A new structure and modeling of a three-axis MEMS capacitive accelerometer with high dynamic range and sensitivity

In this paper, a three-axis capacitor accelerator has been analyzed, modeled and optimized using micro-electromechanical systems technology. In the proposed structure, acceleration measurements are carried out on all three axes simultaneously using a mass and spring system, which makes it possible to achieve a high sensitivity at a low occupancy level without losing other accelerator factors. In this structure, it is shown that each axis acceleration has a very low impact on the acceleration of the other two axes. If any external factor (e.g., electromagnetic waves) changes the value of a single capacitor, the original output of the capacitor does not change for detecting acceleration. In this paper, first the model is extracted for the proposed accelerometer structure and then to prove the validity of the model, the proposed structure is simulated using Intellisuite software. Moreover, a multi-objective genetic optimization algorithm which is made of NSGA2 and SPEA algorithms has been used to determine the dimensions of the constituents of the spring and the weight. This algorithm is implemented in MATLAB software. This study covers a dynamic range up to 1000 g and an operating frequency up to 20 kHz. The accelerometer sensitivity is 4fF/g in the z axis direction while it is 9fF/g in the x and y axes directions.