Research On Sensitivity Of Piezoelectric Microcantilever Sensor For Ultra-small Mass Detection

Based on electromechanical coupling effects, the sensitivity of micro-cantilever is research by analog simulation and experiments. Piezoelectric micro-cantilever sensor as new-type sensing element with high sensitivity, Piezoelectric micro-cantilever sensors with many advantages such as small volume, low cost, simple structure, fast response, high sensitivity and easily integrated etc, have been extensively applied to electronic devices, biology, chemistry, environmental monitoring and many other fields. Especially, the detection of gas and liquid ingredients, has been becoming the hot field in the domestic and foreign sensor world, by the use of dynamic mode testing method with high sensitivity owing to frequency shift caused by absorbing gas or liquid molecule, further expanding the new space for research of biochemical ultra-mass detection.Based on piezoelectric micro-cantilevers as the research objects in this thesis, the theoretical analysis and simulation of the ultra-mass micro-cantilever sensors are done.Firstly, the basic theories of piezoelectric effects are concisely introduced in this paper, and Piezoelectric bilateral coupled effect is recited. Based on the vibration theoretical model of micro-cantilever in air and in liquid, the theoretical analysis is focused on the relation between the resonance frequency and structural parameters of itself, the relation between cantilever sensitivity and resonance frequency shift, the mass of detected matter and quality factor.Based on electromechanical coupling effects of piezoelectric sensor, static analysis, modal analysis and harmonic response analysis of the piezoelectric micro-cantilever are done using finite element numerical simulation method. The effect of length, width, and resonance mode on the mass detection sensitivity of the piezoelectric cantilever has been studied systematically. According to the research work of our group on OPCM piezoelectric material, vertical vibration OPCM spring model is further put forward and numerical simulation result shows that OPCM has higher sensitivity than PZT cantilever. Frequency -amplitude curves of the cantilever in air and in liquid are obtained using finite element numerical simulation method, and the quality factor of the cantilever is compared. When the micro-cantilever works in the liquid condition, the quality factor decreases because of the effect of the liquid damping, in addition, the sensitivity will decrease with the decrease of quality factor. However, if quality factor is too high, then the stability of the micro-cantilever will decrease accordingly.Piezoelectric micro-cantilever sensor as a new type testing approach plays an increasingly important role in the development of modern analysis instruments. This work provides theoretical basis and references for further developing high-powered and high sensitivity micro-cantilever sensors.