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  In daily production and life, ultrasonic ranging sensors are mainly used for non-contact automatic parking distance control (PDC) of automobiles, obstacle avoidance robots, construction sites and industrial working environments that require liquid level, well depth, pipeline length, etc. In general, there are two commonly used ultrasonic distance measurement methods:   - The ultrasonic ranging system based on single chip microcomputer or embedded equipment;   -  An ultrasonic ranging system based on CPLD (complex programmable logic device). In order to understand the design and application of ultrasonic ranging sensor, let us first understand the working principle of ultrasonic sensor. Introducing ultrasonic sensor & taking HC-SR04 as an example   Catalog   I What is ultrasonic sensor? II Methods for ultrasonic ranging III Principles for ultrasonic ranging IV Conclusion FAQ   I What is ultrasonic sensor?      Figure 1. Working principle of ultrasonic sensor ranging An ultrasonic sensor is a sensor that converts an ultrasonic signal into another energy signal (usually an electrical signal).  Ultrasonic is a mechanical shock wave generated in elastic media with a frequency greater than 20 kHz. Because of its strong directivity, slow energy consumption and relatively long propagation distance, it is often used in non-contact ranging.  In addition, ultrasonic has the big ability to penetrate liquid and solid, especially in the sunshine opaque solid. When an ultrasonic hits an impurity or an interface, itwill produce a significant reflection to form an echo,  and when it hits a moving object will cause a phenomenon called Doppler Effect.  Therefore, ultrasonic ranging has a good adaptability to the environment, and ultrasonic distance measurement can be well compromised in real time, precision, and price. II Methods for ultrasonic ranging At present, there are various methods for ultrasonic ranging:    -  round-trip time detection;   -  phase detection;   -  acoustic amplitude detection. The principle is that the ultrasonic sensor emits ultrasonic waves of a certain frequency, propagates through the air medium, and is reflected back after reaching the measurement target or the obstacle. After being reflected, the ultrasonic receiver receives the pulses, and the time it takes, is the round-trip time, which is related to the distance traveled by ultrasonic waves. Measuring the wave propagation time to get the wave propagation distance: Assuming that s is the distance between the measured object and the range finder, the time measured is t / s, and the velocity of ultrasonic propagation is expressed as v／m·s－1, then there is a relation (1): s=vt／2       (1) When the accuracy is required, the influence of temperature on the ultrasonic propagation speed needs to be considered, therefore the ultrasonic propagation speed is corrected according to relation (2) to reduce the error. v=331．4+0．607T        (2) Where T is the actual temperature, the unit is °C; v is the propagation speed of ultrasonic wave in the medium, and the unit is m/s. Figure 2. Working principle of ultrasonic ranging sensor   III Principles for ultrasonic ranging   The principle of ultrasonic ranging is to transmit ultrasonic waves in a specific direction through an ultrasonic transmitter, and start timing at the same time as the transmission. When ultrasonic waves propagate in the air and hit an obstacle, they will immediately return and be received by the ultrasonic receiver, and stop timing immediately. The ultrasonic ranging sensor uses the principle of ultrasonic echo ranging and uses precise time difference measurement technology to detect the distance between the sensor and the target. It has the advantages of small angle, small blind area, high measurement accuracy, non-contact ranging, waterproof, anti-corrosion, and low cost. Ultrasonic ranging sensors are usually used in a way that one transmitter corresponds to one receiver, but there are also multiple transmitters corresponding to one receiver. Therefore, the ultrasonic distance sensor can measure the return and return time of the ultrasonic wave to determine the distance of the object. This is how the ultrasonic distance sensor works. For the ultrasonic distance sensor, we recommend to use the Korean Hagisonic ultrasonic distance sensor module HG-C40U.   Figure 3. Ultrasonic distance sensor module HG-C40U   Ultrasonic distance sensor module has two optional transmission modes:   -  Free operation mode: when there is power supply, the sensor itself can send trigger and burst signals and it is usually for basic applications;   -  External trigger mode: the external system (controller or processor) controls trigger signals for advanced applications. These two modes are suitable for a variety of purposes.   In addition, the sensors also involve the choice of two input power supplies:   -  Low voltage (5V) for the processor circuit, the distance to the obstacle can be measured is 3.5m;   -  High voltage (12V) for the controller circuit, the distance to the obstacle can be measured is 5m. The data is transmitted by UART (universal asynchronous receiver-transmitter) with a resolution of less than 5mm. On the other hand, users can select different setting modes according to their own environment needs. Such as free-running / UART triggering / external trigger settings, etc.  At the same time, on the basis of baud rate of UART communication, the user can also decide whether to set up the circular buffer or not. The output signal uses high performance ASIC (application-specific integrated circuit) chip to ensure stable transmission and sensitive reception, and the communication between sensor and PC uses "interface board" (RS232, power regulator). The data show that the real received ultrasonic wave can be amplified in real time by using the monitor program on PC, the distance value can be output by UART (ASCII, mm), and then the detection signal can be converted into the rectangular TTL level signal (square wave) in real time. IV Conclusion Ultrasonic sensors are reliable, cost-effective and efficient solutions for distance sensing, level and obstacle detection. Once you understand how ultrasonic sensors work and which ultrasonic technology is most suitable rather than excellent, you can make more informed decisions about the correct sensor system for your application.   FAQ   1. What type of sensor is ultrasonic sensor? ultrasonic / level sensors measure the distance to the target by measuring the time between the emission and reception. An optical sensor has a transmitter and receiver, whereas an ultrasonic / level sensor uses a single ultrasonic element for both emission and reception.   2. How many types of ultrasonic sensors are there? four types. All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type).   3. What is the range of ultrasonic sensor? For ultrasonic sensing, the most widely used range is 40 to 70 kHz. The frequency determines range and resolution; the lower frequencies produce the greatest sensing range. At 58 kHz, a commonly used frequency, the measurement resolution is one centimeter (cm), and range is up to 11 meters.   4. Can ultrasonic sensor detect human? Finally, ultrasonic sensors assist in detecting people for autonomous navigation of robots. Ultrasonic sensors can be used to set multiple tripwire distances to help navigate around people. Additionally, the high read rate allows you to quickly detect when a person may enter your robot's path.   5. Is ultrasonic sensor harmful? Occupational exposure to ultrasound in excess of 120 dB may lead to hearing loss. Exposure in excess of 155 dB may produce heating effects that are harmful to the human body, and it has been calculated that exposures above 180 dB may lead to death.   6. How do ultrasonic sensors work? Ultrasonic sensors work by emitting sound waves at a frequency too high for humans to hear. They then wait for the sound to be reflected back, calculating distance based on the time required. This is similar to how radar measures the time it takes a radio wave to return after hitting an object.   7. Why is ultrasonic sensor used? Ultrasonic sensors are used primarily as proximity sensors. They can be found in automobile self-parking technology and anti-collision safety systems. ... Ultrasonic sensors are also used as level sensors to detect, monitor, and regulate liquid levels in closed containers (such as vats in chemical factories).   8. Where are ultrasonic sensors used? Ultrasonic sensors have been used throughout many applications and industries. They are used within food and beverage to measure liquid level in bottles, they can be used within manufacturing for an automated process and control maximising efficiency on the factory floor.   9. Is ultrasonic sensor waterproof? Most ultrasonic distance sensors aren't waterproof which can be a problem if you need your project to withstand the elements outdoors. ... This sensor is suitable for outdoor applications such as car reversing sensors, security alarms, industrial inspection, etc.   10. Is ultrasonic sensor analog or digital? Usually, ultrasonic sensors are integrated with an Analog-to-Digital converter (ADC).   