What Are Load Cells & How Do They Work?

What are load cells?

Load cells are sensors or transducers found at the heart of every weighing machine, electronic scale, or piece of weighing equipment. Even your old bathroom scale! It’s here that they’re used to convert load - or force - into a measurable electrical Mv output signal.

Put simply? They’re used to measure weight.

Their precision and accuracy makes them a crucial component across a range of industries and weighing applications. Manufacturing and sorting systems, for example, rely on their precision to ensure accurate weighing of anything from bottles to cans, while they’re also hidden in plain sight in everyday items such as food & labeling scales at the deli or bench scales found at the local post office. 

How do load cells work?

A load cell produces a measurable electrical Mv output signal, but whether this is a voltage change, current change, or frequency change signal is largely dependant on the type of load cell being used and the requirements of the weighing task at hand.

These various signals allow for the easy, efficient weighing of goods in a variety of applications, often found attached to support beams, structural bearings, or underneath objects needing to be weighed via pressure or stresses such as tanks and hoppers, all the way through to bulk material management and mechanical scale conversions.

Load cells are available in a variety of different shapes and sizes. Of these, there are two overarching varieties that both use different methods to arrive at their measurements. These are:

Resistive

Resistive load cells are some of the most commonly available. These load cells operate on the piezoresistive principle - that is, a change of resistance in response to a load or strain - to create their millivolt range DC voltage output.

Capacitive

Capacitive load cells, meanwhile, are founded on the principle of a change in capacitance whenever a force is applied. This force is measured by the system’s ability to store a charge, which changes depending on the distance between the two internal plates.