MICROMACHINED SENSOR STRUCTURES WITH LINEAR CAPACITIVE RESPONSE

Capacitive membrane-type pressure sensors normally have nonlinear pressure capacitance relationships, implying the need for sophisticated electronics. Various capacitive pressure sensor structures with improved linearity are suggested in this article. These include membranes that touch the bottom of the cavity, corrugated or thinned membrane edges with stiffened membrane centers, as well as a sensor structure with a double-comb design. The design possibilities increase with these methods. Most work was carried out with the help of finite element analysis (FEA). Pressure sensors have been manufactured based on the FEA simulations, and the experiments verify the calculations. The results show very promising linearity properties, with nonlinearities less than 1%, and sensitivities around 10 pF/bar. Weaknesses introduced in the membrane can improve performance if they are located correctly.