# Sensitivity

The sensitivity indicates the output signal in mV/V which is produced when the transducer is 100 percent loaded, i.e. loaded with its nominal (rated) force. Any zero signal will be deducted. Example: A transducer shows a zero signal of -0.1 mV/V. The sensitivity is 2 mV/V; in this case, the output signal at nominal (rated) force is 1.9 mV/V. 2 mV/V is a very common output signal for force transducers. As described above, strain gage-based force transducers require a voltage supplied by the amplifiers (excitation voltage). A sensitivity of 2 mV/V means that a force transducer produces an output signal of 2 mV at nominal (rated) force, when supplied with one volt. With 5 V excitation voltage, the corresponding output voltage will be 10 mV. A force transducer's output voltage can be calculated as follows:

With U being the output voltage, U0 the excitation voltage, C the sensitivity, F the applied force and Fnom the transducer's nominal (rated) force. This formula assumes that the zero signal is ideally zero.

The transducer's behavior is similar when the force varies, i.e., the transducer from the example is loaded with half its nominal (rated) force to get 1 mV/V at the output. With an excitation voltage of 5 V this corresponds to 5 m V.

A nominal (rated) sensitivity is specified in the technical data sheets. This sensitivity is valid for all force transducers of a type and is therefore given with a tolerance, the so-called "sensitivity tolerance". For this reason, every HBM force transducer comes with a manufacturing certificate specifying the exact sensitivity for the respective transducer.

Tip: Always adjust the amplifier as specified in the manufacturing certificate or according to an existing calibration to ensure optimal measurement accuracy. In this case, the sensitivity tolerance does not affect the error computation.

The transducer can also be ordered with so-called TEDS. A small chip containing the manufacturing certificate's exact specifications is installed in the transducer or in the cable. Amplifiers supporting this feature can read these data and use it for automatic setup.

# Force Measurement Glossary: Characteristics of Force Transducers

Benefit from our practical on-line glossary to look up the most important technical terms in the field of force measurement: