出平面振動式駐極體微發電機之設計、製作與量測

Abstract

由於低功率互補式金氧半半導體超大型積體電路技術發展，使得電路的功耗需求降低，促使了無線感測網路應用的發展。無線感測網路藉由分佈許多感測器來達到監視環境的情況，例如溫度、聲音、壓力、振動及汙染物等等。在工業中可應用在監測和控制、機器健康監測等，在醫學中也嘗試運用在人體中以監測人體的生理健康情形，使得醫生可在遠處掌控遠方病患的健康狀態。無線感測網路中每一個感測器消耗的功率大約為數十uW至數百uW，以溫度感測器為例，其消耗功率約為1-20uW[3]，由於所需求的功率不大，因此可從周遭環境獲取或補充能量。 在本論文中首先製作出駐極體並透過儀器來量測儲存在駐極體中的電荷量，並經由Matlab/Simulink模擬軟體建構出使用駐極體作為偏壓源的靜電電容式微發電機模型，模擬在不同的電容間距及負載電阻下所產生的輸出功率，找出產生最大輸出功率時的電容間距及負載電阻，完成元件的最佳設計，之後以此最佳化設計製作出靜電電容式微發電機，對其進行輸出功率的量測。 由於先前本實驗室所提出的微發電機，其可變電容的結構是經由蝕刻矽基板而完成，然而矽本身有易脆的特性，造成可動元件容易毀損。為了避免此問題，本論文以薄銅片及軟性電路板來製作可動結構的部份來提升結構的強健性。 本論文製作出的駐極體微發電機有兩種，其一為以銅片製作之駐極體微發電機，此元件在頻率105 Hz下，在0.25G、1G及2G的加速度下分別可產生0.147uW、、2.08uW及20.7uW的平均輸出功率。而以軟性電路板製作之駐極體微發電機則在頻率172 Hz下，加速度為2G時可產生0.82uW的平均輸出功率。

Micro-Electro-Mechanical System (MEMS) is a 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 fabrication process and measurement results of electret are presented. To design the electret power generator, the model of the electret power generator was constructed by the MATLAB/Simulink tool. The maximum output power was found by changing the initial gap of the capacitor and the output load resistor. The electret power generator was fabricated through the simulation result and the output power was measured. The previous design of our power generator is fragile due to the movable structure made of silicon. Therefore the copper and FPC board (flexible printed circuit board) were used to make a more robust movable structure. The average output power of copper-structure electret power generator is 0.147uW, 2.08uW and 20.7uW when the vibration frequency is 105Hz and the input acceleration is 0.25G, 1G and 2G, respectively. The average output power of FPC-structure electret power generator is 0.82uW when the vibration frequency is 105Hz and the input acceleration is 2G.