Stiffness Measurement of Micro-Cantilever Based on Negative Electrostatic Stiffness

Micro-cantilever is basic structure of Micro-Electro-Mechanical-Systems (MEMS) sensor, and mechanical stiffness is the most important parameter of micro-cantilever. The mechanical stiffness can be affected by shape, size and material, and it should be experimentally measured for fabrication variation. Yet, the micro scale of MEMS cantilever makes the measurement difficult, and the traditional method isn't suitable for the micro-cantilever. This study proposes a new method for measuring the mechanical stiffness of micro-cantilever, and measurement of MEMS accelerometer was also experimentally carried out. The proposed method exploits the feature that the voltage applied on cantilever can lead to negative electrostatic stiffness, and this stiffness can change the deformation of cantilever. The mechanical stiffness can be obtained through analyzing the change of output. Results from this study coincided with our theoretical model, and the difference between results obtained by this method and SEM was 2.2%. This work provides a new way to precisely obtain mechanical stiffness of micro-cantilever using non-destructive method, making it helpful for researchers to design micro-cantilever and MEMS devices.