On the elastic strain coefficients of the resistance of metals

The relation between the elastic strain sensitivity coefficient of resistance and the hydrostatic pressure coefficient of resistance is not simple, owing to the tensor nature of the resistivity of solids. We discuss this relation and derive a rigorous expression which demonstrates that both coefficients have to be measured in order to characterize a given material. Simple relations which often appear in the literature should be dealt with cautiously because they usually treat the resistivity of metals as a scalar, thus eliminating one of the piezoresistance coefficients.