The Structure Design Of Piezoelectric Cantilever Mass Sensor

Piezoelectric cantilever sensor is a kind of device that can transform tiny pressure into electrical signal. The piezoelectric cantilever is widely used, due to its small size, high sensitivity, portability, rapid response and high integration level.Measurement of micro mass is a very important application of piezoelectric cantilever. The piezoelectric cantilever usually works in its dynamic mode, in the measurement of micro mass test. The offset of the vibration frequency of cantilever is proportional to the additional mass. So we can get the mass by testing the change of the vibration frequency changes. It's also proved that the vibration frequency of the piezoelectric cantilever is inversely proportional to the root of effective mass, so we can improve the sensitivity of the piezoelectric cantilever for mass measurement by decreasing its effective mass. In this thesis we analyzed how the size and structure affect the piezoelectric cantilever sensitivity, and we also find a way to improve its sensitivity. The main works we did as follows:(1) The operational principle of piezoelectric cantilever is researched. The method for cantilever structure design is analyzed. We also proposed the assessment criteria of piezoelectric cantilever, working styles of piezoelectric cantilever, development of piezoelectric cantilever and vibration of piezoelectric cantilever in both air and liquid.(2) Piezoelectric effect and piezoelectric material are summarized. The methods for the connection between piezoelectric materials and the methods for the detection of piezoelectric cantilever are also proposed.(3) The structure of piezoelectric cantilever is optimized in this thesis. Based on the optimization to the structure and the ratio between the extension part and non-extension part of piezoelectric cantilever we proposed the structure configuration which can increase the sensitivity of the sensor.(4) We did an experimental validation for the optimized cantilever. Testing the structure with different size parameters and different configurations we analyzed the effect from these two factors. It's showed that the optimized structure exhibits a higher sensitivity, which is increased to 150% compared with the other structures with same size.