A strain gauge is a long length of conductor arranged in a zigzag pattern on a membrane.
When it is stretched, its resistance increases and Vice Versa.
Strain gauges are mounted in the same direction as the strain and often in fours to form a full ‘Wheatstone Bridge’.
The animation represents what might happen if a strip of metal were fitted with four gauges.
An downward bend stretches the gauges on the top and compresses those on the bottom.
A load cell may contain several similar strain gauges elements.
Strain Gauge Animation
Credits : rdpe.com