A novel approach to modeling the transfer functions of four-terminal-transducer pressure sensors within a single simulation tool

摘要

Anisotropic electrical conductivity is rarely encountered in materials of technological importance. Not surprisingly, the simulation tools required for the modeling of anisotropic conduction phenomena (such as those observed in piezoresistive transducers) are less than sophisticated. Finite Element Analysis (FEA) software packages are often limited to element types that possess orthotropic conductivity properties. We have developed a general method for the FEA of anisotropic conductivity materials that is based on the diagonalization of the conductivity matrix using main axis transformation. The new method was successfully applied to simulate piezoresistive pressure sensors with Four-Terminal-Transducers (FTTs) within a single simulation tool. The principal advantages of the new method are the fact that it does not require the user to make simplifying assumptions concerning the boundary conditions, and that it does not neglect parts of the mechanical stress tensors. In this paper, simulation results obtained using our new method are compared against simulation data from other authors and with the experimental data obtained from Motorola series MPX10 pressure sensors. Diagonalization was found to be a powerful tool for solving problems related to anisotropic conductivity in Finite Element simulation tools.