Topic 32. Force Sensors
The device most often used for detecting mechanical force is the strain gauge. It consists of thin metal foil etched to form a number of very fine wires. This is embedded in a plastic film.
The gauge is cemented to the object that is to be stressed. When the object is stressed there is tension on the foil which stretches the wires. They become longer and thinner (strained) so their resistance increases. The change in resistance is very small, so a special circuit is used to measure it.