Structural analysis of piezoelectric cantilever transducer for in-situ characteristic measurement of polymer gel

摘要

Our previous study has proved that piezo-cantilever coated with temperature-responsive polymer gel can measure swelling ratio of the polymer in solution by piezo-impedance measuring technology. However, the sensitivity and accuracy of the piezo-cantilever transducer is related to the vibration modes actuated by the piezoelectric cell. The bending mode seems not available to work in solution as its amplitude is attenuated greatly and causes noise easily in solution. In this study, the longitudinal mode of piezo-cantilever transducer has been studied to detect physical changing due to the temperature-sensitive polymer gel. The impedance responses to variation of physical properties such as length, thickness and density of the polymer gel have been investigated. The results show that for a certain longitudinal mode, variation of length of the polymer can be neglected. The swelling ratio of the piezo-cantilever transducer is obtained theoretically. Finally. A new type of piezo-cantilever transducer is proposed that is more convenient in practice.