A simple analysis to improve linearity of touch mode capacitive pressure sensor by modifying shape of fixed electrode

In this paper, we simply analyze the change of touched area between the square diaphragm and the fixed bottom electrode of the touch mode capacitive pressure sensor. The virtual radius model of the circular diaphragm is utilized for the analytical analysis. A formula is derived to modify the fixed electrode shape for improvement of linearity based on the analysis. Finite element analysis (FEA) is used for simulation by software ANSYS and the accuracy of the analytical analysis is investigated. Simulation results of the proposed model show good agreement to the analytical analysis. In the model with modified electrode, the linearity is more improved than the typical one, while sensitivity is decreased. The analysis results suggest that the analytical model can be used to design fixed bottom electrode of touch mode sensor.