Types of sensors(theory)

Types of sensors(theory)

What are Sensors, Detectors, and Transducers?

For the purpose of determining whether a particular entity or function is present, sensors, detectors, and transducers are electrical, opto-electrical, or electronic devices made of sensitive materials or specialty electronics. There are a wide variety of sensors, detectors, and transducers available, some of which can detect physical presences like flames, metals, leaks, levels, or gases and chemicals. Some are made to detect motion or proximity, while others are made to detect physical properties like temperature, pressure, or radiation. Depending on the application, they may operate using optics or electromagnetic fields, among other things. Sensors, detectors, and transducers of a variety of kinds are used in numerous applications across numerous industries to test, measure, and control various machine functions and processes. The Internet of Things (IoT) has increased the demand for sensors as a primary tool for enhancing automation.

Top Suppliers and Manufacturers of Sensors/Detectors/Transducers

Over 500,000 industrial suppliers, manufacturers, distributors, and original equipment manufacturers can be found in a comprehensive database on’s Supplier Discovery Platform. Some of the best manufacturers of industrial sensors, detectors, and transducers are listed below for your consideration.

To access a company’s full profile, follow the link provided. This will provide you with additional, comprehensive information.

Different Types of Sensors/Detectors/Transducers

Below you’ll find a breakdown of the different types of sensors and their uses, as well as detectors and transducers.

List of Sensors

Use this list of sensors below to take you to a particular section:

Vision and Imaging Sensors

Vision and Imaging Sensors/Detectors are electronic devices that detect the presence of objects or colors within their fields of view and convert this information into a visual image for display. Key specifications include sensor type and intended application, along with any particular transducer features. More information on vision and imaging sensors may be found in our related guide All About Vision and Imaging Sensors.

Temperature Sensors

Temperature Sensors, Detectors, and Transducers are electronic devices that send signals to control and display device inputs and detect thermal parameters. Temperature is typically measured and converted into an output voltage by a thermistor or RTD in a temperature sensor. The type of sensor or detector, the maximum and minimum temperatures that can be measured, and the diameter and length are important specifications. In many process industries, temperature sensors are used to measure the thermal characteristics of gases, liquids, and solids. They can be set up for both general and special-purpose applications. Our related guide, All About Temperature Sensors, contains additional information regarding temperature sensors.

Radiation Sensors

Electronic devices known as radiation sensors or detectors detect the presence of alpha, beta, or gamma particles and send signals to counters and display devices. The type of sensor and the minimum and maximum energies that can be detected are important details. Surveys and sample counting make use of radiation detectors. Our related guide, All About Radiation Detectors, contains additional information regarding radiation sensors.

Proximity Sensors

Electronic devices called proximity sensors are used to non-contactly detect the presence of nearby objects. A proximity sensor can typically send a dc output signal to a controller when it detects objects within a range of up to several millimeters. Numerous manufacturing processes employ proximity sensors to detect the presence of machine and component parts. The dimensions of diameter and length, as well as the type of sensor, maximum sensing distance, and operating temperatures, are important specifications. Although proximity sensors typically have a short range, they can also be designed to detect objects up to several inches away. A capacitive proximity sensor is one type of proximity sensor that is frequently utilized. When the separation distance between the plates of a capacitor, one of which is attached to the object being observed, is reduced, this device uses the change in capacitance to determine the object’s motion and position from the sensor. Our related guides, All About Proximity Sensors and Capacitive Proximity Sensors, provide additional information on proximity sensors.

Pressure Sensors

Electro-mechanical pressure sensors, detectors, and transducers detect forces per unit area in gases or liquids and send signals to control and display device inputs. A pressure sensor or transducer typically detects and measures a unit area’s force with a diaphragm and strain gage bridge. Sensor function, minimum and maximum working pressures, full-scale accuracy, and any device-specific features are important specifications. When controlling or measuring a gas or liquid requires information about the pressure, pressure sensors are used. More data on pressure sensors might be tracked down in our connected aide Normal Sorts of Tension Sensors.

Position Sensors

Electronic devices known as position sensors, detectors, and transducers are used to determine the positions of various valves, doors, and throttles. and send signals to the control or display devices’ inputs. Key determinations incorporate sensor type, sensor capability, estimation reach, and highlights that are intended for the sensor type. In a myriad of control applications, position sensors are utilized wherever positional information is required. A string-pot, also known as a string potentiometer, is a type of common position transducer. Our related guide, All About Position Sensors, contains additional information regarding position sensors. See proximity sensors as well.

Photoelectric Sensors

Electrical devices called photoelectric sensors can detect objects that are within their field of detection, but they can also detect color, cleanliness, and location if necessary. An emitter and a receiver are used to measure changes in the light that these sensors emit. They are commonly used for counting, robotic picking, and automatic doors and gates in manufacturing and material handling automation.

Read our related article on photoelectric sensors for more information.

Particle Sensors

Particle Sensors and Detectors are electronic devices that send signals to control or display device inputs in order to detect dust and other airborne particles. Bin and baghouse monitoring frequently incorporate particle sensors. The type of transducer, the minimum size of particles that can be detected, the operating temperature range, the volume of the sample, and the response time are important specifications. Radiation detectors are the name given to particle detectors utilized in nuclear engineering (see above). Our related guide, All About Particle Sensors, contains additional information regarding particle sensors. See proximity sensors as well.

Motion Sensors

Electronic devices known as motion sensors, detectors, and transducers can detect the movement or stoppage of components, people, and other objects. and send signals to the control or display devices’ inputs. Typical applications of motion detection include spotting conveyor stalls and bearing seizes. The intended use, the type of sensor, the function of the sensor, and the minimum and maximum speeds are important specifications. Our related guide, All About Motion Sensors, contains additional information regarding motion sensors. See proximity sensors as well.

Metal Sensors

Metal detectors are electronic or electro-mechanical devices used to detect metal in packages, people, and other objects. Metal detectors use a variety of sensor technologies, most commonly electromagnetics, and can be permanent or portable. The intended use, maximum sensing distance, and feature choices like handheld and fixed systems are important specifications. Metal detectors can be made to specifically detect metal during particular manufacturing processes like sawmilling and injection molding. Our related guide, All About Metal Sensors and Detectors, contains additional information regarding metal sensors and detectors.

Level Sensors

Level Sensors and Detectors are electronic or electro-mechanical devices that are used to measure the height of gases, liquids, or solids in tanks or bins and send signals to control or display devices’ inputs. The typical product height is measured by ultrasonic, capacitive, vibratory, or mechanical level sensors. The sensor type, sensor function, and maximum sensing distance are important specifications. There are both contacting and non-contacting kinds of level sensors and detectors. Our related guide, All About Level Sensors, contains additional information regarding level sensors.

Leak Sensors

Electronic devices known as leak sensors or detectors are used to identify or monitor the unintentional release of gases or liquids. For instance, air leaks are detected by some leak detectors using ultrasonic technology. The soundness of pipe joints is measured by other leak detectors using straightforward foaming agents. Still, other leak detectors are used to check how well vacuum packages’ seals work. Our related guide, All About Leak Sensors, contains additional information regarding leak sensors.

Humidity Sensors

Electronic devices known as humidity sensors, detectors, and transducers measure the amount of water in the air and transform these measurements into signals that can be used as inputs for control or display devices. The maximum response time as well as the minimum and maximum operating temperatures are important specifications. More data about moistness sensors might be tracked down in our connected aide About Stickiness Sensors.

Gas and Chemical Sensors

Gas and Chemical Sensors and Detectors are electronic devices that can be fixed or mobile and are used to detect the presence of various gases or chemicals, as well as their properties, and to send signals to the inputs of controllers or visual displays. The intended application, sensor/detector type, measurement range, and features are important specifications. Constricted space monitoring, leak detection, analytical instrumentation, and other applications call for gas and chemical sensors and detectors. and are frequently designed to be capable of detecting multiple chemicals and gases. Our related guide, All About Gas and Chemical Sensors, contains additional information regarding these sensors.

Force Sensors

Electronic devices called force sensors or transducers measure a variety of forces-related parameters like weight, torque, load, and so on. what’s more, give signs to the contributions of control or show gadgets. A load cell, a piezoelectric device whose resistance changes under deforming loads, is typically the foundation of a force sensor. There are other ways to measure strain and torque. The function of the sensor, the number of axes, the minimum and maximum loads (or torques), the operating temperature, and the sensor’s dimensions are important specifications. From bolt tensioning devices to truck scales, load measuring applications employ force sensors. Our related guide, All About Force Sensors, contains additional information regarding force sensors.

Flow Sensors

Flow Sensors and Detectors are electronic or electro-mechanical devices that send signals to the inputs of control or display devices in response to the movement of gases, liquids, or solids. A flow sensor can be entirely electronic, for example, by using ultrasonic detection from outside a pipeline, or it can be partially mechanical, like a paddlewheel that sits and spins directly in the flow stream. The type of sensor or detector, the function of the sensor, the maximum flowrate, the maximum working pressure, and the minimum and maximum operating temperatures are important specifications. The processing industries make extensive use of flow sensors. Process operators can quickly be informed of flow conditions thanks to some panel mounting designs. More data about stream sensors might be found in our connected aide About Stream Sensors.

Flaw Sensors

Electronic devices called flaw sensors or detectors are used in a variety of manufacturing processes to find inconsistencies on surfaces or in the underlying materials, like welds, that are not consistent. Flaw detectors can be portable or fixed installations that use ultrasonic, acoustic, or other methods to identify defects in materials. Key particulars incorporate sensor type, perceptible deformity or thickness range, and expected application. Our related guide, All About Flaw Sensors, contains additional information regarding flaw sensors.

Flame Sensors

Optoelectronic devices called flame detectors are used to detect fire’s presence and quality and send signals to control devices’ inputs. In many combustion control applications, such as burners, a flame detector typically relies on ultraviolet or infrared detection of the presence of flame. A key detail is indicator type. Safety settings also use flame detectors, such as in under-the-hood fire suppression systems. Our related guide, All About Flame Sensors, contains additional information regarding flame sensors.

Electrical Sensors

Electrical sensors, detectors, and transducers are electronic devices that measure voltage, current, and other parameters. and send signals to the visual displays or control devices’ inputs. Hall effect detection is often used in electrical sensors, but other techniques are also used. The operating temperature range, sensor type, sensor function, and minimum and maximum measurement ranges are important specifications. Electrical sensors are utilized in everything from railway systems to fan, pump, and heater monitoring when information about the state of an electrical system is required. Our related guide, All About Electrical Sensors, contains additional information regarding electrical sensors.

Contact Sensors

Any kind of sensing device that relies on physical touch or contact between the sensor and the object being observed or monitored to detect a condition is known as a contact sensor. In alarm systems, doors, windows, and other access points are monitored by a straightforward type of contact sensor. Whenever the entryway or window is shut, an attractive change gives a sign to the caution control unit so the situation with that section point is known. Likewise, when an entryway or window is opened, the contact sensor cautions the caution regulator of the condition of that passage and may set off an activity like connecting with a perceptible alarm. Contact sensors are used in a variety of applications, including temperature monitoring and proximity sensors in robotics and automated machinery. Our related guide, “Types of Contact Sensors,” contains additional information regarding contact sensors.

Non-Contact Sensors

Non-contact sensors, in contrast to contact sensors, do not necessitate physical contact with the object being monitored in order to function. The motion detector that is utilized in security lights is a well-known illustration of this kind of sensor. Non-mechanical or non-physical methods, such as the detection of passive infrared energy, microwave energy, ultrasonic waves, and so on, are used to detect objects within a motion detector’s range. Another example of a non-contact sensor is the radar guns used by law enforcement to monitor vehicles’ speeds. Hall-effect sensors, inductive sensors, LVDTs (linear variable differential transformers), RVDTs (rotary variable differential transformers), and Eddy current sensors are just a few examples of non-contact sensors. Our related guide, “Types of Noncontact Sensors,” contains additional information regarding non-contact sensors.

Sensor Applications in Industry

A sensor is for the most part planned to create a variable sign over some estimation range rather than a switch which by and large demonstrations in a parallel style, as in on or off. Even though this isn’t always the case, it helps when choosing between switches and sensors. A level switch, for instance, can tell a pump to stop working when a certain level in a tank has been reached. However, a level sensor can provide signals that can be proportionally displayed on a readout, etc., in response to changing tank depth. A fuel tank level sensor, on the other hand, would determine the tank’s status between empty and full and send signals to a fuel gage, etc., in the same way that a sump pump might use a level switch to tell a pump to start running at a certain level. A few producers allude to this differentiation as “point” versus “consistent” detecting.

Based on what is being sensed, sensors are arranged: temperature, pressure, proximity, etc. A good place to look for specific situations in which a specifier may not be aware of the sensor/transducer type is the intended application. For instance, if a zero-speed detector requires a gear tooth sensor, choosing this option will result in a number of gear tooth detection products, some of which rely on the hall effect and others that use magnetics to detect a passing tooth. Similar outcomes can be expected if the value “zero-speed” is selected. Similarly, selecting values from the sensor/detector/transducer function will search the numerous subcategories for transducer type matches. Selecting the value “speed” will result in optical and hall effect sensors. Speed sensors can likewise be attractive or infrared-based.

The type of the transducer is another way to look for specific sensors. Choosing “infrared,” for instance, will deliver spill locators, fire identifiers, speed sensors, and so on. all of which detect using infrared light.

The subcategories share some similarities. Metal detectors, on the other hand, are available as complete units designed to detect metal on conveyor lines for food processing, injection molding lines, etc., in addition to gear tooth sensors that can detect metal. Gear tooth sensors are not displayed when selecting the subcategory Metal Detectors because they are located under motion sensors.

Industrial Sensors – Considerations

Different kinds of infrared light are used in infrared sensors. All objects emit infrared radiation, according to some. Others emit infrared beams that are reflected back to sensors that examine the beams for interruptions.

Temperature sensors typically rely on RTDs or thermistors to detect temperature changes caused by changes in materials’ electrical resistance.

Non-reaching vicinity sensors frequently use lobby impact peculiarities, vortex flows, or capacitive impacts to distinguish the closeness of conductive metals. Additionally utilized are optical and laser methods. Simple on/off proximity switches use the same techniques to detect an open door, for example, as proximity sensors can be used to detect minute shifts in the positions of targets.

To determine the distance to a tank’s contents, for instance, ultrasonic sensors measure the time between the emission and reception of ultrasonic waves. Ultrasonic sensors also detect the ultrasonic energy released by air leaks, for example.

Strain gages or piezoelectric devices, which change their resistance characteristics when loads are applied, are typically used in force and pressure sensors. These progressions can be aligned over the straight scopes of the transducers to deliver proportions of weight (power) or strain (force per unit region).

Vision sensors normally depend on CCD, infrared, or bright cameras to deliver pictures that can be deciphered by programming frameworks to identify defects, sense standardized tags, and so on.

Important Attributes

Types of Sensors/Detectors/Transducers

Many of the subcategories share similar sensor types. Hall effect sensors, for instance, can be found in a variety of sensors, including level sensors, motion sensors, and so forth. Level measurement, flame detection, and other applications call for infrared sensors. There are a variety of sensor types that can be used to measure the fuel level in a tank, for example.

Intended Application

Choosing an intended application can help narrow down options in certain situations. For instance, proximity sensors for pneumatic cylinders are made to attach directly to the tie rods of the cylinder and have particular mounting arrangements, as can be seen on the right.

Output Types

Current loops of 4-20 mA are used by many control sensors, with 4 mA representing the low end of the analog signal and 20 mA representing the high end. Advanced switches are utilized too, among them NPN/PNP, USB, and so on.

Response Time

While sensors for gases, leaks, etc. have response times measured in milliseconds, many others may be measured in seconds or even minutes for their response times.


sensors that are made to work in extreme conditions, dangerous places, etc. can be picked out here.

Related Product Categories

Electromechanical devices known as encoders are used to transform rotary or linear motions into analog or digital output signals.
Mechanical or electronic Load Cells are made to turn compressive, tensile, torsional, or shear forces into electrical signals.
Typically, monitors are electronic devices used to view information remotely or conveniently when needed.
Data Loggers are electronic data storage devices that are used to gather and record various data-over-time measurements. Data Acquisition Systems (abbreviated DAQ or DAS) collect analog signals from sensors measuring real-world samples and convert them into digital formats that are processed by Data Acquisition Systems.
Switches are electromechanical gadgets that are utilized in electrical circuits.
Mechanical thermocouples are used to measure temperature and are made of dissimilar metal wires that have been welded together.
Check out our Controls and Controllers Buyer’s Guide for more information.

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