可攜式氧化鋅表面聲波氣體感測器之研製

Abstract

近年來，全球石油危機逐漸浮現，引起眾多學者開始研究石油的替代能源。 水煤氣為氫氣與一氧化碳混合所產生，其在催化劑作用下生成烴類，能進一步加工生產汽油、柴油和液化石油氣等產品，減緩石油日漸減少的危機。水煤氣也是一個很好的製氫原料，與其他能源相比，氫氣是乾淨的綠色能源，但氫氣是一種極易燃燒的氣體，與空氣混合濃度在(4%~75%)範圍時，在熱、日光、火花的刺激下容易引起爆炸。一氧化碳亦為日常生活中另一種危險氣體，是由碳氫化合物燃燒不完全所產生的一種無色、無味的有毒氣體，由於其不意察覺的特性使得一氧化碳危害人體生命安全的事件層出不窮。因此製作可檢測氫氣與一氧化碳感測裝置也逐漸發展。氧化鋅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與氫氣的感測平台。 在本論文中，首先製作一組中心頻率為145 MHz且以128°YX-LiNbO3 當作基底的表面聲波振盪器，並且使用氧化鋅奈米柱結合奈米金或鉑粒子來做為一氧化碳與氫氣的感測材料。雙振盪器之量測架構用來降低諸如濕度、溫度等……環境擾動所造成的影響，此外，為了增強氣體感測的靈敏度，氧化鋅奈米柱以週期性結構方式生長於共振腔內駐波之波峰上的設計也予以呈現，實驗結果顯示，此表面聲波式一氧化碳與氫氣感測器具有良好的穩定度、靈敏度以及重複性，最後利用可編程處理器製作可攜式氫氣與一氧化碳感測器。

In recent years, the emerging of global oil crisis- has aroused the research on the finding of alternative energy . Water gas is composed of the carbon monoxide and hydrogen, it can react with catalyst to form hydrocarbons, and further processed to the gasoline, diesel oil and liquefied petroleum gas etc. Water gas is also a good hydrogen material. Compared with other energy, hydrogen is a green alternative energy, but has the drawback of its easy explosive. Any leak of hydrogen over a wide range of concentration (4%-75%) will result in explosion. The carbon monoxide is one of the most harmful pollutants which is colorless, odorless and tasteless. When human inhale the CO, it could cause symptoms of headaches, dizziness and even death. Hence, monitoring the condition of hydrogen and carbon monoxide gas is important for environmental protection and human safety. The carbon monoxide and hydrogen SAW sensor is developed for its stability, sensitivity, convenience and low cost. In this thesis, a 145 MHz SAW gas sensor based on 128°YX-LiNbO3 SAW resonators is fabricated. The ZnO nanorods and the adsorption of gold nanoparticles or platinum were adopted as the sensing material. Dual delay line configuration was employed to eliminate temperature and humidity fluctuations. In order to enhance the sensitivity of the gas detection, periodically patterned ZnO nanorods sensing film were placed at the antinodes of the standing wave. The results show that the periodically patterned ZnO possesses superior sensing response than the full area patterned ZnO. Finally, we utilized a programmable processor to integrate the the hydrogen and the carbon monoxide SAW sensors and develop a portable dual gas sensor.