溫濕度同步量測之複合式表面聲波無線感測器

無論是基於人體舒適的考量，或是在醫療、化學、農業等許多領域中環境的控管，相對濕度及溫度的控制一直具有龐大的需求。將感測器結合無線傳輸能力可提供量測的便利性，並降低監測系統成本。傳統上一般感測器如欲達成無線量測的要求，必須將其與無線射頻模組結合，導致感測器成本提高、使用壽命更受制於電池。為了減少成本並增加感測器壽命，具備同步溫度及濕度量測功能之被動式無線感測器便因應而生。在本論文中，藉由整合中心頻率為433MHz、128˚ YX-LiNbO3為基底之表面聲波式標籤、熱敏電阻和電阻式濕度感測器，阻抗加載型複合式表面聲波感測器已成功實現。此一感測器架構提供了許多引人注目的優點，例如：無線感測，被動式運作，以及尺寸縮小等。本文首先利用耦合模型理論來設計表面聲波式標籤之參數，並預測其頻率響應。接著，由於以樟腦磺酸為掺雜物之聚苯胺奈米纖維合成容易，同時在室溫下具有穩定表現，此聚苯胺奈米纖維便應用於濕度感測層以提高電阻式濕度感測器之靈敏度表現。最後，將製作之阻抗加載型複合式表面聲波感測器置之於實驗量測腔體中，並以不同的相對溼度及溫度環境來檢驗探討感測器的響應。實驗結果顯示，在不同的溫濕度環境下，感測器皆具有良好的線性度及靈敏度。

關鍵字

表面聲波；無線；被動式；阻抗；相對濕度；聚苯胺；奈米纖維

並列摘要

The control of relative humidity (RH) and ambient temperature is required for a broad spectrum of human comfort, medical instrument, chemical industry, agriculture, and etc. To reduce cost and increase lifetime, a passively wireless sensor which is capable of measuring relative humidity and ambient temperature should be developed to meet this demand. In this thesis, an impedance loaded SAW hybrid sensor is successfully accomplished by integrating a 433MHz 128˚ YX-LiNbO3 based SAW tag with external sensors such as thermistor and resistive RH sensor. The combination exhibits attractive advantages, such as wireless sensing, passive operation, and size minimization. First, the coupling-of-modes model was employed to design the SAW tag and predict its frequency response. To enhance the sensitivity of the resistive RH sensor, CSA-doped polyaniline nanofibers were utilized as sensitive film due to its easy synthesis and stable performance. Finally, the hybrid sensor was constructed and measured to evaluate performances. The results indicate our SAW hybrid sensor exhibits good linearity and high sensitivity.

並列關鍵字

Surface acoustic wave ； Wireless ； Passive ； Impedance ； Relative humidity ； Polyaniline ； Nanofiber

參考文獻

1. Tsuneharu Nitta, Jiro Terada, and Fumio Fukushima. “Multifunctional Ceramic Sensors: Humidity-Gas Sensor and Temperature-Humidity Sensor, ” IEEE Transactions on Electron Devices, pp. 95-101 (1982)

2. Sung-Pil Lee, Jung-Yup Cha, Yeo-Kyung Yoon, and Seong-Jeen Kim. “FET HUMIDITY SENSORS BASED ON TITANIUM OXIDE FILM,” Proceedings of the 5th International Conference on Properties and Applications of Dielectric Materials, pp. 1066-1069 (1997)

3. Masanobu Matsuguch, Takaaki Kuroiwa, Tetsuya Miyagishi, Sachiko Suzuki, Tsutomu Ogura, and Yoshiro Sakai. “Stability and reliability of capacitive-type relative humidity sensors using crosslinked polyimide films,” Sensors and Actuators B, vol. 52, pp. 53-57 (1998)

4. Kyoko Yatsuzuka, Yoshio Higashiyama, and Kazutoshi Asano. “Fundamental Characteristics of Hydrophilic Polymer (Polyether Block Amide) as a Humidity Sensor,” Japanese Journal of Applied Physics, vol. 32, pp. 461-463 (1993)

6. Marshall Brain. “How Thermometers Work,” http://home.howstuffworks.com

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溫濕度同步量測之複合式表面聲波無線感測器

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