無線式表面聲波氣體感測器之研製

隨著科技日新月異，人們的生活環境品質以及身體健康日趨受到重視，許多有毒氣體充斥於生活環境中，其中一氧化碳即為常見的有害氣體之一，它藉由燃燒不完全所形成，並且具有無色、無味的特性，此特性常造成人們不經意將其吸入體內，輕則頭痛、暈眩，嚴重甚至死亡，對於人們健康危害甚劇。此外，一氧化碳也會對一些貴重金屬的催化劑造成毒化的現象，使其催化效果消失，如燃料電池中的白金，因此偵測一氧化碳的裝置也漸趨發展。表面聲波式之氣體感測器具有良好的穩定度、靈敏度以及低成本的特性，非常適合用來作為一氧化碳的感測平台。　　本研究中，以中心頻率433MHz、128˚YX-LiNbO3作為元件基板製作被動式無線表面聲波感測器，能直接在室溫下測量無須使用加熱器；並和天線結合製作為無須內部電源的被動式無線感測器，能與移動式燃料電池能源裝置結合架構出無線量測系統，達到即時監控之效果。具有體積小、低功耗、壽命長、無線量測且可大量製造等特性。　　首先根據表面波耦合理論來設計元件之參數，應用微機電製程技術製作表面聲波共振器及外接阻抗電極，並使用面積-體積比較高的氧化鋅奈米柱，搭配對一氧化碳有高度還原性的金粒子催化層，製作高靈敏度、製作方便、且具有重複性的感測薄膜。再使用網路分析儀擷取其頻率響應數據，使用快速傅立葉逆轉換將其轉為時域訊號，量測反射波的振幅衰減量與一氧化碳濃度的關係。最後與天線結合，達到無內部供電的被動式無線感測器，並且加大發送天線的功率，使其無線感測距離得以增加。

關鍵字

表面聲波共振器；一氧化碳感測；金-氧化鋅奈米柱；無線；被動式

並列摘要

For the sake of human safety and industry applications, the gas detection is gradually taken seriously. CO is one of the most harmful pollutants which is colorless, odorless and tasteless. When human inhale the CO, it could cause the symptoms of headaches, dizziness and even death. Furthermore, CO is able to poison the noble metals making poor performance on the catalyst like Pt used in fuel cells. Hence, monitoring the condition of hydrogen gas is important for environmental protection and human safety. The CO SAW sensor is developed for its stability, sensitivity, convenience and low cost. 　　In this thesis, the SAW resonator component was based on 128˚YX-LiNbO3 and the operating frequency was designed as 433MHz. The senor can operate at room temperature without a heater. It is available to combine the antenna with the SAW device to be a passive wireless SAW sensor. With mobile device, the sensor can link up with wireless system and monitor in real-time. 　　First, the impedance load sensor and SAW resonator were designed according to the couple of mode(COM) and fabricated by MEMS technique. For higher sensitivity and better surface-area-to-volume ratio, the zinc oxide nanorod was used to be as sensing material. Furthermore, the gold particle decorated ZnO nanorod as a catalyst for strengthening the sensitivity of carbon monoxide. Second, the signal of the impedance loaded SAW sensor was analyzed in signal processing. Finally, the wireless passive sensor was completed by combining with an antenna. Besides, the sensing distance of the passive sensor could be increased by power amplify applying background reflection.

並列關鍵字

SAW resonator ； CO sensor ； Au-ZnO nanorod ； wireless ； passive

參考文獻

[10] 黃亞珊，室溫量測之被動式表面聲波無線氫氣感測器，碩士論文，國立台灣大學應用力學研究所，台灣，2009。

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無線式表面聲波氣體感測器之研製

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