11. How do ultrasonic sensors measure distance? As the name indicates, ultrasonic sensors measure distance by using ultrasonic waves. The sensor head emits an ultrasonic wave and receives the wave reflected back from the target. Ultrasonic Sensors measure the distance to the target by measuring the time between the emission and reception.   12. How accurate is the ultrasonic sensor? The more accurate ultrasonic sensors can achieve 0.1 – 0.2% of the detected range under perfectly controlled conditions, and most good ultrasonic sensors can generally achieve between 1% and 3% accuracy.   13. What can ultrasonic sensors detect? Ultrasonic sensors can measure the distance to a wide range of objects regardless of shape, color or surface texture. They are also able to measure an approaching or receding object.   14. Are ultrasonic sensors affected by smoke? Ultrasonic sensors are superior to infrared sensors because they aren't affected by smoke or black materials, however, soft materials which don't reflect the sonar (ultrasonic) waves very well may cause issues.   15. Which is better ultrasonic or IR sensor? Ultrasonic sensors work using sound waves, detecting obstacles is not affected by as many factors. If reliability is an important factor in your sensor selection, ultrasonic sensors are more reliable than IR sensors. If you're willing to compromise reliability for cost, infrared sensors are ideal for your application.  

Warm hints: The word in this article is about 5400 words and  reading time is about 25 minutes This article is equal to a comprehensive course about automobile sensors which including the basic introduction of automobile sensors, their types, applications, functions, and market analysis, etc.   Electronic technology has become the leading factor in the direction of the development of a new generation of automobiles, and sensors are the core components of electronic technology. More and more modern cars have used sensors more and more, in order to improve the economic, dynamic and emission performance of automobile engines, improve the braking performance, steering performance and safety performance of the vehicle. The key to achieve these goals lies in the electronic and intelligent vehicle, the prerequisite is the timely acquisition of all kinds of information, which is bound to require a large number of sensors in the car.   Catalogs I. An Overview of Automobile Sensors II. The Development History of Automobile Sensors III. Types of Automobile Sensors and Their Functions IV. Sensors Used in Automobile Engines and Their Functions 4.1 Automobile Temperature Sensor 4.2 Automobile Pressure Sensor 4.3 Air Flow Sensor 4.4 Fuel Flow Sensor 4.5 Engine Speed Sensor 4.6 Gas Concentration Sensor-oxygen Sensor V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control   System VI. Sensor Application in Automobile Safety System VII. Other Major Automotive Sensors VIII. Automotive Sensors Market Size--Its Market Trend FAQ I. An Overview of Automobile Sensors   The automobile sensor is the input device of the automobile computer system. It takes all kinds of working condition information in the car, such as speed, temperature of various medium, engine operation condition and so on, and convert it into the device or device that can be input signal according to certain law. Simply speaking, the sensor transfers the non electric quantity to the electrical signal to transmit to the ECU, so that the car is in the best working state.     An Overview of Automobile Sensors In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. Automobile sensors are responsible for the acquisition and transmission of information in these systems. The information collected by the sensors is processed by the computer (electronic control unit), and the instructions sent to the actuator are formed to complete the electronic control. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system itself according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control. Automotive sensors usually consist of three parts: sensing element, converting element, and measuring circuit.   （1）the sensitive element is the part that can be measured directly (or response), and is about to be converted into a non electric or other quantity that is determined to be determined by the sensing element of the sensor. （2）the conversion element converts the above non electric quantity into electrical parameters. （3）The function of the measurement circuit is to convert the electrical parameters input by the conversion element to the measurable quantity of voltage, current, or frequency, in order to display, record, control and handle the parts. Measurement circuit The sensor is at the interface between the research object and the test system, namely the first of detection and control. The sensor is a window to perceive, obtain and detect information. All the information obtained in the process of scientific research and automated production must be obtained by the sensor and converted into an easy transmission and processing electrical signal. Its role and status are particularly important. The following figure is the list of correspondence between the human body and machine, which helps us further understand its function.   In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. The vehicle sensors are responsible for the acquisition and transmission of information in these systems. The computer (electronic control unit ECU) sends out instructions to the actuator after the signal is processed in a hurry, and the electronic control is implemented. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control.     II. The Development History of Automobile Sensors   In the 1960s, there were only oil pressure sensors, oil sensors, and water temperature sensors on cars. They were connected with meters or indicator lights. After the 1970s, in order to control emissions, a number of sensors were added to help control the vehicle's power system, as the catalytic converters, electronic ignition, and fuel injection devices needed to maintain a certain air-fuel ratio to control emissions during the same period. Until the 1980s, ABS and airbags improved vehicle safety.   The Development History of Automobile Sensors Sensors are used today to determine the temperature and pressure of various fluids, such as intake temperature, air inlet pressure, cooling water temperature, and fuel injection pressure, and sensors used to determine the speed and position of various parts (such as speed, throttle opening, camshaft, crankshaft, angle and speed of the transmission, the position of the exhaust recirculation valve (EGR), etc.); and for measurement.   Sensors for engine load, detonation, broken fire, and oxygen content in exhaust gas; sensors to determine the seat position; sensors to determine wheel speed, road elevation difference, and tire pressure in the anti-lock braking system and suspension control device; and to protect the airbags of the front occupants, not only need more collision sensors and acceleration sensors.   The researchers also use the anti-collision sensors (ranging radar or other ranging sensors) to determine and control the lateral acceleration of the car, the instantaneous speed of each wheel and the required torque, so that the braking system is a part of the vehicle stability control system.   III. Types of Automobile Sensors and Their Functions   （1）According to the relationship of energy, sensors can be classified into two types: active and passive based on their energy relations. Most of the sensors used in cars belong to passive sensors, which require additional input power to produce electrical signals, so the sensor is actually an energy controller.    （2）According to the classification of signal conversion according to the signal conversion classification, it can be divided into one kind of non electricity conversion into another kind of non electricity, such as elastic sensitive element and pneumatic sensor; the other is the transducer converted from non electricity to electricity, such as thermocouple temperature sensor, piezoelectric accelerometer and so on.    （3）Classification according to input quantity according to input quantity is classified according to the measurement, which can be divided into displacement, velocity, acceleration, angular displacement, angular velocity, force, torque, pressure, vacuum degree, temperature, current, gas composition, concentration sensor and so on. For example, the following air flow sensor: Air flow sensor （4）According to the working principle classification according to the working principle of the sensor, there are resistance, capacitance, strain, inductance, photoelectric, photosensitive, piezoelectric, thermoelectric sensor, etc.   （5）According to the output signal classification, according to the sensor output signal, there are analog and digital sensors. Simulation system adoption and digital system adoption   IV. Sensors Used in Automobile Engines and Their Functions Electronic control of engines has been considered to be one of the main technology fields of automobiles. The sensor of engine control system is the core of the whole automobile sensor, and there are many kinds, including temperature sensor, pressure sensor, position and speed sensor, flow sensor, gas concentration sensor and detonation sensor, etc. These sensors provide the engine's work condition information to the engine's electronic control unit for accurate control of the engine working condition, in order to improve engine power, reduce fuel consumption, reduce exhaust emissions and perform fault detection. Sensors Used in Automatic Inductive Door   4.1 Automobile Temperature Sensor   Temperature sensor like automobile temperature sensor is mainly used to detect engine temperature, suction gas temperature, cooling water temperature, fuel temperature, and catalytic temperature. Water temperature state indicatior The temperature sensor has three main types: thermistor, wire wound resistor, and thermal couple resistor. These three types of sensors have their own characteristics, and their applications are also slightly different. The thermistor temperature sensor has high sensitivity and good response characteristics, but it has poor linearity and low temperature.   Among them, the universal temperature range is -50 C to 30 C, the precision is 1.5%, the response time is 10ms, the high-temperature type is 600 to 1000, the precision is 5%, the response time is 10ms; the precision of the wire-wound resistance temperature sensor is high, but the response characteristic is poor; the precision of the thermocouple resistance temperature sensor is high and the temperature range is wide, but it needs to be used together with the amplifier and cold end treatment.   Other practical products have ferric oxygen sensor (temperature range from -40 to 120, 2%), metal or semiconductor membrane air temperature sensor (temperature range from -40 to 150, 2%, 5%, response time 20ms).   4.2 Automobile Pressure Sensor The pressure sensor is the most used sensor in automobiles. It is mainly used to detect air pressure of airbags, the fluid pressure of transmission system, injection pressure, engine oil pressure, inlet pipe pressure, the fluid pressure of air filtration system, and so on. At present, the more commonly used vehicle pressure sensors are capacitive, piezoresistive, differential transformer, and surface acoustic wave.   The capacitive pressure sensor is mainly used to detect negative pressure, hydraulic pressure, and air pressure. The measurement range is 20kPa to 100kPa. Its characteristics are high input energy, good dynamic response characteristics, and good environmental adaptability.   The performance of the piezoresistive pressure sensor is affected by temperature, and it needs another temperature compensation circuit, but it is suitable for mass production; the differential transformer type pressure sensor has a large loss. The acoustic surface wave pressure sensor has the characteristics of small volume, lightweight, low power, low power, high reliability, high sensitivity, high resolution, and digital output. It can be used in the pressure detection of the automobile air suction valve and can work steadily at high temperatures.   4.3 Air Flow Sensor The flow sensor is mainly used for measuring the airflow and fuel flow of the engine. The intake volume is one of the basic parameters for fuel injection calculation. The Mass Air Flow Sensor (MAF) is a computer-controlled sensor that calculates the volume and density of the air taken in by the engine. This in turn ensures the right amount of fuel is used for optimized operating conditions. If this sensor is faulty, the car may stall and the fuel usage will be higher than necessary.   The function of the airflow sensor is to perceive the size of the airflow and transform it into an electrical signal to transmit to the electronic control unit of the engine. The measurement of airflow is used in the engine control system to determine combustion conditions, control air-fuel ratio, start, and ignition. There are 4 types of airflow sensors: rotary wing, Carmen vortex, hot wire, and hot film. The main technical indicators of the airflow sensor are: the working range is 0.11m3/min to 103m3/min, the working temperature is -40 to 120 degrees, and the accuracy is more than 1%.   4.4 Fuel Flow Sensor The fuel flow sensor is used to detect the flow rate of fuel, mainly with a water wheel and circulating ball. The dynamic range is 0 ~ 60kg/h, the working temperature is -40 to 120, the precision is 1%, and the response time is < 10ms. The position and speed sensor of position and speed sensor crankshaft and speed sensor is mainly used to detect engine crankshaft angle, engine speed, throttle opening, speed, and so on. It provides a reference point signal for ignition time and injection time and provides an engine speed signal at the same time.   4.5 Engine Speed Sensor Engine Speed Sensor is attached to the crankshaft and monitors the spinning speed of the crankshaft, which controls the fuel injection and timing of the engine.    Electromagnetic crankshaft position sensor At present, the position and speed sensors used in automobile are mainly AC generator type, magnetoresistance type, Holzer effect type, reed switch type, optical type, semiconductor magnetic transistor and so on. The measurement range is from 0 to 360 degrees, the precision is better than 0.5 degrees, and the bending angle is up to 0.1 degrees. There are many kinds of speed sensors, such as sensitive wheel rotation, sensitive power transmission shaft and sensitive differential driven shaft. When the speed of the vehicle is higher than 100km/h, the general measurement error is larger. The non contact photoelectric speed sensor should be used, the speed range is 0.5km/h to 250km/h, the repetition precision is 0.1%, and the distance measurement error is better than 0.3%.   4.6 Gas Concentration Sensor-oxygen Sensor A gas concentration sensor is mainly used to detect gas and exhaust emissions in vehicle bodies. The most important thing is the oxygen sensor. It detects the oxygen content in the exhaust gas of the car. According to the oxygen concentration in the exhaust, the air-fuel ratio is measured, and the feedback signal is sent to the microcomputer control device to control the air-fuel ratio to converge to the theoretical value.   The commonly used germanium oxide sensors (using the temperature of -40 to 900, 1%), chromium oxide concentration cell type gas sensor (using temperature 300 to 800 C), solid electrolyte chromium oxide gas sensor (using temperature 0~400, precision 0.5%), and two oxide oxygen sensor and two oxidation oxygen sensor. The Oxygen sensor measures the amount of unburdening oxygen that is present in the exhaust pipe and will indicate if the fuel is burning rich or lean. A faulty oxygen sensor will cause the car to idle poorly and jerk as well as cause high fuel consumption. Gas concentration sensor Compared with the germanium oxide sensor, the titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer. titanium dioxide oxygen sensor Among them, the stable oxidation of calcium oxide is deposited by reactive sputtering. Working electrodes and reference electrodes are made by thick film technology. The output voltage of the ideal A/F point is abrupt, the ratio of air to air is higher, the output voltage of the oxygen sensor decreases when the oxygen concentration is added in the exhaust gas; when the air-fuel ratio becomes lower and the oxygen concentration in the exhaust gas decreases, the output voltage of the oxygen sensor is increased.    The electronic control unit recognizes the mutation signal and corrections the injection volume, so as to adjust the air-fuel ratio accordingly and make it change near the ideal air-fuel ratio. At present, the NOx sensor is more and more strict for the diesel exhaust emission of NOx and PM. To cope with this limitation, it is not enough to improve the combustion mode of diesel engines. Therefore, post-processing technology is more and more valued. The selective reduction catalyst (SCR) method is one of the NOx purification techniques. The NOx in the tail gas can be selectively adsorbed to the catalyst. By spraying urea to the catalyst, the NOx can be decomposed into nitrogen, water, and discharge by reduction reaction.    The sensor in urea SCR can detect whether the dosage of urea water needed for SCR is suitable. This sensor is essential for reducing agents using nitrogen oxides (NOx) as urea water purifiers. Knock sensor detonation sensor is used to detect engine vibration, by adjusting ignition advance angle and avoiding detonation. Detonation can be detected in three ways, namely cylinder pressure detection, engine block vibration, and combustion noise.    The detonation sensors have magnetostrictive and piezoelectricity. The use temperature of the magnetostrictive detonation sensor is -40 C ~125 C and the frequency range is 5~10kHz; the piezoelectric detonation sensor has a sensitivity of 200mV/g at the center frequency 5.417kHz and has good linearity in the range of 0.1g~10g. titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer.     V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control  System   Chassis sensors are sensors distributed in the transmission control system, the suspension control system, the power steering system, and the braking system. They are different in different systems, but the working principle is the same as the sensor in the engine, which is mainly used in the following.   Suspension sensors are used to control and control vehicle dynamics by interfering and adjusting the characteristics of vehicle suspension components. The continuous damping control system (ADC) consists of 4 control units, CAN, 4 wheel vertical acceleration sensors, 4 body vertical acceleration sensors, and 4 damper proportional valves.    According to the vehicle movement and the information detected by these sensors, the optimal damping coefficient of each wheel suspension damper is calculated, the height of the car is adjusted automatically, the change of the vehicle posture is suppressed, and the control of vehicle comfort, handling stability and driving stability is realized. The system is realized by the electronic control of the steering angle of the wheel.    The common system has the active front-wheel power steering system ESP, the active front-wheel superposition steering system AFS, and the active rear-wheel steering system RWS. The sensors used mainly include the speed sensor, engine speed sensor, torque sensor, and so on, which make use of these sensors to make the power steering control system realize steering control light, improve response characteristic, reduce engine loss, increase output power, save fuel and so on.   Whether it is ESP, AFS, or RWS, the principle of it is the driver's manipulation instruction, which senses the condition of the road surface by the sensor, and passes the network to the electronic controller and the actuator in the form of the electrical signal.   （1）The anti-lock braking sensor of the ABS system mainly uses the wheel angular velocity sensor to detect wheel speed. When the slip rate of each wheel is 20%, the brake oil pressure is controlled, the braking performance is improved, and the vehicle handling and stability are ensured. In this system, the wheel speed sensor is a very important part of ABS. It needs to provide reliable and precise wheel speed to ECU in time. The sensors have electromagnetic, Holzer, and magnetoresistance.   （2）TCS system, when the driving torque of the vehicle driving wheel is too large, the driving wheel will move relative to the ground. It is generally hoped that the slip rate of the driving wheel should not exceed 20%. This system of control for driving wheel skating is called the TCS system. It is developed on the basis of ABS. In most cars, TCS and ABS share an ECU. They identify and judge the driving condition of a vehicle based on the signal input by sensors.   （3）ESP electronic stabilization system ESP is an active safety system with good maneuverability and direction stability by adjusting the size and matching of the longitudinal force of the wheel to control the yaw motion of the car. The basic principle of ESP is to identify the expected motion state of a driver by means of sensors and operational logic. In order to identify the driver's expectation of the car and know the actual motion state of the car, the ESP system needs more sensors than ABS and TCS. They are hydraulic sensors of steering wheel sensor, vehicle yaw rate sensor, lateral acceleration sensor, and brake master cylinder.     VI. Sensor Application in Automobile Safety System   Safety is the primary factor for automobile consideration, and there are many sensors for safety, such as micro accelerometers for automobile airbags, surface micromachined gyroscopes of angle measurement rate, etc. Microaccelerometer micro accelerometer is usually composed of a parallel cantilever beam, one end of the beam is fixed on the frame and a small mass block (about 10mg) is suspended at the other end.    When there is no acceleration, the mass block is not moving. When there is a vertical acceleration, the mass block is moving, the acceleration is sensitive to the acceleration, and the signal is converted to the output by C/V transformation and phase-sensitive demodulation. According to the detection mode, the micro accelerometer has several kinds of piezoresistive, capacitive, tunnel, resonant, and thermal forms.   The capacitance micro accelerometer has high sensitivity, low noise, small drift and a simple structure. It is widely used in automobile airbag systems and anti-skid systems. The mass of capacitance micro accelerometer mass block moves downward when it has acceleration and changes the distance from another electrode on the frame. The displacement of mass movement can be obtained by measuring the change of capacitance.    The main structure is divided into suspension. The arm swing type and comb-like folded beam type are changed into other types. The structure of the former is relatively simple, and the bulk silicon processing method is mostly used. The simple pendulum type structure consists of the upper and lower fixed electrodes and the movable sensitive silicon cantilever beam electrode, the anisotropic corrosion of the semiconductor plane process, and the encapsulation of the electrostatic sealing technology. The latter can be regarded as the combination of the cantilever beam and the combination.    The design is much more complicated. The micromachining method is mainly based on surface sacrificial layer technology. The isotropic properties of the polysilicon material can guarantee the symmetry of the micromechanical properties, the precision of the batch processing is high, and the sensitive parts of this structure are small in size, and the monolithic integration of the peripheral circuits is realized. Micromachined gyroscope (MEMS) micromachined gyroscope (MEMS) is a vibrational angular rate sensor, which has attracted much attention in the application and development of automobiles. It is mainly used in GPS signal compensation and chassis control system for automobile navigation.   There are two vibration modes in the micromechanical gyroscope, one is the transverse vibration mode, that is, the mode of driving vibration, which is usually called the reference vibration, which will produce additional motion under the action of the Coriolis force; the other is the normal vibration mode, the sensitive vibration mode, the detection of the additional movement of the Coriolis force, and the angular rate information contained in the Coriolis force. According to the material used, the micromachined gyroscope is divided into two kinds of quartz and silicon vibrating beams. The quality factor of quartz material has the highest Q value, the top characteristic of the gyroscope is the best, but the quartz processing is difficult and the cost is very high.    Silicon material has complete structure, good elasticity, and easy to get high Q value micromechanical structure, which has become the mainstream of low-cost research and development at present. The structure of the silicon micromachined gyroscope, the vibration beam structure, the double frame structure, the plane-symmetric structure, the transverse fork structure, the comb tuning fork structure, the beam island structure are used. The driving modes for the reference vibration are electrostatic, piezoelectric, and electromagnetic driving. The detection methods of additional vibration caused by the Coriolis force are capacitive detection, piezo detection, and piezoresistive. Testing.    The gyroscope design with electrostatic drive and capacitance detection are the most common. Some of the products have been developed successfully. Vehicle monitoring and self-diagnosis sensor in-vehicle monitoring and self-diagnosis, the main application of vehicle sensors will be tire pressure monitoring, followed by sensors applied to cooling, braking, and other systems.    In addition, such as the use of light sensors in the luminance control system, the use of magnetic sensors and airflow velocity sensors in the driving system, the use of indoor temperature sensors, suction temperature sensors, air volume sensors, sunshine sensors, and humidity sensors in the automatic air conditioning system, and the use of azimuth sensors and speed sensors in the steering system.    The collision sensor is the main control signal input device in the airbag system. The effect is when the vehicle collides on the road, the collision sensor is used to detect the intensity signal of the car collision, and the signal is entered into the airbag computer. The airbag computer determines whether the inflatable element is detonated to inflate the airbag according to the signal of the collision sensor. After the transformation of many countries, many cars are also equipped with side airbags. When the car has a lateral collision, the airbag will also be inflated, so a system equipped with a lateral airbag is equipped with a collision sensor on the left and right sides of the car.    This is more humane in ensuring the safety of vehicle users. The lateral tilt angle sensor is an effective method to prevent the car from turning over the car during driving. It is an important measure to improve the safety of the car, especially the high gravity cars, such as the off-road vehicle and the double-deck passenger car, which is more necessary.   Take an example, an angle sensor made with the principle of gravity. The mass of the swing part is m, and the distance between the center of gravity and the shaft is L. When the car body tilts or curves, it can make the swing part deflect. The force analysis in Figure 1 is an ideal state without any friction. The force F is the result of the joint action of the sliding force F1 and the centripetal force F2. The force F is proportional to the tilting force, and the beta-generated deflection angle is proportional to the tilting force. The resultant force T of the gravitational G and F in the oscillating part is the tension of the pendulum, and the swing angle of beta =tg-1 (F/G) is independent of L. When the mass m is fixed, the beta is only related to F and is proportional.   In fact, due to the existence of friction on the shaft, the longer the L is, the larger the swing torque is, the higher the accuracy. Angle sensor is usually used as a sampling element in the control system, and its performance plays an important role in the whole system. The potentiometer angle sensor has been widely used in all kinds of control systems, but its disadvantage is the existence of sliding wear and electrical noise of the contact. The magnetic sensitive resistance angle sensor is a new pure resistive element made of semiconductor technology. It is characterized by no contact.    When the swing partial deflection, the flux of the magnetic resistor is changed to make the resistance of the magnetic sensitive resistance several times. The above changes fundamentally eliminate the electrical noise and improve the accuracy. All kinds of angle sensors have a damping function so that there is a short delay in response to the measured angle, which is beneficial for the control system.   VII. Other Major Automotive Sensors   Alcohol detection MEMS system is a new type of integrated alcohol sensor, which can adsorb oxygen according to the oxygen concentration in the environment and change the resistance value. In normal conditions, the element can keep a certain resistance value after the oxygen is adsorbed in the air, and once the air contains alcohol, the oxygen element on the surface of the element will react with the alcohol to reduce the resistance value.    By measuring the resistance value, we can detect the alcohol concentration in the breath. The alcohol detection MEMS sensor will be embedded in the sealed shell of the diameter 8mm, together with the signal processing circuit and so on, and will be embedded in the steering wheel together. Once the driver's exhaled gas contains alcohol, a safety alarm will be issued.    When the raindrop is hit on the glass of the induction zone, the intensity of the light reflected by the raindrop will change because of the rainfall or moisture content on the glass and changes the brushing frequency of the wiper. Or through the infrared electronic rainfall sensor to induce the amount of rainfall, and automatically adjust the speed of the wiper with the change of speed to improve the driver's driving convenience to make the driving safer.    The tire pressure monitoring system installs highly sensitive sensors on each tire to monitor the tire condition at any time in the driving state and transmit it wireless to the receiver through a sensor to enable the driver to grasp the condition of the tire at any time, to ensure the safety of the car, to prolong the service life of the tire and to reduce the consumption of the fuel. The most advanced direct tire pressure monitoring solutions include advanced warning systems, pressure, temperature, voltage and motion detection.   When the oil viscosity sensor changes the oil, it usually depends on the time or mileage specified by the manufacturer. A few manufacturers have adopted a more advanced way to calculate the oil exchange interval by recording engine speed and temperature.     VIII. Automotive Sensors Market Size--Its Market Trend   Because of the important role of automotive sensors in the automotive electronic control system and the rapid growth of the market demand, all countries in the world have paid great attention to its theoretical research, new material application, and new product development. The development trend of automotive sensor technology in the future is miniaturization, multi-function, integration, and intelligence.   The microsensor with low cost and high performance can be designed by means of micro electro mechanical system (MEMS) technology and computer-aided design technology. At the current level of technology, micromachining technology has been able to produce microstructures with different levels of 3D, and then produce tiny sensor sensors with very small sizes. Because the components are relatively small, the use is relatively convenient and efficient, making the economy improved.    Multifunction means that a sensor can detect 2 or more two characteristic parameters or chemical parameters, thus reducing the number of sensors and improving the reliability of the system. Integration refers to the use of IC manufacturing technology and fine processing technology to make IC sensors. Intelligentization refers to the combination of sensors and large-scale integrated circuits with CPU, which is intelligent, to reduce the complexity of ECU, to reduce its volume, and to reduce the cost.    In addition, the development of new materials is an important basis for sensor technology. Now new materials, such as optical fiber, nanomaterials, superconducting materials, have opened a new world for the development of sensors. With the development of research, more and more new sensor materials will be developed. The function of the sensor is not only related to its material, but also to its processing technology.    Micromachining technology has been increasingly used in the sensor manufacturing process. With the development of modern manufacturing technology, more advanced manufacturing technologies will be applied to the manufacture of automotive sensors. The principle of the sensor is based on various physical, chemical, biological effects, and laws, which enlightens people to further explore sensitive functional materials with new effects and to develop new sensors with new principles. This is an important way to develop low-cost, high-performance, multi-functional, and miniaturized sensors. FAQ   1. What is a sensor in automobile? Automobile sensors are intelligent sensors which can be used to control and process the pressure of oil, temperature, level of emission, coolant levels, etc. There are different types of sensors used in automobiles, but knowing the working of these sensors is essential.   2. How many sensors does a car have? Currently, each vehicle has from 60 to 100 sensors on board and we can expect that number to rise as cars get 'smarter'.” In fact, recent industry figures suggest the number of sensors is projected to reach as many as 200 per car based on current trends.   3. What is the importance of sensors in the automobile? Sensors monitor vehicle engines, fuel consumption and emissions, along with aiding and protecting drivers and passengers. These allow car manufacturers to launch cars that are safer, more fuel efficient and comfortable to drive.   4. How do vehicle sensors work? Using echo-times from sound waves that bounce off nearby objects, the sensors can identify how far away the vehicle is from said object, and alert the driver the closer the vehicle gets. Electromagnetic sensors create an electromagnetic field around the bumper, and offer an alert whenever objects enter it.   5. How many sensors does a F1 car have? 300 sensors. With help from over 300 sensors on each car, McLaren's F1 ECU deals with over 1000 input parameters and transmits more than 1.5GB of live data back to the garage during an average 300km grand prix.   6. Where are sensors located on cars? Depending on the vehicle engine model, you often have 1 to 4 exhaust gas temperature sensors. The sensors are installed on the exhaust pipe and the exhaust manifold, and sometimes also on the turbocharger. The sensors are often quite expensive and can be difficult to reach and replace; they often rust and get stuck.   7. How long do car sensors last? Newer oxygen sensors are supposed to work efficiently for 60,000 to 90,000 miles, depending on the model of your car. If your mechanic determines that your car's problem is due to a bad or failing oxygen sensor, the replacement shouldn't take long and you'll be ready to tackle many more miles on the road.   8. Do all cars have sensors? Modern cars have an increasing amount of sensors. Most cars have an oxygen sensor and a throttle position sensor, but parking sensors are optional. Professional mechanics agree that one of the most important evolutions to come about in recent years is the expansion of sensors to monitor mechanical systems.   9. How do I know if my upstream or downstream oxygen sensor is bad? A decrease in fuel efficiency can be a telltale sign that an O2 sensor is not performing as it should. This can happen because of a fuel mixture that is either too lean or too rich. Such a swing in A/F ratio is a sign that an upstream or control sensor is faulty.   10. What does a car do when the oxygen sensor is bad? If your oxygen sensor is failing, then its readings will be inaccurate, again, resulting in a sub-optimal fuel-to-air composition. Your car's performance isn't the only thing that is harmed by a malfunctioning oxygen sensor - it can do damage to the environment as your car's emissions will increase drastically.  

Warm hints: this article reading time is about 15 minutes. This article is mainly about learning several kinds of industrial weapons - sensors. Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, systems engineering, computer technology, electronics, hydraulic pressure technology, and automatic control, among which automation is based on control theory and computer technology.   CatalogI、Automation TechnologyII、Physical SensorIII、Fiber Optic SensorIV、Bionic SensorV、Infrared SensorVI、Electromagnetic SensorVII、Magneto-optical Effect SensorVIII、How to Choose Industrial SensorsFAQ I. Automation Technology Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, system engineering, computer technology, electronics, hydraulic pressure technology, automatic control, etc., of which automation and control theory and computer technology The most influential technology. There are a lot of special equipment in automation technology, just like the different weapons, the author made a count of the automated weapons below.II. Physical SensorPhysical sensorSensor (Sensor) is a common but very important device. A sensor is a device, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. For the sensor, the input can be divided into static and dynamic according to the input state. We can get the static characteristics of the sensor based on the relationship between the output and the input based on the steady-state of each value.  The main indicators of the static characteristics of the sensor are linearity, hysteresis, repeatability, sensitivity, and accuracy. The dynamic characteristics of a sensor refer to the response characteristics of the input over time. Dynamic characteristics are usually described using automatically controlled models such as transfer functions. In general, the signal received by the sensor has a weak low-frequency signal, and the amplitude of the external interference sometimes exceeds the measured signal. Therefore, eliminating the noise in series becomes a key sensor technology. The physical sensor is a sensor that detects physical quantities by the use of certain physical effects. The sensor can convert measured physical volume into a form of energy to facilitate the processing of the signal device. The output signal and the input signal have a definite relationship. The main physical sensors include photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, pyroelectric sensors, and optical fiber sensors.  As an example, let us look at the more commonly used photoelectric sensors. This kind of sensor converts the optical signal into an electrical signal. It directly detects the radiation information from the object and can also convert other physical quantities into an optical signal. The main principle is the photoelectric effect: When the light is irradiated to the material, the electrical effect on the material changes, and the electrical effects here include electron emission, conductivity, and potential current. Obviously, a device that can easily produce such an effect becomes a major component of a photoelectric sensor, such as a photoresistor.  In this way, we know that the main working process of a photoelectric sensor is to receive the corresponding light, convert the light energy into electricity through a device such as a photosensitive resistance, and then obtain the required output by amplification and denoising electric signal. The output electrical signal here has a certain relationship with the original optical signal, which is usually close to a linear relationship so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be compared to optical sensors. The range of applications of physical sensors is very extensive. We look at the application of physical sensors from the perspective of biomedical sciences. It is not difficult to infer that physical sensors have important applications in other aspects. For example, blood pressure measurement is the most common type of medical measurement. Our usual blood pressure measurement is an indirect measure of the blood pressure in the vessel by measuring the relationship between blood flow and pressure detected by the body surface. The sensors needed to measure blood pressure usually include an elastic diaphragm that transforms the pressure signal into a deformation of the diaphragm and then converts it into a corresponding electrical signal based on the strain or displacement of the diaphragm. At the peak of the electrical signal, we can detect systolic pressure. After passing through the inverter and the peak detector, we can get the diastolic pressure. The average pressure can be obtained through the integrator. Let us look again at breath measurement technology. Respiratory measurement is an important basis for the clinical diagnosis of lung function and is essential in surgery and patient monitoring. For example, when using a thermistor sensor for measuring respiratory rate, mount the sensor's resistance on the outside of the front end of a clip, clip the clip over the nose, and pass the heat as the flow of breathing gas flows from the thermistor surface Sensitive resistance to measure the frequency of breathing and the status of hot gas. Another example of the most common body surface temperature measurement process. Although it seems easy, it has a complex measurement mechanism. The body surface temperature is determined by various factors such as the local blood flow, the heat conduction of the underlying tissue, and the heat dissipation of the epidermis. Therefore, the measurement of the skin temperature must take into account various influences.  Thermocouple sensors are more commonly used in the measurement of temperature, usually rod-shaped thermocouple sensors and thin-film thermocouple sensors. Because the size of the thermocouple is very small and the accuracy is relatively high, it is possible to measure the temperature at a certain point accurately. With the help of later analysis statistics, a more comprehensive analysis result can be obtained. This is incomparable with the traditional mercury thermometer, but also shows the broad prospects for the application of new technologies to scientific development. From the above introduction, it can be seen that physical sensors have a variety of applications just in biomedical applications. The development direction of the sensor is a multifunctional, imaged, intelligent sensor. Sensor measurement as an important means of data acquisition is indispensable for industrial production and even family life, and physical sensors are the most common family of sensors. The flexible use of physical sensors will inevitably create more products and better benefits. III. Fiber Optic SensorFiber optic sensorIn recent years, sensors have evolved in the direction of sensitivity, precision, adaptability, compactness, and intelligence. In the process, fiber optic sensors are a new addition to the sensor family. Optical fiber has many excellent properties, such as anti-electromagnetic interference and atomic radiation performance, fine diameter, soft, lightweight mechanical properties, insulation, non-inductive electrical properties, water resistance, high-temperature resistance, corrosion resistance, chemical properties, etc. It can reach people's eyes and ears in unattainable places (such as high-temperature areas), or in areas harmful to humans (such as nuclear radiation area), but also can transcend human physiological boundaries and receive sensory organs Unforeseen outside information. Optical fiber sensors are new technologies that have emerged in recent years. It can be used to measure a variety of physical quantities, such as sound fields, electric fields, pressures, temperatures, angular velocities, and accelerations, as well as measurement tasks that are difficult to accomplish with existing measurement techniques. In tight spaces, fiber optic sensors show unique capabilities in environments with strong electromagnetic interference and high voltage. At present, there are more than 70 optical fiber sensors, which are roughly divided into optical fiber sensors and optical fiber sensors. The so-called optical fiber sensor itself is the optical fiber directly to receive the outside world was measured. The external measured physical quantity can cause the length, refractive index, and diameter of the measuring arm to change so that the light transmitted within the fiber changes in amplitude, phase, frequency, polarization, and the like. The light transmitted by the measuring arm interferes (compares) with the reference light of the reference arm to change the phase (or amplitude) of the output light, and the change in the measured light can be detected based on this change. The phase of the transmission in the optical fiber is highly sensitive to external influences, and the interferometric technique can detect the physical quantity corresponding to the slight phase change of 10 negative quadratic arcs. For the optical fiber’s winding and low loss characteristics, we can disc a long fiber optic into a small diameter optical fiber ring in order to increase the length, to obtain higher sensitivity. An optical fiber acoustic sensor is a kind of sensor using the optical fiber itself. When the fiber is a little tiny external force, it will produce micro-bending, and its light transmission capacity has undergone great changes. Sound is a kind of mechanical wave. Its effect on the optical fiber is to stress and bend the optical fiber. By bending, the sound intensity can be obtained. Compared with laser gyro, FOG has high sensitivity, small size, and low cost. It can be used in the high-performance inertial navigation systems of aircraft, ships, and missiles. Another major category of fiber optic sensors is the use of fiber optic sensors. The structure is rough as follows: The sensor is located at the end of the fiber. The fiber is just the transmission line of light, and the physical quantity to be measured is transformed into the change of the amplitude, phase, or amplitude of the light. In this sensor system, conventional sensors are combined with optical fibers. The introduction of optical fibers offers the possibility of implementing probing telemetry. This fiber-optic transmission sensor has a wide range of applications and is easy to use, but its accuracy is slightly lower than that of the first type of sensor. Fiber optic sensors have become a rising star in sensor families with their numerous advantages and have played their own unique role in various measurements and become an indispensable part of the sensor family. IV. Bionic SensorBionic sensorA bionic sensor is a new sensor using a new detection principle, which uses immobilized cells, enzymes, or other bioactive substances and transducers to form a sensor. This kind of sensor is a new type of information technology developed in recent years by the mutual penetration of biomedicine and electronics and engineering. This sensor is characterized by high performance and long life. In bionic sensors, biometric sensors are more commonly used. Bionic sensors in accordance with the media used can be divided into enzyme sensors, microbial sensors, organelle sensors, tissue sensors. In the picture, we can see that there is a close connection between the biomimetic sensor and all aspects of the biological theory and it is a direct result of the development of the biological theory. Among biosensors, urea sensors are a recently developed type of sensor. The following is an example of a urea sensor biosensor sensor application. The urea sensor is mainly composed of two parts, a biofilm, and an ion channel. The biofilm can feel the effects of external stimuli, the ion channel can receive the information of the biofilm and amplify and deliver it. When the sensory site inside the film is affected by an external stimulating substance, the permeability of the membrane will change, allowing a large number of ions to flow into the cell to form the transmission of information. Among them, the important component of the biofilm is the membrane protein, which can produce a conformal network change, change the permeability of the membrane, and transmit and amplify the information. The biofilm ion channels, which are composed of amino acid polymers, can be replaced by polymers of polyamine acids (L-glutamic acid, PLG), which are easily synthesized in organic chemistry, and are more chemically stable than the enzyme. PLG is water-soluble, which is not suitable for motor modification. However, PLG and polymer can synthesize block copolymers to form sensor films for sensors. The principle of the ion channel of the biofilm is basically the same as that of the biofilm. After the block copolymer film is fixed on the electrode, if a substance that changes the inductive network of the PLG is added, the permeability of the film changes, and thus a current is generated. Changes in the current from the changes can be carried out on the detection of stimulating substances. The urea sensor has been tested and proved to be a biometric analog sensor with good stability. The lower limit of detection is 10 orders of magnitude of a negative third power. It can also detect irritant substances, but for the time being it is not suitable for the measurement of living organisms. At present, although many biomimetic sensors have been developed successfully, the stability, reproducibility, and mass productivity of biomimetic sensors are obviously insufficient. Therefore, biomimetic sensing technology is still in its infancy. Therefore, in addition to continuing to develop a new series of biomimetic sensors And improve the existing series, the biomembrane immobilization technology and solid-state biomimetic sensor deserved further study. In the near future, biomimetic sensors that simulate the functions of the organism will appear, which may exceed the sensitivity of human facial features and improve the robot's vision, taste, touch, and ability to operate on objects. We can see the broad prospects for biomimetic sensor applications, but these require the further development of biotechnology, and we'll see this day coming. V. Infrared SensorInfrared sensorInfrared technology has been developed to the present, as we all know. This technology has been widely used in modern science and technology, national defense and agriculture, and other fields. Infrared sensing systems are infrared-based measurement systems that can be divided into five categories based on function:  (1) radiometers for radiation and spectroscopic measurements; (2) search and tracking systems for searching and tracking infrared targets, determining Its spatial position and its movement are tracked; (3) The thermal imaging system can produce a distribution image of the entire target infrared radiation; (4) Infrared ranging and communication systems; (5) Hybrid systems, refer to the above categories A combination of two or more in the system. Let us look at the composition of the infrared system, the main optical system, and auxiliary optical system, on the basis of which the key components of infrared are discussed in detail. In fact, the working principle of the infrared sensor is not complicated, the working principle of each part of a typical sensor system is as follows: (1)The target object. According to the infrared radiation characteristics of the target to be set, the infrared system can be set. (2)Atmospheric attenuation. When the target's infrared radiation passes through the Earth's atmosphere, the infrared radiation emitted by the infrared source will be attenuated due to the scattering and absorption of gas molecules and various gases, and various sol particles. (3) Optical receiver. It receives a portion of the target's infrared radiation and transmits it to the infrared sensor. Equivalent to a radar antenna, often used as an objective lens. (4) Radiation modulator. Radiation from the target under test is modulated into alternating radiant light to provide the target orientation information and to filter out large areas of interfering signals. Also known as a reticle and chopper, it has a variety of structures. (5) Infrared detector. This is the heart of the infrared system. It is the use of infrared radiation and the physical interaction between the physical effects of detecting infrared radiation sensors, in most cases is the use of this interaction presented by the electrical effects. Such detectors can be divided into two types of photon detectors and thermal detectors. (6) Detector cooler. Since some detectors must work at low temperatures, the corresponding system must have refrigeration equipment. After cooling, the equipment can shorten the response time and increase detection sensitivity. (7) Signal processing system. The detected signal is amplified, filtered, and extracted from these signals. This information is then converted into the required format and finally delivered to the control device or display. (8) Display device. This is the terminal device of the infrared device. Commonly used displays include oscilloscopes, kinescopes, infrared sensitized materials, indicating instruments, and recorders. Here gives a video of infrared sensors:Working principle of infrared sensorAccording to the above process, the infrared system can complete the measurement of the corresponding physical quantity. The infrared system is the core of infrared detectors, according to the detection mechanism of different, can be divided into two categories of heat detectors and photon detectors. The heat detector is used as an example to analyze the principle of the detector. The thermal detector is the use of radiant heat effect, so that the detection element causes the temperature to rise after receiving radiation, and thus makes the detector temperature-dependent performance changes. By detecting a change in one of these properties, radiation