We have load cell with three wires (black, red, blue) coming out of it. It looks there’s a strain gauge between each pair of wires:
black —/\/\/\— red: ~1kohm
blue —–/\/\/\— red: ~1kohm
black—-/\/\/\—blue: ~2 kohm
Moreover, the resistances change when we compress the load cell. In the following photographs, you can see a circular load cell, and it gets covered with a blue clamp – which is what I am using to exert a force.
It looks like the resistance of the black–red gauge increases on compression, but the blue—red’s decreases. Similarly, if we put both these resistors / strain gauges in series, and put 5 volts across them, we find the voltage drop across one to increase, and the other to decrease, when we apply compression!