A Design and Optimization of a New, Three-Axis MEMS Capacitive Accelerometer with High Dynamic Range and Sensitivity

In this paper a three-axis capacitor accelerator has been designed, analyzed and optimized using micro-electromechanical systems technology. The accelerometers are generally divided into three categories of single axis, two axes, and three axes in terms of their ability to measure acceleration. In the suggested 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. By taking difference in this structure, it is shown that each axis acceleration has a very low impact on the measured acceleration of the other two axes. If any external factor changes the value of a single capacitor, the original output of the capacitor does not change for detecting acceleration. In other words, the acceleration of any of these three axes, due to its designing features, does not influence the other two axes and the system performance cannot be disrupted by external factors. The other important characteristics of the accelerometers are dynamic range, operating frequency and sensitivity. This study covers a dynamic range up to 1000g 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. In this paper, the simulation of the structure is performed using Intellisuite software. Moreover, a multi-objective genetic optimization algorithm has been used to determine the dimensions of the constituents of the spring and the weight.