Sensor

Definition

A sensor is a device that converts a stimulus (e.g. heat, pressure or light) into a (in most cases electrical) signal that can be measured or interpreted. It is a part of an instrument or, in the context of this Wiki, an oceanographic instrument.

Overview

In an oceanographic instrument the stimulus can either interact directly with the detector (such as in a temperature, pressure or light sensor) or a stimulus is exserted by the instrument, then is modified by the property to be measured and the modified stimulus then interacts with the detector (such as in a fluorometer that sends out a light pulse (stimulus) that is transformed by chlorophyll in the water fluorescing (modification of stimulus); the transformed light (modified stimulus) then is interacting with the detector).

If the detector signal is not an electrical signal (e.g. an optical signal or the change of a property such as colour) it can be converted to an electrical signal by a transducer in the instrument.

Important properties

• Sensitivity: The smallest change in the property to be measured that leads to a measurable change in the detector signal.
• Selectivity: In how far the change of other properties than the one to be measured leads to a change in the detector signal.
• Range: The span between the extremes of the property to be measured at which no further change in detector signal occurs.
• Linearity: