||In this thesis, the piezoelectric material 128°YX LiNbO3 was used in sensing liquid and UV light. Liquid measurement contains experiments and simulations. In simulation, we use the finite element software COMSOL to simulate the sensitivities of different liquid concentrations. We design five different sensors to simulate the sensitivities of liquid viscosity, permittivity, and conductivity. On the experiments side, sputtering the Pseudo-LFE, QCM solid and ring-shape, LFE sensing electrode on the 128°YX LiNbO3 chips, measured with an oscillator circuit or network analyzer when contacting with different concentrations of glycerol, 2-propanol, or NaCl solution. The Pseudo-LFE sensors with ring-shape sensing electrodes show a comparable sensitivity with LFE sensors. QCM with ring-shape sensing electrodes shows a better sensitivity with QCM sensors of ring-shape. The experiments results exhibit similar trend and comparable values with the simulation. As a result, Pseudo-LFE sensors with ring-shape sensing electrodes is second only to the LFE sensor, better than that of QCM sensors, and exhibit stable oscillation in the air, can be applied to a variety of liquid and gas measurement.
In UV light sensing, the LFE sensor based on LiNbO3 substrate is fabricated and the ZnO nano-rod was grown on the sensing surface. First, we test the sensor in single oscillator and dual delay line configuration with heater to compare the interference of temperature. From the experiment result, dual in line configuration effectively reduced the frequency shift cause by temperature variation. Hence, the visible light (650 nm), UV-A light (300nm), and UV-A light (300nm) with different power density are tested. The result shows that the frequency shift of 380 nm UV-light sensing module changes when the power density increases. The sensitivity caused by UV 300 nm with power density 84.1?W/cm2 is 304 ppm. The sensitivity caused by UV 380 nm with power density 1.27mW/cm2 is 423ppm.