Strain gauge sensors are the fundamental sensing elements for many types of sensors e.g. force sensors, torque sensors, pressure sensors, acceleration sensors, etc. They are applied to measure strain. Having strain measured and using Young’s modulus
and geometric sizes, stress can be calculated. Finally, from these calculations an unknown and investigated quantity can be found, which is applied and acts on an object under test. Strain gauge principal of operation takes advantage of the physical property of the variety of changes of electrical resistance resulting from its elongation or shortening. If a strip of conductive material is stretched, it becomes skinnier and longer resulting in an increase of its resistance
while if it is compressed, it becomes shorten and broaden resulting in decrease of its resistance. The principle of operation of a common metallic strain gauges is based on a change of a conductor resistance.