128°YX-LiNbO3基底表面聲波式溼度感測器之研究
Study of 128°YX-LiNbO3 Based Surface Acoustic Wave Humidity Sensor
Date Issued
2006
Date
2006
Author(s)
Wu, Jun-Yi
DOI
en-US
Abstract
With the development of industries, there is a growing need for sensitive, accurate, and inexpensive sensors of measuring relative humidity. Humidity sensors are expected for a broad spectrum of applications in meteorology, chemical industry, process control, medical instrument, agriculture, and etc. A good sensor should be characterized by high sensitivity, wide dynamic range, fast response, good reproducibility, easy interface electronics, small size, and minimum cost. It is hard for single sensing system matches all these criterions. However, surface acoustic wave ( SAW) sensing devices are promising candidates to pursue the above goals.
In this thesis, the 145MHz based SAW resonator is fabricated and integrated with the amplifier to form a SAW-based oscillator. To function as a humidity sensor, hygroscopic polymer polyethylenimine is coated on the delay line of the resonator as sensing film by airbrush method. Moreover, dual delay line configuration is constructed for the common mode rejection for external influences such as temperature, drift, etc. Then, the sensing devices are exposed to repeated cycles with various relative humidity to investigate the performances including sensitivity, reproducibility, and repeatability. The results reveal good linearity between frequency shifts and various relative humidity and enough short-term repeatability.
Subjects
表面聲波
共振器
溼度感測器
聚乙基亞胺
噴槍
靈敏度
Surface acoustic wave
Resonator
Humidity sensor
Polyethylenimine
Airbrush
Sensitivity
Type
thesis
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