by MMA. The reason for unstable vibration was due to the damage of springs. In the electro measurement, the parasitic resistance and variable capacitance were measured by time constant of discharge.