Different Types of Sensors and Their Applications

Picture of John Gieske

John Gieske

Principal Engineer - LTE / 5G
types os sensors

Can you think of a world without sensors? A world where our smartphones can’t detect our touch, cars can’t sense obstacles, and medical devices can’t monitor vital signs. More precisely, it is a world where technology is blind, deaf, and unresponsive. No, the presence of different types of sensors has vanished such emptiness of the world.

Sensors detect changes in their environment and convert them into signals that an observer or an instrument can read. One more thing: by sensors, it doesn’t mean only physical elements that make it. It includes its physical packaging, external connections, and associated signal-processing hardware. 

This repetitive duty of sensors has made our lives incredible as we use them in different fields, from industry to education, from farming to medicine. In this blog, I will explain different types and examples of sensors and their functions. I hope you will love to read it.

Sensors can perform versatile operations that make them separate from each other. In general, we can classify sensors into four types:

Active Sensors

Active sensors require an external power source to function. They provide the majority of the output power of the signal. 

These sensors are classified into various types. Some of them are:

  • Accelerometers
  • Light sensors
  • Sound sensors
  • Pressure sensors
  • Temperature sensors

Passive Sensors

According to a study, passive sensors generate their own electric signal. There is no requirement for any external power source. Hence, this sensor technology gathers data by detecting vibrations, light, radiation, heat, or other phenomena.

Some examples of technologies that use passive sensors are:

  • Photographic
  • Thermal
  • Electric field sensing
  • Chemical
  • Infrared
  • Seismic

Analog Sensors

Analog sensors produce a continuous output signal or measurement. The classification of analog sensors is the same as active sensors.

The analog signals are directly proportional to the measurement. They have infinite possible values within a specific range. For instance, an analog sensor detecting changes in external parameters like wind speed or light intensity can give an output anywhere between its output range, like 0V to 5V.

Digital Sensors

Digital sensors include digital accelerometers and digital temperature sensors. In simple words, they are digitalized versions of analog sensors.

These sensors typically use pulse width modulation to generate output pulses. Likewise, they produce a binary signal, which means the signal is either on or off, representing a series of 1s and 0s.

Typically, digital sensors are used in systems where the presence or absence of something is being detected. Some examples of devices with these sensors are push buttons or light switches that indicate whether a device is on or off. 

Different Types of Sensors

Till now, I have classified the sensors into four main categories. However, all these sensors may function significantly. For their purpose of application, we can differentiate sensors into many types. Check out the list of sensors you can use for industrial purposes from Nybsys.

Accelerometer Sensors

These sensors work by measuring either static or dynamic acceleration through an electromechanical sensor. Usually, you can measure the displacement of a mass with a position-measuring interface circuit using these sensors. The accelerometer converts the displacement into a digital electrical signal for processing.  

The measured acceleration forces can be static (like constant gravity force) or dynamic to sense movement or vibrations. However, some accelerometers (like piezoelectric accelerometers) operate by producing a change in electrical charge proportional to the amount of force applied.

In various industries and fields, you can find the use of accelerometer sensors. Particularly, these sensors are common in navigation and control applications.

Gyroscope Sensors

A gyroscope sensor operates on the principle of angular momentum and gravity. It uses these forces to determine orientation and measure rotational motion. This type of sensor has a spinning rotor to provide angular momentum. Also, there is a set of gimbals or pivoted supports to allow the rotor to rotate about a single axis.

Gyroscopes can sense an angular velocity if the frame is rotating, with units of angular velocity measured in degrees per second or revolutions per second. Then, the measurement is converted into a digital electrical signal for digital processing.

Well, these sensors are applicable in applications like camera-shake detection systems, motion sensing for video games, and vehicle electronic stability control systems.

Temperature Sensors

Like the name, temperature sensors can detect thermal parameters. After detection, they provide signals to the inputs of used devices. However, these sensors are available in different types depending on their applications. Some technologies where you can use temperature sensors are AC and heating systems, microwaves, industrial machines, and aircraft.

The most commonly used types in modern electronics are thermocouples, resistance temperature detectors (RTDs), thermistors, and semiconductor-based integrated circuits (IC).

Contact temperature sensors require physical contact with the object to measure its temperature and can be used for solids, liquids, or gases. On the other hand, non-contact sensors detect temperature using radiation or convection.

Vision and Imaging Sensors

Vision sensors detect the presence of objects or colors within their fields of view. After that, they convert this information into a visual image for display. However, these sensors use a combination of image acquisition and image processing. They can perform multi-point inspections using a single sensor.

You can find these sensors in two types: monochrome and color. These imaging sensors can perform color and shape differentiation. Usually, they are used in measurement, pass/fail decisions, and other observable characteristics relating to product quality.

Some notable applications of vision sensors are visual tracking, detection, recognition, reconstruction, and stereo matching.

Proximity Sensors

Proximity sensors operate on various scientific principles to detect the presence or absence of objects without physical contact. They convert the detected information into an electrical signal.

You can find some common types of proximity sensors like capacitive, inductive, ultrasonic, optical, and acoustic sensors. However, the object’s surface color does not affect them. These sensors are applicable in a wide temperature range for versatile applications.

Proximity sensors are mostly used in automation, safety systems, and operational controls in various industries. Particularly, you can see their usage in molding, packaging, printing, and food and chemical processing. In these areas, contact with the object may cause damage or abrasion, which these sensors avoid.

Infrared Sensors (IR Sensors)

Objects above absolute zero (0°) temperature emit heat energy in infrared radiation form. This is the core principle of IR sensors. Using these sensors, you can emit or detect infrared radiation to sense specific characteristics of their surroundings. It includes the motion and heat of the objects. 

Infrared sensors usually have an infrared LED and an infrared photodiode. Together these components form a photo-coupler or optocoupler. Thus, these sensors are present in applications like radiation and spectrum measurement, search and track systems, thermal imaging systems, and gas detection.

Passive infrared sensors use a pair of pyroelectric sensors. They can detect heat energy in the surrounding environment

Radiation Sensors

You may know it as radiation detectors, too. These sensors measure radiation emissions or levels of radiation that a source produces.

Radiation sensors can detect different radiations like gamma and x-radiation. The uses of these sensors are present in tasks including measurement, protection, and search.

As the world has seen advancements in optical fiber-enabled radiation sensors, they offer improved sensitivity and sensing coverage. Yet the shape, length, and connection process of the extrinsic sensing materials can limit their application.

Position Sensors

Linear, rotary, and angular-  these three types of position sensors based on contact and non-contact technologies are available. However, some specific sensors are capacitive displacement sensors, linear potentiometers, and eddy current sensors.

Capacitive sensors determine the difference in voltage applied to the sensor and the target object. Then, linear potentiometers measure displacement by producing a resistive output proportional to the target object’s displacement.

Inductive position sensors operate on the principle of the AC transformer. They do not suffer from mechanical wear problems. Besides, there are contact position sensors, which operate by two objects touching and squeezing..

Pressure Sensors

These sensors work by following the principle of piezoresistance or piezoelectric effect. In this principle, a change in pressure leads to a change in electrical resistance or generation of an electrical charge.

The most common constructions of pressure sensors include a force collector (like a flexible diaphragm) and a transduction element with electrical signal generation. Once the sensor receives the signal, it translates the signal into a quantitative value for the pressure. Some pressure sensors can produce a strain gauge output like a Wheatstone bridge device.

Particle Sensors

Depending on the applications, these particle sensors are categorized into aerosol, solid, and liquid particle sensors. For instance, aerosol particle sensors can determine air quality. They can count and size the number of air particles. In food packaging, businesses use metal-based nanoparticles in their sensors.

Then, you can find particle filters (a type of sensor) in robot localization, SLAM, and robot fault diagnosis. Similarly, nanomaterial-based electrochemical sensors measure the concentration of targeted analytes via changes in current, potential, conductance, or impedance.

Photoelectric Sensors

Photoelectric sensors have an emitter for emitting light and a receiver for receiving light. They work following two principles: beam interruption and beam reflection.

When the emitter sends a light beam out, the sensing object interrupts or reflects it. In this process, it changes the amount of light that arrives at the receiver. Then, the receiver detects the intensity change of light and converts it to an electrical output.

Ultrasonic Sensor

Ultrasonic sensors can determine the distance to an object. They emit ultrasonic waves and measure the time taken for these waves to bounce back after hitting the object.

The effective range of these sensors can vary. It can be from a few centimeters to several meters, depending on the sensor and object properties. However, most sensors use the principle of measuring the propagation time of sound between send and receive.

Some ultrasonic sensors use piezoelectric ceramics for transmission and reception. They generate electromotive force in proportion to the amount of mechanical force applied.

Level Sensors

Different types of liquid level sensors are available, like ultrasonic, vibrating or tuning fork, and pulse level sensors. I have already talked about the ultrasonic sensors.

Vibrating or tuning fork sensors use a piezoelectric crystal or other technology to vibrate a probe. Then, they monitor the presence, absence, increase, or decrease of that vibration.

Float level sensors measure the position of a float on a vertical axis as the level of a liquid changes. Some other level sensors are rotating paddle, mechanical (diaphragm), microwave (radar), capacitance, optical, pulsed-ultrasonic, and glass level gauge.

Leak Sensors

Leak sensors can detect leakages. You can find many popular water leak detectors in the current market. Some detectors can even detect low temperatures and humidity.

These sensors may have a water-sensing cable. You can expand it up to 10 feet and a 105 dB siren. Some others may come with automatic shut-off valves. However, these sensors are effective in detecting the presence of acids, oils, chemicals, or other non-conductive fluids

Metal Sensors

We all have seen these sensors as they are known as metal detectors. These are electronic or electro-mechanical devices used to sense the presence of metal in various situations. You can permanently install these sensors or use them as portable devices.

A very common metal sensor is the inductive proximity sensor. It uses inductance principles to detect the presence of a metal target without making any physical contact. Then, metal oxide-based nano-biosensors have been used for biosensor development. They are also found as sensing layers in screen-printing pH sensors.

Motion Sensors

These sensors are available in different types like passive infrared (PIR), microwave, dual tech or hybrid, ultrasonic, and tomographic. PIR sensors are common in office and restroom applications. They can detect the infrared energy radiated from living beings.

Microwave sensors measure movement through microwave pulses. Then, dual tech/hybrid sensors use different tech combo to improve accuracy and reduce false alarms. Tomographic sensors detect disturbances in radio waves as they pass through walls and other obstacles.

The application of motion sensors is notable in many industries. They include automation, robotics, embedded systems, computers, and smart cars. Even they are used in home security systems to detect body heat and changes in temperature.

Some of them are known as gesture sensors, as they can control various electronic devices through gesture operations. Other motion sensors can monitor device movements such as tilt, shake, rotation, or swing.

Gas and Chemical Sensors

These sensors function differently and use significant technologies. Some of them are active as they do not need any external power source. Others may require external power to function.

Chemical sensors respond to a specific analyte selectively and reversibly. They transform the input chemical quantity into an analytically electrical signal.

Gas sensors can sample gas by diffusion, pumped transport, or via remote optical sampling methods. Polymers, metal-oxide-based semiconducting materials, and porous silicon are used in gas sensing research.

Some sensors use chemiresistive and FET technologies. Others may use carbon materials, 2D TMDCs, and metal/metal oxide.

Force Sensors

These transducers convert mechanical input forces into an electrical output signal. The most common force sensors include Load Cells, Strain gauges, and Force Sensing Resistors (FSRs). You can find the use of these sensors in load cells like pneumatic, capacitive, strain gage, hydraulic, and bolt load sensors.

These sensors help to weigh objects, prevent machinery from overloading, and measure tension, compression, torque, strain, stress, or pressure. Flexible force sensors are rapidly developing in the intelligent wearable technology field.

Humidity Sensors

If you want to measure the amount of water present in the surrounding air, you can use humidity sensors. They have a humidity-sensing element and a thermistor to measure the temperature. Hence, their principle of functioning is detecting changes that alter electrical currents or temperature in the surrounding air.

Three main types of humidity sensors are out there: capacitive, resistive, and thermal. Capacitive sensors use a capacitor as the sensing element. They measure the change in electrical permittivity of the dielectric material to calculate the relative humidity values. Then, resistive humidity sensors use a moisture-absorbing (hygroscopic) material.

Electrical Sensors

These sensors detect the changes in their environment. Then, convert those changes into electrical signals. Thus, you can classify them based on the physical parameters they sense, their applications, or the industry in which they are used.

Some notable electrical sensors are temperature sensors, thermocouple sensors, and proximity sensors. You can find the applications of electrical sensors in railway systems, fan, pump, and heater monitoring.

Flaw Sensors

Flaw sensors are used in non-destructive testing to detect surface inconsistencies. They employ methods like ultrasonic or eddy-current testing to identify defects in materials.

Ultrasonic testing uses high-frequency ultrasound waves to perform inspections and measurements. It can discover and evaluate flaws, measure dimensions, and characterize materials. Consequently, this method works by sending high-frequency sound waves through a material and analyzing the echoes that come back.

On the other hand, Eddy’s current testing uses the principle of electromagnetism for flaw detection in conductive materials.

Flow Sensors

You can measure the flow rate or quantity of a moving liquid or gas using flow sensors. These sensors can be classified into various types. They can be positive displacement, differential pressure, thermal, target, paddle wheel, and magneto-inductive sensors.

Positive displacement sensors measure the fluid’s volume directly when passing through the device. Differential pressure flow sensors are popular due to their cost, performance, and versatility. Then, thermal flow sensors are used in healthcare and industries for tracking flow intensities.

Flow sensors are found in measuring oils, gasoline, hydraulic fluid, and home-installed metering of water and gas. Also, they have automotive applications like measuring air entering the air intake system of an engine.

Flame Sensors

Flame sensors are optoelectronic devices. These sensors can detect the presence and quality of fire. Once detected, they send signals to control devices. Usually, you can find these sensors as ultraviolet, infrared, multi-spectrum infrared, and IR3 flame sensors.

Ultraviolet flame sensors can detect ultraviolet radiation, which most fires emit. Infrared flame detectors monitor the infrared spectral band for specific patterns given off by hot gases. Hence, these sensors are used in oil and gas pipelines, turbine enclosures, manufacturing facilities, power plants, and more.

As these sensors are sensitive to normal light, many people use them in flame alarms. Some of their types, like the QFCE digital flame sensors, are a good choice for IoT and industrial IoT applications. They have high sensitivity, reliability, and high detection range.

Contact Sensors

Contact sensors like thermistors can change their resistance with temperature. You can identify or categorize them as positors if the resistance increases with temperature. However, contact sensors can also be part of a system that includes a sensor and magnet. They can alert you when you open and close the door or window.

Another type of these sensors, contact positioning sensors, can measure the position of a target by directly contacting it. Usually, these sensors are divided into two groups. One group uses a “differential transformer” method with a magnetic coil. Another one uses a “scale” method with an internal scale.

You can also find contact temperature sensors. They may consist of thermocouples, thermistors, and resistance temperature detectors. Likewise, these sensors can measure temperature through various methods (like voltage difference).

Non-Contact Sensors

There is no need for physical contact or mechanical movement to obtain readings if you use non-contact sensors. They rely on technologies based on electrical, magnetic, optical, or sonic principles.

The applications of non-contact sensors are notably present in remote sensing of material properties, displacement, vibration, and distance. They are also used in healthcare for remote health applications. Doctors can monitor vitals in intensive care. On the other hand, traditional contact sensors can cause discomfort or damage to the skin.

Application of Sensors

So, what are sensors used for? In many spheres of our life, from home to office, from school to factory, we can use sensors through sensor and control devices

Home Automation System

Do you want to upgrade your lifestyle at home? If so, you can utilize various types of sensors to enhance functionality and security. Some examples of helpful sensors for home automation systems are motion, fire, humidity, temperature, leak, and motion.

Intrusion Prevention System

Network-based intrusion detection systems (NIDS) have sensors strategically placed within the network. They help to monitor as much traffic as possible without creating performance bottlenecks. Also, they identify illegal or rogue control points and changes in behavior to prevent intrusion. Contact, radiation, motion, metal, and ultrasonic sensors are helpful in this case. 

Fire Prevention System

Fire prevention systems with sensor technology can detect the potential of a fire starting. They alert occupants or automatically shut off devices to prevent a fire. Thus, flame sensors can be helpful to detect any presence of fire. They may detect the early development of fires to prevent and minimize human and property loss. 

Server Room Monitoring

You can use versatile sensors to ensure optimal conditions and prevent equipment failure in the server room. In this case, sensors like temperature, humidity, leak, flame, gas, and non-contact can be very useful. 

Agriculture Monitoring

Using sensors in different fields of agriculture can make it more efficient and sustainable. Some of the specific ways in which sensors are being used in agriculture include: monitoring soil moisture levels, measuring nutrient levels, tracking the growth of crops, detecting pests, and observing livestock. Check out Nybsys Smart Agriculture Monitoring System for more regarding this.

Vehicle Management

In the field of transportation, sensor technology is widely used for various applications like traffic control, vehicle tracking, speed measurements, and traffic estimation. Sensors integrated into vehicles and infrastructure provide a transparent view of potential threats and hazards. So you can remain safe on the roads. We offer sensor and other vehicle management services (Connected Transportation) from Nybsys. 

Industrial Automation

Sensors can help to optimize production and operations. In this case, I suggest you check out our Smart Factory products and services to learn about relevant sensors. Thus, temperature, humidity, proximity, ultrasonic, particle, flame, flow, flaw, gas, and chemical sensors can be useful to upgrade your industry to a new level

Environment Monitoring System

Sensors can collect real-time data on various environmental parameters like quality of air and water, soil conditions, and weather conditions. In an environment monitoring system, some standard sensors used are temperature, humidity, gas, water quality, soil, and weather sensors to monitor pollution, resource management, and protect the environment.

Parking Guidance System

Using different sensor technologies in the parking guidance system can provide real-time info regarding available parking spaces, enhancing the parking experience and optimizing parking lot usage. Some notable sensors that can be applied in this system are infrared, gyroscope, position, and wireless sensors. 

Time and Attendance System

Sensors can play a vital role in the modern time and attendance systems. They can enable accurate and contactless employee registration. These sensors capture unique employee identifiers, like fingerprints, iris patterns, or facial features. After collecting the information, they can transmit it to a central database.

Access Control System

Access control systems employ various sensors to ensure security and prevent unauthorized access. These include physical presence sensors that can detect flame, metals, leaks, levels, gas, and chemicals. Other components of physical access control systems include access points such as commercial door locks, turnstiles, and security gate systems. 

Final Words

Sensors can change the way of our vision by enabling safe and swift access to technology. From early morning to late night, wherever we are, we can use things that run with or depend on these sensors. 

In this blog, I have discussed a lot of different types of sensors with their applications. Besides, you have learned about the category of sensors depending on which principles they follow to work. If you have any questions, please let us know.

Nybsys Industrial Sensors are great products for any industrial purpose. We can turn your business automated with full safety and speed. Please, contact us directly for further queries!

Thank you.

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