What is a sensor?

A sensor is a device that detects some characteristic of its environment. Sensors function as transducers, converting one form of energy into another.


eaton eac sensor

Eaton Corp EAC Series Current Sensor


Events or changes in a sensor’s environment are most commonly converted to an output voltage, a signal that can be displayed as representative of the original stimulus.

Each sensor has sensitivity, which defines how much the sensor output changes as the input quantity changes. This ratio between sensor output and measured input varies among the many different types of sensors, but linear relationships are most common. For example, a sensor that measures temperature and outputs that information as a voltage does so in a linear manner – the ratio between the two values is constant across the measurement range.


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Sensors are designed with three rules in mind: they are sensitive only to the measured property, they are insensitive to any other property that could impact the sensor’s environment, and they do not influence the measured property.

Sensors come in a huge variety of types, measuring a diverse range of stimuli using a multitude of different methods.

One example is a proximity sensor. Typically, a proximity sensor sends out a signal (an electromagnetic field or beam of radiation) and measures changes in the return signal. These devices operate over a maximum range which can be adjusted, and have a reputation for being reliable and long-lasting because there are no moving parts.


abb sif proximity sensor

ABB SIF Series Inductive Proximity Sensor


Photoelectric sensors detect the distance, presence or absence of objects by converting light information into an electrical signal. They are a form of electro-optical sensors, which measure quantities of light and translate them into readable signals and data.

These examples are just at the surface of a long list of sensors. Infrared sensors detect infrared light radiating from objects (used in motion detectors). Tactile sensors sense physical interaction like touch or pressure. Inductive sensors specifically detect the proximity of metallic objects using electromagnetic properties. Capacitive sensors use a process called capacitive coupling to detect transfer of energy between two objects through their capacitance. These sensors are common in touch screens and track pads. There are devices that detect temperature, speed, composition of the air, current and voltage, vibration, and pressure, among many other variables.

For more information on sensors, or guidance regarding how to incorporate different sensors into your application, contact Galco today!

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