Each strain gauge has a diffrent sensitivity to strain, which is expressed quantitatively as the gauge factor (GF). The gauge factor is defined as the ratio of fractional change in electrical resistance to the fractional change in length (strain).
We set up a stain gauge load cell and measure that change in resistance and all is good, right? Not so fast. Strain measurements rarely involve quantities larger than a few millistrain (fancy units for strain, but still very small). So lets take an example: suppose you put a strain of 500me. A strain gauge with a gage factor of 2 will have a change in electrical resistance of only
0.12Ω is a very small change, and, for most devices, couldn’t actually be detected, let alone detected accurately. So we are going to need another device that can either accurately measure super small changes in resistance (spoiler: they are very expensive) or a device that can take that very small change in resistance and turn it into something that we can measure accurately
