The 12 types of sensors: their characteristics and functions

Do you know what a sensor is? What is it for or how does it work? In this article, in addition to answering these questions, we will talk about 12 different types of sensors. As we will see, these vary depending on the type of variable they are measuring or detecting.

In addition, we will explain their general characteristics, what they are used for, how they work, and we will give a few examples.

What is a sensor?

Before explaining the different types of sensors that exist, we will see what a sensor is. It is surely a concept which comes to you from physics, even from chemistry. but what is it exactly?

A sensor is a device or an object that has the capacity to capture different stimuli from the outside, and to transform them with the help of a transducer into electrical energy (electrical impulse).. In other words, it transforms (or translates) information or energy from the outside into an electrical impulse (usually a digital impulse). This external information can be of any type (physical, chemical, etc.).

Subsequently, these impulses are analyzed, processed and transformed, in order to generate a given response. We can find different types of sensors, as we will see below.

Types of sensors

Thus, there are different types of sensors, depending on the type of variable they must measure or detect. In this article we told you what are the 12 types of sensors that we can find, how they work and some examples of them.

1. Temperature sensor

The temperature sensor provides us with information about the outside temperature (I.e. from the middle), by electrical impulses. These sensors allow you to monitor the ambient temperature.

Temperature sensors are actually resistors, the value increases with temperature or decreases with it. In the first case, we call it PTC thermistor, and in the second, NTC thermistor.

In turn, temperature sensors can be of different types: contact, non-contact, mechanical and electrical. An example of a temperature sensor is a thermometer (the classic one, mercury) (in this case, it is a mechanical sensor). These types of sensors are used in particular in the industrial sector; its purpose is to control the temperature of different machines, among other things.

2. Light sensors

Other types of sensors are light; in that case, they are electronic devices that respond to the change in light intensity.

In other words, they can determine the presence of light. Thus, these types of sensors detect visible light (that is, what we perceive with the eye), and also respond according to its intensity.

An example of a light sensor is the photoelectric cell, a device that converts light energy into electrical energy, through an effect called a “photoelectric effect”. This device makes it possible to generate photovoltaic solar energy.

3. Distance sensors

Distance sensors are devices that measure distances; in addition, depending on the type, they can also be used as presence or movement sensors.

An example of a distance sensor is infrared, based on a system for emitting and receiving radiation. As an example of a distance sensor, we also find the ultrasonic sensor, which sends pulses bouncing the waves off the surface.

4. Proximity sensors

The following types of sensors, those of proximity, consist of transducers that detect the presence of objects (Obstacles, people …) without the need for contact. In some cases, they can also be configured to measure distance.

5. Position sensors

Position sensors allow us to determine the location of a particular object. As a feature of these, we find that they usually have a special electronic system, so that they can determine the location with maximum accuracy.

6. Color sensors

Color sensors convert light into frequency, so that the colors of certain objects can be detected from their reflected radiation; what they do is compare these radiations with the recorded reference values.

These types of sensors emit three types of light: red, green, and blue, and they do so on the objects they seek to analyze. Finally, these devices generate an output signal (a response).

7. Humidity sensors

These types of sensors measure relative humidity as well as ambient temperature. More precisely, they act by emitting a conditioned signal, thanks to a series of integrated circuits available.

Humidity sensors pick up signals from the environment to detect these parameters (humidity and temperature). In addition, the margin of error available to them is generally very low.

On the other hand, by way of example, such sensors can be applied to detect the level of liquid in a tank; they are also used in garden irrigation systems, with the aim of determining when plants need irrigation and when they do not.

8. Speed ​​sensors

Also known as “speedometers”, speed sensors allow you to detect the speed of an object (usually a vehicle).

An example of these are speed cameras, which detect if a vehicle is traveling at a speed greater than the authorized speed.

9. Sound sensors

The following types of sensors are audible; are responsible for capturing sounds from the outside (environment), Via a microphone or sonar system.

The sound waves received by these sensors propagate through the air in the middle and are then detected by the sensors.

They are generally used to receive stimuli from the outside in the form of orders (from people), at a distance.

10. Contact sensors

Contact sensors are intended to detect the end of the path of mechanical components (or in other words, their limit position). An example of these are: the doors that open automatically, that when they are already fully open, the motor that drives them “knows” that it must stop.

11. Optical sensors

In this case, these types of sensors can detect the presence of an object (or a person) that interrupts a beam of light that reaches the sensor.

An example of them (and the main ones) are the so-called “photoresistors” (also called LDRs). LDRs are mainly used in robotics, in order to regulate the movement of robots and stop their movement when they are about to fall on another object.

12. Magnetic sensors

Magnetic sensors they work by detecting magnetic fields caused by electric currents or magnets.

An example of these types of sensors is the reed switch, which consists of two sheets of metal inserted inside a capsule; these sheets are in the presence of a magnetic field and are attracted to each other (that is, they close the circuit).

Bibliographical references:

  • Brindley, K. (1988). Sensors and transducers. Heinemann Newnes.

  • Norton, HN (1989). Transducer manual. Prentice Hall.

  • Pallás, R. (2003). Signal sensors and conditioners, Ed. Marcombo.

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