A load cell or force sensor is a device that converts force or load into an electrical signal; a set of digital bathroom scales probably uses at least one load cell. There are many different types of load sensors, but ours are strain gauge load cells. The load cell itself is a mechanical structure designed so that part of it deforms linearly proportional to the force or load applied. This part of the load cell is fitted with strain gauges. A strain gauge is a resistive device that changes its resistance when it is stretched; this converts the physical parameter (the mechanical extension of the load cell) into an electrical signal.

Load cells are used in any application where you need to measure a load or force. Everything from weighing a truck (on a weighbridge) to measuring the force required to insert one component into another. Load cells (or force sensors) are very often used in conjunction with LVDT displacement transducers so that the characteristics of a test object can be measured (i.e. how far it extends for a given force).