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The defense date of the thesis is 2016-01-26
The current date is 2019-05-22
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URN etd-0125116-171930 Statistics This thesis had been viewed 641 times. Download 0 times. Author Tzu-Sheng Hsieh Author's Email Address No Public. Department Mechanical Engineering Year 2015 Semester 1 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 49 Title Study on LiNbO3 Lateral Field Excited Humidity Sensors Keyword zinc oxide nanowire bulk acoustic wave sensor humidity sensor Lithium Niobate lateral field excited lateral field excited Lithium Niobate humidity sensor bulk acoustic wave sensor zinc oxide nanowire Abstract This thesis aims at developing a low-cost and high-sensitivity humidity sensor module which could work at room temperature by combining a Lithium Niobate (LiNbO3) lateral field excited sensor with ZnO nanowire sensing film. First of all, bulk waves in LiNbO3 are calculated using Christoffel equation for the determinations of cut angle and electric field direction. Besides, the vibration mode and frequency response of the LiNbO3 lateral field excited acoustic wave sensor are calculated through finite element analysis for the confirmation of cut angle and electric field direction. A dual delay line configuration is constructed for suppressing the interference from environmental factors. Then, the ZnO nanowires as humidity sensing film are prepared by hydrothermal method and spin coated on the 128°YX LiNbO3 wafer as the humidity sensing layer, and characterized using an X-ray diffraction (XRD) apparatus, scanning electron microscope (SEM).
In the humidity sensing experiment, the LFE sensor is tested by passing the dry air and water into the chamber for evaluation of its sensitivity and repeatability. The result shows that in three testing cycles, the frequency shifts are all about 538.3 Hz when the change in the relative humidity is 66.5%. By changing relative humidity, the sensitivity of the LFE sensor to relative humidity is measured and shows a value of 11.74 Hz/%. In conclusion, the LFE humidity sensor developed in this study is successfully measured at room temperature, and shows great sensitivity, stability and repeatability.
Advisor Committee Yung-Yu chen - advisor
Chen-Wei Liu - co-chair
Shih-Yung Pao - co-chair
Files Date of Defense 2016-01-08 Date of Submission 2016-01-26