以PNVP薄膜結合表面聲波元件研製氨氣感測器之研究

Fabrication study of ammonia gas sensor by using PNVP film coated on SAW device

吳國偉(Guo-Wei Wu)

指導教授 ： 高慧玲

中原大學/電機資訊學院/電子工程研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800531

摘要

本論文敘述表面聲波(Surface Acoustic Wave, SAW)感測元件之感測機制及SAW氨氣氣體感測器之製作與量測。由實驗經驗得知溫度會對頻率產生顯著影響，為了減少溫度的影響，本論文使用42.45°切向石英(ST-Quartz)作為壓電基板，其特性在於石英壓電基板之聲速受溫度的影響甚小。並以聚乙烯吡咯烷酮(Polyvinylpyrrolidone, PNVP)薄膜材料塗佈於在表面聲波元件基板上，製作氨氣感測器並研究其感測能力。
　　完成旋塗之表面聲波元件，透過網路分析儀的量測，測得中心頻率為 194.0 MHz，插入損耗為-24.984 dB。經由電路匹配的方式，設計出表面聲波振盪器，最後再由頻譜分析儀量測測得其中心頻率為193.98 MHz。量測氨氣估算濃度從0.189%至0.756%，當聚乙烯吡咯烷酮薄膜厚度為104 nm時，獲得7.75 kHz的中心頻率差異。另外亦有對該元件不同薄膜厚度產生之差異及元件之響應時間做更進一步的分析討論。
　　實驗結果顯示聚乙烯吡咯烷酮薄膜具有一良好氨氣感測性質，能提供表面聲波氨氣感測元件應用在微量氨氣環境之感測。

關鍵字

聚乙烯吡咯烷酮 ； ST切向石英 ； 表面聲波元件 ； 氨氣感測器

並列摘要

This research describes the sensing mechanism of Surface Acoustic Wave (SAW) and the fabrication and measurement of SAW ammonia gas sensors. From experimental experience, it is known that temperature has a significant effect on frequency. In order to reduce the influence of temperature, this research uses 42.45° tangential quartz (ST-Quartz) as the piezoelectric substrate, which is known to be less temperature-affected. The polyvinylpyrrolidone (PNVP) film was coated on a SAW device to fabricate an ammonia gas sensor.
　　After the spin-coated process, the SAW device was measured by a network analyzer with a center frequency of 194.0 MHz and insertion loss of -24.984 dB. The SAW oscillator was designed by circuit simulation, and its center frequency was measured by the spectrum analyzer to be 193.98 MHz. The estimated ammonia concentration was varied from 0.189% to 0.756%. When the PNVP film thickness is about 104 nm, the center frequency shift was observed to be 7.75 kHz. The effect of film thickness on the SAW device characteristics and the response time of the gas sensor was also investigated.
　　The results show that the PNVP film has a good ammonia sensing characteristics and the combination of PNVP and SAW devices provides the potential application for wireless sensor of low concentration of ammonia gas.

並列關鍵字

PNVP ； ST-Quartz ； SAW device ； ammonia gas sensor

參考文獻

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