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URN etd-0423112-172235 Statistics This thesis had been viewed 2009 times. Download 960 times. Author Chao-Hung Hsu Author's Email Address No Public. Department Mechanical Engineering Year 2011 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 66 Title Pseudo-LFE Acoustic Wave Sensors with Different Electrode Configurations Keyword Finite element method Pseudo-LFE piezoelectric acoustic wave sensor Frequency shift Frequency shift Pseudo-LFE piezoelectric acoustic wave sensor Finite element method Abstract Pseudo lateral field excited (Pseudo-LFE) acoustic wave sensors exhibit stable oscillation in the air due to low electric impedance. Although they are capable of detecting liquid electrical property changes, the sensitivity is not as large as lateral field excited (LFE) acoustic wave sensors. Therefore, this study modifies the sensing electrode geometry to increase sensitivity of a Pseudo-LFE sensor. At first the finite element software, COMSOL, was used to analyze the resonance modes and sensitivities of Pseudo-LFE sensors with various sensing electrode geometries to liquid viscosity, permittivity, and conductivity. Moreover, Pseudo-LFE sensors with ring-shape sensing electrodes were fabricated on AT-cut quartz and measured with an oscillator circuit or network analyzer when contacting with glycerol, 2-propanol, or NaCl solution. The simulation results exhibit similar trend and comparable values with the experiments, verifying the validity of the simulation model proposed here. Besides, Pseudo-LFE sensors with ring-shape sensing electrodes show a comparable sensitivity with LFE sensors and can measure glycerol and 2-propanol solutions of high concentration or less volume. In conclusion, Pseudo-LFE sensors with ring-shape sensing electrodes are potential in sensor applications instead of QCM (quartz crystal microbalance) and LFE sensors because of large sensitivity and wide sensing range. Advisor Committee Yung-Yu Chen - advisor
Jia-Hung Sun - co-chair
Wen-Ching Shih - co-chair
Files Date of Defense 2011-01-17 Date of Submission 2012-04-24