Numerical simulation and experimental verification of the piezoresistivity phenomenon for the printed thick-film piezoresistors

Even though piezoresistivity has been applied in a number of electronic and microelectronic devices for years, it is still a challenge to achieve high consistency between experimental and numerically simulated results. The common problem connected with calculation of the strain dependent resistance is an evaluation of a total resistance value R of a resistor under pressure load. It is done most often by measuring the gauge factor GF, which refers to the piezoresistance phenomenon rather than piezoresistivity, and can be calculated by Ohm´s law, R=U/I. Unfortunately, this approach has turned out to have certain restrictions especially in reference to the numerical modelling, where instead of the piezoresistance phenomenon, the piezoresistivity material property changes due to mechanical load. The current paper refers to the anisotropic piezoresistivity material properties evaluation in the case of thick film resistors printed on alumina substrates.