Gauge factor

Gauge factor (GF) or strain factor of a strain gauge is the ratio of relative change in electrical resistance to the mechanical strain ε, which is the relative change in length.

$GF = \frac{\frac{\Delta R}{R}}{\varepsilon} = \frac{\frac{\Delta\rho}{\rho}}{\varepsilon} %2B 1 %2B 2\nu$

In practice, the resistance is also dependent on temperature. The total effect is

$\frac{\Delta R}{R} = GF \varepsilon %2B \alpha \theta$

Where

For many materials there is no change in resistivity ( $\Delta\rho=0$ ), for these materiels the gauge factor is simply

$GF = 1 %2B 2\nu$

General examples of Gauge Factor values: