In the article today, we will introduce you 7 commonly used sensor technologies.CatalogI. IntroductionII. Seven Commonly Used Sensor Technologies2.1 Physical Sensor2.2 Optical Fiber Sensor2.3 Bionic Sensor2.4 Infrared Sensor2.5 Electromagnetic Sensor2.6 Magneto-optic Effect Sensor2.7 Pressure SensorFAQI. IntroductionThe sensor is a common but very important device, it is a device that feels the specified amount of measurement and converts it into a useful signal according to a certain law. For the sensor, according to the state of the input, the input can be divided into static and dynamic quantities. We can obtain the static characteristics of the sensor according to the relationship between the output and the input in the stable state of each value.The main indexes of the static characteristics of the sensor are linearity, hysteresis, repeatability, sensitivity, and accuracy. The dynamic characteristics of the sensor refer to the response characteristics of the input, which changes with time. The dynamic characteristics are usually described by automatic control models such as transfer function and so on. Usually, the signal received by the sensor has a weak low-frequency signal, sometimes the amplitude of external interference can exceed the measured signal, so eliminating the serial noise has become a key sensor technology.II. Seven Commonly Used Sensor Technologies2.1 Physical SensorA physical sensor is a sensor that detects physical quantities. It is a device that uses some physical effects to convert the measured physical quantity into a signal in the form of energy that is easy to process. There is a definite relationship between the output signal and the input signal. The main physical sensors are photoelectric sensor, piezoelectric sensor, piezoresistive sensor, electromagnetic sensor, thermoelectric sensor, optical fiber sensor, and so on. As an example, let's take a look at the more commonly used photoelectric sensors. The sensor converts the optical signal into an electrical signal, which directly detects radiation information from the object, and can also convert other physical quantities into optical signals.The main principle is the photoelectric effect: when light shines on the material, the electrical effect on the material changes, where the electrical effect includes electron emission, conductivity, and potential current. Obviously, devices that can easily produce such an effect have become the main components of photoelectric sensors, such as photoresistors. In this way, we know that the main workflow of the photoelectric sensor is to receive the corresponding light, convert the light energy into electric energy through devices such as photoresistors, and then process it by amplifying and removing noise. Thus you will get the electrical signal you need to output. The output electrical signal here has a certain relationship with the original optical signal, usually close to a linear relationship, so that the calculation of the original optical signal is not very complex. The principle of other physical sensors can be analogous to photoelectric sensors.The application of physical sensors is very extensive. For example, let’s take a look at the application of physical sensors from the perspective of biomedicine. It is not difficult to speculate that physical sensors also have important applications in other aspects.Blood pressure measurement, for example, is one of the most conventional medical measurements. Our usual blood pressure measurements are indirect, through the relationship between the blood flow and pressure detected on the body surface, so as to measure the blood pressure in the pulse tube. The sensors needed to measure blood pressure usually include an elastic diaphragm that converts the pressure signal into the deformation of the diaphragm and then converts it into a corresponding electrical signal according to the strain or displacement of the diaphragm. We can detect the systolic blood pressure at the peak of the electrical signal. After the inverter and the peak detector, we can get the diastolic pressure through the shape of the sensor, and we can get the average pressure through the integrator.Next, let's take a look at respiration measurement. Respiratory measurement is an important basis for clinical diagnosis of pulmonary function and is essential in surgery and patient monitoring. For example, when a thermistor type sensor for measuring respiratory frequency is used, the resistance of the sensor is mounted on the outer side of the front end of a clip. And then clamp the clip on the nasal wing. When the respiratory airflow flows through the surface of the thermistor, the frequency of breathing and the state of the hot gas can be measured by thermistors.Here is another example. Although the most common body surface temperature measurement process seems easy, there is a complex measurement mechanism. Body surface temperature is determined by many factors, such as local blood flow, heat conduction of lower tissue, and heat dissipation of the epidermis. So, many effects should be taken into account in measuring skin temperature. Thermocouple sensors are widely used in temperature measurement, usually, there are rod thermocouple sensors and thin-film thermocouple sensors. Because the size of the thermocouple is very small and the precision is high enough to reach the micron level, the temperature at a certain point can be measured more accurately. Coupled with the later analysis and statistics, a more comprehensive analysis result can be obtained. This is incomparable to the traditional mercury thermometer, and also shows the broad prospects for the application of new technology to the development of science.From the above introduction, it can be seen that physical sensors have a variety of applications in biomedicine alone. The development direction of sensors is multi-functional, image-based, and intelligent sensors. Sensor measurement, as an important means of data acquisition, is an indispensable device in industrial production and even family life. And the physical sensor is the most common sensor family. Flexible use of the physical sensors is bound to create more products and bring better benefits.2.2 Optical Fiber SensorIn recent years, sensors are developing in the direction of sensitivity, accuracy, adaptability, small size, and intelligentization. In this process, the optical fiber sensor, a new member of the sensor family, is very popular. Optical fiber has many excellent properties. For example, the performance of resistance to electromagnetic interference and atomic radiation, the mechanical properties of fine diameter, soft and lightweight, the electrical properties of insulation and non-induction, the chemical properties of water resistance, high-temperature resistance and corrosion resistance, etc., It can play the role of human eyes and ears in places that are not accessible to people (such as high-temperature zones) or harmful areas (such as nuclear radiation areas). It can also go beyond the physiological boundaries of people and receive external information that cannot be felt by people's senses.Optical fiber sensor is a new technology in recent years, which can be used to measure a variety of physical quantities, such as sound field, electric field, pressure, temperature, angular velocity, acceleration, and so on. It can also complete the measurement tasks that are difficult to be completed by the existing measurement technology. In a narrow space, strong electromagnetic interference, and high voltage environment, optical fiber sensors have shown a unique ability. At present, there are more than 70 kinds of optical fiber sensors, which are roughly divided into optical fiber self-sensors and optical fiber sensors.The so-called optical fiber self-sensor is that the optical fiber itself directly receives the measurement from the outside world. The external measured physical quantity can cause the change of the length, refractive index, and diameter of the measuring arm, which makes the light transmitted in the optical fiber change in amplitude, phase, frequency, polarization, and so on. The light transmitted by the measuring arm interferes (compares) with the reference light of the reference arm so that the phase (or amplitude) of the output light changes. According to this change, the measured change can be detected. The phase transmitted in the optical fiber is highly sensitive to the influence of the outside. The physical quantity corresponding to the small phase change of the negative fourth power radian of 10 can be detected by using interferometry. By using the winding and low loss of the fiber, the very long fiber disk can be formed into a small optical fiber ring, in order to increase the utilization length and obtain higher sensitivity.An optical fiber acoustic sensor is a kind of sensor that uses optical fiber itself. When the optical fiber is subjected to a very small external force, it will produce micro-bending, and its light transmission ability will change greatly. Sound is a kind of mechanical wave, its effect on optical fiber is to force and bend the optical fiber, and it can get strong and weak sound through bending. A gyroscope is also a kind of optical fiber self-sensor. Compared with laser gyro, the gyroscope has the advantages of high sensitivity, small size, and low cost. It can be used in the high-performance inertial navigation systems of aircraft, ships, missiles, and so on.Another large class of optical fiber sensors is the sensor that uses optical fiber. The structure is roughly as follows: the sensor is located at the end of the optical fiber, the optical fiber is only the transmission line of light, which transforms the measured physical quantity into the amplitude, phase, or amplitude change of the light. In this kind of sensor system, the traditional sensor and optical fiber are combined. The introduction of optical fiber makes it possible to realize probe telemetry. The sensor transmitted by optical fiber has a wide range of applications and is easy to use, but the accuracy is slightly lower than that of the first kind of sensor.Optical fiber is a rising star in the sensor family. It has been widely used because of its excellent performance, and it is a kind of sensor worthy of attention in production practice.2.3 Bionic SensorThe bionic sensor is a new type of sensor that adopts a new detection principle. It uses immobilized cells, enzymes, or other bioactive substances to combine with the transducer to form the sensor. This kind of sensor is a new type of information technology developed by the mutual penetration of biomedicine, electronics, and engineering in recent years. This kind of sensor is characterized by high function and long life. Among the bionic sensor, the biological simulation sensor is more commonly used.Bionic sensors can be divided into enzyme sensors, microbial sensors, organelle sensors, tissue sensors, and so on according to the medium used. In the figure, we can see that bionic sensors are closely related to all aspects of biological theory, which is the direct result of the development of biological theory. In the biological simulation sensor, the urea sensor is a recently developed sensor. The following is an example of a urea sensor to introduce the application of a bionic sensor.Urea sensor is mainly composed of a biological membrane and its ion channel. The biological membrane can feel the effect of external stimulation, and the ion channel can receive the information of the biological membrane and then amplify and transmit it. When the sensory part of the membrane is affected by external stimulants, the permeability of the membrane will change, so that a large number of ions flow into the cell, forming the transmission of information. Among them, the component of the biological membrane is the membrane protein, which can produce the change of the conformal network, change the permeability of the membrane, transmit and amplify the information. The ion channel of the biological membrane, which is composed of amino acid polymers, can be replaced by L-glutamic acid, PLG, which is easy to synthesize in organic chemistry and has better chemical stability than enzymes.PLG is water-soluble and is not suitable for motor modification, but PLG and polymers can synthesize block copolymers to form induction films used in sensors. The principle of the ion channel of the biological membrane is basically the same as that of the biological membrane. After the block copolymer membrane is fixed at the electrode, if the substance sensing the change of the PLG retention network is added, the permeability of the membrane will change, resulting in the change of the current. By the change of current, the irritant substance can be detected. The urea sensor has been proved to be a kind of biological analog sensor with good stability. The detection limit is 10 of the order of minus 3, and the irritant can also be detected, but by now it is not suitable for the measurement of the biological body for the time being.At present, although many bionic sensors have been developed successfully, the stability, reproducibility, and batch productivity of bionic sensors are obviously insufficient, so bionic sensing technology is still in its infancy. In the future, in addition to continuing to develop a new series of bionic sensors and improve the existing series, the immobilization technology of bioactive membrane and the solid-state of bionic sensors are worthy of further study.In the near future, bionic sensors simulating the functions of the living body, such as smell, taste, hearing, and touch will appear, and it may exceed the sensitivity of human facial features. At the same time, it will improve robots’ vision, taste, touch, and ability to operate objects. We can see the broad prospects for the application of biomimetic sensors, but these need the further development of biotechnology. Let’s wait and see the arrival of this day.2.4 Infrared SensorUp to now, infrared technology has been well known. This kind of technology has been widely used in modern science and technology, national defense, industry and agriculture, and other fields. An infrared sensing system is a measurement system with an infrared medium, which can be divided into five categories according to its functions:（1）Radiometer for radiation and spectral measurement;（2）Searching and tracking system for searching and tracking infrared targets so as to determine its spatial position and track its motion;（3）The thermal imaging system can generate the distribution image of the whole target infrared radiation;（4）The infrared ranging and communication system;（5）Hybrid system refers to the combination of two or more of the above types of systems.The core of the infrared system is the infrared detector. According to the different detection mechanisms, it can be divided into two categories: a thermal detector and a photon detector. The following is an example of a thermal detector to analyze the principle of the detector.The thermal detector makes use of the radiation thermal effect to cause the temperature to rise after the detector receives the radiation energy, and then causes the performance which depends on the temperature in the detector to change. Radiation can be detected by detecting changes in one of these properties. In most cases, radiation is detected through thermoelectric changes. When the element receives radiation and causes the physical change of the