The Elasto-Resistive Effect in Metal Wires and Films

摘要

The report attempts to further a better understanding of the underlying physics of strain gauges by critically assessing a number of theoretical models suggested to explain the elasto-resistive effect in metal wires and films. By relating the phenomenological resistance variations in a metal wire to its three-dimensional stress and strain fields, the validity of the first model is tested by comparison of computed and experimentally obtained values of sensitivity to transverse strains. Secondly, sound values of longitudinal strain sensitivity are predicted from a few non-electrical physical constants by reference to a more fundamental atomic model based on the transport characteristics of electricity through bulk metals. Finally, an atomic model modified to represent metal films of widely varied thicknesses yields realistic strain sensitivities and, in particular, explains the high gauge factors observed on discontinuous metal films. (Author)