以單相單向換能器設計表面聲波一氧化氮感測器

Surface Acoustic Wave Nitric Oxide Sensors Designed with Single-Phase Unidirectional Transducers

楊閔文(Ming-Wen Yang)

指導教授 ： 沈季燕

義守大學/電機資訊學院/電機工程學系/碩士(2019年)

摘要

目前，呼吸疾病可使用醫療儀器系統來進行檢測，不僅耗時且程序複雜。表面聲波元件具有體積小、靈敏性佳、複製性高以及可靠度好等優點，是一種探測微小質量變化非常有效的技術。因此，本論文設計單相單向換能器(Single-Phase Unidirectional Transducer, SPUDT)表面聲波(Surface Acoustic Wave)元件為感測器，並以Cu2+/PANI/WO3複合薄膜為感測膜，來探討其偵測微量一氧化氮的感測特性。本論文量測表面聲波感測器之振盪頻率來分析氣體感測特性，包含靈敏度、回復性、線性度、穩定性等。本論文採用SPUDT結構加上電極寬度控制(Electrode Width Control, EWC)所設計的表面聲波元件，相較於典型基本結構的表面聲波元件，能夠束縛較多表面聲波能量予以傳遞，有效地增加偵測氣體的靈敏性，當偵測50 ppb 一氧化氮時，頻率響應量增加約4倍。而在響應時間及回復時間上，EWC/SPUDT結構的感測器及典型基本換能器結構的感測器，展現結果無太大的不同。實驗結果證明本論文研製的EWC/SPUDT表面聲波感測器可於室溫下靈敏檢測ppb濃度的一氧化氮。

關鍵字

表面聲波 ； 單相單向換能器 ； 電極寬度控制 ； 梳型結構

並列摘要

Current medical instruments used for the detection of respiratory diseases are time-consuming and feature complex operation processes. Surface acoustic wave (SAW) devices have advantages including compact size, good sensitivity, and high reproducibility and reliability, so it is a highly effective technique for detecting miniature mass variation. Therefore, this study designed single-phase unidirectional transducer (SPUDT) SAW devices as the sensor, using the Cu2+/PANI/WO3 composite film as the sensor film, to investigate the sensing properties for detecting trace amounts of nitric oxide. This study measured the vibration frequency of the SAW sensor to analyze the gas sensing characteristics including sensitivity, reversibility, linearity, and stability. The SPUDT structure was combined with electrode width control to design SAW devices. The designed devices bound more SAW energy for transmission compared with SAW devices in typical structures, thereby effectively increasing the gas sensing sensitivity. When 50-ppb nitric oxide was detected, the frequency response of the EWC/SPUDT-based sensor increased by approximately four times. Regarding response time and reverse time, the EWC/SPUDT-based sensor exhibited no significant difference in comparison with sensors based on a typical transducer structure. The experimental results revealed that the designed EWC/SPUDT SAW sensor can be used to sensitively detect nitric oxide in the ppb level at room temperature.

並列關鍵字

surface acoustic wave ； single-phase unilateral transducer ； electrode width control ； comb-like structure

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