Sensor

A sensor detects a physical or chemical property and produces a signal representing its measurement. Its output may be electrical, optical, mechanical, or another measurable form.

Transducer: A device that converts one form of energy or signal into another. Sensors use transduction to turn changes in a measured property into output signals.
Physical quantity: A property of a physical system that can be expressed as a number and unit. A sensor is designed to respond to a particular physical quantity.
Thermocouple: A temperature sensor made from two dissimilar conductors that produce a voltage related to their temperature difference. It converts temperature differences directly into a measurable voltage.
Actuator: A device that converts a control signal into physical action or movement. An actuator acts on the world, while a sensor measures properties of it.
Signal conditioning: Processing that adjusts a signal for accurate measurement or further use. Sensor outputs often need amplification, filtering, or linearization before interpretation.
Chemical sensor: A sensor that detects chemical substances or properties through a measurable response. Chemical sensors are a major sensor class, distinct from devices measuring only physical quantities.
Strain gauge: A device whose electrical resistance changes when it is stretched or compressed. It senses deformation and enables measurement of force, pressure, or structural strain.
Detector: A device that identifies the presence or occurrence of a signal, substance, or event. A detector may report presence alone, whereas a sensor commonly represents a measured value.
Calibration: The comparison of an instrument's measurements with reference standards to establish or adjust accuracy. Calibration relates a sensor's output to known values of the property it measures.
Sensitivity (measurement): The change in an instrument's output divided by the corresponding change in its input. Sensitivity describes how strongly a sensor output responds to changes in the target property.

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