non-electric quantity, the corresponding electric quantity change can be measured after the appropriate transformation.2.5 Electromagnetic SensorThe magnetic sensor is the oldest sensor; a compass is the earliest application of a magnetic sensor. However, as a modern sensor, in order to facilitate signal processing, magnetic sensors are needed to convert magnetic signals into electrical signals. The earliest application is the magnetoelectric sensor made according to the principle of electromagnetic induction. This magnetoelectric sensor has made outstanding contributions in the field of industrial control, but today it has been replaced by a new type of magnetic sensor based on high-performance magnetic sensitive materials.Among the electromagnetic effect sensors used today, the magnetic rotation sensor is an important one. The magnetic rotation sensor is mainly composed of semiconductor magnetoresistive elements, permanent magnet, retainer, shell, and so on. The typical structure is that a pair of magnetoresistive elements are installed on the stimulation of a permanent magnet, the input and output terminals of the elements are connected to the fixator, and then installed in a metal box. Next, seal it with engineering plastic to form a closed structure. This structure has good reliability. The magnetic rotation sensor has many advantages over the shape of an electromagnetic sensor. In addition to high sensitivity and large output signal, it has a strong speed detection range, which is due to the development of electronic technology. In addition, the sensor can also be used in a wide temperature range. It has a long working life, strong resistance to dust, water, and oil, so it can withstand a variety of environmental conditions and external noise. Therefore, this kind of sensor has been paid more and more attention in industrial applications.The magnetic rotation sensor is widely used in factory automation systems because it has satisfactory characteristics and does not need to be maintained. It is mainly used in the rotation detection of machine tool servo motor, the positioning of factory automated robot arm, the detection of hydraulic stroke, the position detection of factory automation related equipment, the detection unit of a rotary encoder, and various rotating detection units, and so on. Modern magnetic rotation sensors mainly include four-phase sensors and single-phase sensors. In the working process, the four-phase differential rotation sensor uses one pair of detection units to realize differential detection, and the other pair to realize reverse differential detection. In this way, the detection ability of the four-phase sensor is four times that of a single element. The two-element single-phase rotation sensor also has its own advantages, that is, small, reliable, and low cost. At the same time, it has a large output signal, strong ability of anti-environmental impact and anti-noise and it can detect low-speed motion. Therefore, single-phase sensors will also have a good market.Magnetic rotation sensors also have great application potential in household appliances. In the reversing mechanism of a cassette recorder, a magnetoresistive element is available to detect the endpoint of the tape. Most of the household video recorders have variable speed and high-speed playback functions, which can also use a magnetic rotation sensor to detect and control the spindle speed to obtain a picture of high quality. The positive and negative rotation and high and low-speed rotation functions of the motor in the washing machine can be detected and controlled by a servo rotation sensor. This switch can sense the metal object entering its own inspection area and control the opening or closing of its own internal circuit. The switch itself produces a magnetic field. When a metal object enters the magnetic field, it causes a change in the magnetic field. This change can be converted into an electrical signal through the internal circuit of the switch.2.6 Magneto-optic Effect SensorModern electrical measurement technology is becoming more and more mature. Because of its high precision and convenience for microcomputer connection to achieve automatic real-time processing, it has been widely used in the measurement of electrical and non-electrical quantities. However, the electrical measurement method is easy to be interfered with. In AC measurement, the frequency response is not wide enough and has certain requirements for voltage and insulation. With the rapid development of laser technology today, it has been able to solve the above problems.Magneto-optic effect sensor is a high-performance sensor developed by laser technology. Laser is another new technology developed rapidly in the early 1960s. Its appearance indicates that people have entered a new stage of mastering and utilizing light waves. In the past, the single chromaticity of the ordinary light source is low. Therefore, many important applications are limited. With the emergence of laser, radio technology and optical technology are advancing by leaps and bounds, permeating and complementing each other. Now, many sensors have been made by using laser, which has solved many technical problems that cannot be solved before and makes it suitable for dangerous and flammable places such as coal mine, oil, natural gas storage, and so on.For example, the optical fiber sensor made of laser can measure the parameters of crude oil injection and crack of large oil tanks. In the measured location, there is no need for a power supply, which is especially suitable for petrochemical equipment groups with strict requirements for safety and explosion-proof measures. It can also be used to realize the telemetry chemical technology of optical methods in some links of large iron and steel mills.The principle of the magneto-optical effect sensor is to realize the function of the sensor by using the polarization state of light. When polarized light passes through a medium, if there is an external magnetic field in the direction of beam propagation, then the light will rotate an angle through the polarization surface, which is the magneto-optic effect. That is, the external magnetic field can be measured by rotating the angle. In a specific experimental device, the deflection angle is proportional to the output light intensity. The digital light intensity can be obtained by irradiating the laser diode LD, with the output light, which can be used to measure specific physical quantities.Since the end of the 1960s, RCLecraw has put forward the research report on the magneto-optic effect, which has attracted everyone's attention. Japan, the Soviet Union, and other countries have carried out research, domestic scholars have also explored. The magneto-optic effect sensor has characteristics of excellent electrical insulation performance, anti-interference, frequency response width, quick response, safe explosion-proof, and so on. Therefore, it has a unique effect on the measurement of electromagnetic parameters on some special occasions. Especially in the measurement of high voltage and current in power systems, it shows its potential advantages. At the same time, by developing the software and hardware of the processing system, the automatic real-time measurement of welding machines and robot control systems can also be realized.In the use of a magneto-optic effect sensor, the most important thing is to select a magneto-optical medium and laser. Different devices have different abilities in sensitivity and working range. With the emergence of high-performance lasers and new magneto-optical medium in recent decades, the performance of magneto-optical effect sensors is getting stronger and stronger, and the application is more and more extensive. As a special purpose sensor, the magneto-optical effect sensor can play its own function in a specific environment, and it is also a very important industrial sensor.2.7 Pressure SensorThe pressure sensor is the most commonly used sensor in industrial practice, and the pressure sensor we usually use is mainly made of piezoelectric effect, which is also called a piezoelectric sensor.We know that crystals are anisotropic and amorphous crystals are isotropic. When some crystal medium is deformed by a mechanical force in a certain direction, it produces a polarization effect; when the mechanical force is removed, it will return to the state of being uncharged, that is when it is subjected to pressure. Some crystals may produce the effect of electricity, which is called the polarization effect. Based on this effect, some scientists have developed pressure sensors.+The main piezoelectric materials used in piezoelectric sensors include quartz, potassium sodium tartrate, and dihydroamine phosphate. Quartz (silica) is a kind of natural crystal in which the piezoelectric effect is found. Within a certain temperature range, piezoelectric properties always exist. But after the temperature exceeds this range, the piezoelectric properties disappear completely (this high temperature is the so-called "Curie point"). Because the electric field changes slightly with the change of stress (that is to say, the piezoelectric coefficient is relatively low), quartz is gradually replaced by other piezoelectric crystals. Potassium sodium tartrate has high piezoelectric sensitivity and piezoelectric coefficient, but it can only be used at room temperature and in an environment with low humidity. Dihydroamine phosphate is an artificial crystal, which can withstand high temperature and high humidity, so it has been widely used. Nowadays, the piezoelectric effect is also used in polycrystals, such as piezoelectric ceramics, including barium titanate piezoelectric ceramics, PZT, niobate piezoelectric ceramics, lead magnesium niobate piezoelectric ceramics, and so on.The piezoelectric effect is the main working principle of the piezoelectric sensor. The piezoelectric sensor cannot be used for static measurement because the charge after external force can only be preserved when the loop has infinite input impedance. This is not the case, so it determines that piezoelectric sensors can only measure dynamic stress.Piezoelectric sensors are mainly used in the measurement of acceleration, pressure, and force. A piezoelectric accelerometer is a commonly used accelerometer. It has the advantages of simple structure, small volume, lightweight, long service life, and so on. The piezoelectric accelerometer has been widely used in aircraft, automobile, ship, bridge, the vibration of building and impact measurement, especially the shape of the piezoelectric sensor has its special position in the field of aviation and aerospace. It can also be used to measure the internal combustion pressure and vacuum of the engine. Moreover, it can be used in the military industry, for example, to measure the change in chamber pressure and the shock wave pressure at the muzzle of a gun bullet fired in the bore.It can be used not only to measure large pressure but also to measure small pressure. Piezoelectric sensors are also widely used in biomedical measurements. For example, ventricular catheterized microphones are made of piezoelectric sensors. Because the measurement of dynamic pressure is so common, piezoelectric sensors are widely used. In addition to piezoelectric sensors, there are piezoresistive sensors made by piezoresistive effect, strain sensors using strain effect, etc. These different pressure sensors can play their unique uses in different situations by using different effects and materials.FAQ1. What sensor means?a device that responds to a physical stimulus (such as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control) .2. What is the purpose of a sensor?A sensor converts the physical action to be measured into an electrical equivalent and processes it so that the electrical signals can be easily sent and further processed. The sensor can output whether an object is present or not present (binary) or what measurement value has been reached (analog or digital).3. How do sensors work?Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed.4. What can sensors detect?Broadly speaking, sensors are devices that detect and respond to changes in an environment. Inputs can come from a variety of sources such as light, temperature, motion and pressure.5. What are the importance of sensors in our daily life?Intelligent sensor systems are omnipresent in our everyday lives. They provide security, save lives and improve our quality of life. As more and more areas of life are automated and networked, the importance of innovative sensor technologies will also increase in the future.6. How do we classify sensors?Classification of Sensors:Active and Passive Sensors. Contact and Non-Contact Sensors.Absolute and Relative Sensors.Analog and Digital Sensors.Miscellaneous Sensors.7. How are sensors used to collect data?With a sensor, a machine observes the environment and information can be collected. A sensor measures a physical quantity and converts it into a signal. Sensors translate measurements from the real world into data for the digital domain.8. What is the difference between sensor and transducer?The main difference between sensor and transducer is that a transducer is a device that can convert energy from one form to another, whereas a sensor is a device that can detect a physical quantity and convert the data into an electrical signal.9. Why do we need a temperature sensor?Within our homes, temperature sensors are used in many electrical appliances, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters.10. How sensors are connected?A sensor device directly connected to a computer. A connected sensor is a sensor that also has a way to send data to either a local network or the Internet. Diagram of a sensor receiving waves on the left and broadcasting a wireless signal on the right to a router. A sensor device wirelessly connected to a network.11. Can a transducer be a sensor?A Sensor is defined as a device which measures a physical quality (light, sound, space) and converts them into an easily readable format. If calibrated correctly, sensors are highly accurate devices. Not all transducers are sensors but most sensors are transducers.12. What is the difference between active and passive sensors?Active sensors have its own source of light or illumination. In particular, it actively sends a pulse and measures the backscatter reflected to the sensor. But passive sensors measure reflected sunlight emitted from the sun. When the sun shines, passive sensors measure this energy.13. What are the basic characteristics considered in the process of sensor selection?Sensor selection criteria include temperature, size, protection class, and whether the sensor requires a discrete or analog input. Also consider sensor repetition accuracy, sensor response speed, and sensing range.14. What are the applications of sensors?Sensors are central to industrial applications being used for process control, monitoring, and safety. Sensors are also central to medicine being used for diagnostics, monitoring, critical care, and public health.15. How do you check the accuracy of a sensor?To find out the accuracy of sensor you have to take several readings by your sensor on that particular one input parameter (like. temperature). after accumulating those sensor output values evaluate the standard deviation as per law, which indicate the accuracy level of your sensor.
kynix On 2017-10-23
292
info@kynix.com
00852-6915 1330