can be detected. In most cases, radiation is detected by thermoelectric changes. When the element receives the radiation and causes a non-electrical physical change, the corresponding change in the amount of electricity can be measured by appropriate transformation. Infrared sensors have played an important role in modern production practices. With the improvement of detection equipment and other parts of technology, infrared sensors can have more performance and better sensitivity. VI. Electromagnetic Sensor Magnetic sensors are the oldest sensors and compass is the earliest application of magnetic sensors. However, as a modern sensor, in order to facilitate the signal processing, a magnetic sensor is required to convert the magnetic signal into an electrical signal. The earliest applications were magnetoelectric sensors manufactured on the principle of electromagnetic induction. This magnetic sensor has made an outstanding contribution to industrial control. But today it has been replaced by a new type of magnetic sensor based mainly on high-performance magnetically sensitive materials.The shape of an electromagnetic sensorAmong the electromagnetic effect sensors used today, the magnetic rotation sensor is an important one. Magnetic rotation sensor mainly by the semiconductor magnetoresistive components, permanent magnets, fixtures, enclosures, and other components. A typical structure is a pair of magnetoresistive elements mounted on a permanent magnet stimulation, the input and output terminals connected to the fixture, and then installed in the metal box, and then sealed with plastic to form a closed structure, the structure has good reliability. Magnetic rotation sensor has many advantages of semiconductor magnetoresistance element. In addition to having high sensitivity and a large output signal, it also has a strong speed detection range, which is due to the development of electronic technology. In addition, this sensor can also be used in a wide temperature range, has a long working life, resistance to dust, water, and oil, and therefore withstand a variety of environmental conditions and external noise. Therefore, this kind of sensor has received widespread attention in industrial applications. Magnetic rotary sensors are widely used in factory automation systems because they have satisfactory characteristics and do not require maintenance. Its main application is the machine tool servo motor rotation detection, factory automation robotic arm positioning, hydraulic stroke detection, factory automation related equipment position detection, rotary encoder detection unit, and a variety of rotating detection unit. Modern magnetic rotation sensors mainly include four-phase sensors and single-phase sensors. In the course of work, four-phase differential rotation sensor with a pair of detection unit to achieve differential detection, the other to achieve the inverted differential detection. In this way, four-phase sensor detection capability is four times single-element. The two-element single-phase rotation sensor also has its own advantages, that is, small and reliable features, and the output signal can detect low-speed movement, anti-environmental impact, and anti-noise ability, low cost. Therefore, single-phase sensors will also have a good market. Magnetic rotary sensors also have great potential for use in household appliances. In the reversing mechanism of the cassette recorder, a magnetic resistance element can be used to detect the end of the magnetic tape. Most home video recorders have a variable speed and high-speed playback function, which can also be used magnetic spindle sensors to detect the spindle speed and control, to obtain a high picture quality. The positive and negative rotation of the motor in the washing machine and the high and low-speed rotation functions can be detected and controlled by the servo rotation sensor. Electromagnetic proximity switch. This switch can be sensed into the metal area of their own test objects, control their own internal circuit on or off. The switch generates its own magnetic field. When a metal object enters the magnetic field, it will cause a change in the magnetic field. This change can be turned into an electrical signal by switching the internal circuitry. The electromagnetic sensor is a widely used high-tech, both at home and abroad have invested some research efforts in research, the application of this sensor is penetrating into the national economy, national defense construction and people's daily life in all fields, with the information The arrival of society, its status and role will certainly be more prominent. VII. Magneto-optical Effect SensorMagneto-optical effect sensorModern electric measurement technology is maturing day by day, has the advantages of high precision, easy to real-time processing connected to a microcomputer, etc., has been widely used in the measurement of electrical and non-electrical measurements. However, the electrical measurement method is susceptible to interference. In the AC measurement, the frequency response is not wide enough and there are certain requirements on voltage and insulation. With the rapid development of laser technology, the above problems have been solved. Magneto-optic effect sensors are high-performance sensors using laser technology. Laser is another new technology that has been rapidly developed in the early 1960s. Its appearance signals that people have mastered and utilized light waves and entered a new stage. Due to the low monochromaticity of ordinary light sources in the past, many important applications are limited. The advent of lasers makes radio technology and optical technology by leaps and bounds, penetrate each other and complement each other. Today, many sensors have been fabricated using lasers that solve many of the unsolved technical problems that make them suitable for use in hazardous, flammable places such as coal, oil, and gas storage. For example, optical fiber sensors made of laser can measure the situation of crude oil injection, cracking oil tank parameters. It is not necessary to supply power at the place of measurement. This is particularly applicable to the petrochemical equipment group that requires strict safety and explosion protection measures. It can also be used to implement optical method telemetry chemistry in some aspects of large-scale steel plants. The principle of magneto-optic effect sensor mainly utilizes the polarization state of light to realize the function of the sensor. When a beam of polarized light passes through the medium, if there is an external magnetic field in the beam propagation direction, the light will rotate through the plane of polarization by an angle, which is the magneto-optical effect. That is, the applied magnetic field can be measured by the angle of rotation. Under certain experimental setups, the angle of deflection is proportional to the intensity of the output, and the laser diode LD is illuminated by the output light to obtain the digitized light intensity that is used to measure a particular physical quantity.Magneto-optical effect sensorSince the late 1960s, RC Lecraw has raised great concerns after his research report on magneto-optical effects was presented. Japan, the Soviet Union, and other countries have conducted research, and domestic scholars have also explored it. Magneto-optical sensor with excellent electrical insulation properties and anti-interference, wide frequency response, safety, and explosion-proof and other characteristics, and therefore for some special occasions electromagnetic parameters of measurement, has a unique effect, especially in the power system high voltage and current The measurement aspect shows its potential advantages. At the same time, by developing the software and hardware of the processing system, automatic real-time measurement of the welding machine and the robot control system can also be realized. In the use of magneto-optic effect sensors, the most important thing is to choose magneto-optical media and lasers. Different devices have different capabilities in terms of sensitivity and working range. With the advent of high-performance lasers and new types of magneto-optical media in recent decades, the performance of magneto-optical effect sensors has become stronger and the applications have become more widespread. Magneto-optical sensor, as a specific purpose sensor, can play its own function in a particular environment. It is also a very important industrial sensor.  VIII. How to Choose Industrial SensorsModern sensors vary widely in principle and structure. How to select a sensor based on a specific measurement purpose, measurement object, and measurement environment is the first problem to be solved when performing a certain amount of measurement. When the sensor is determined, the matching measuring method and measuring equipment can be determined. The success or failure of measurement results depends to a large extent on the reasonableness of the choice of sensors. The influencing factors are:  (1) Determine the type of the sensor according to the measurement object and the measurement environment. (2)Selection of the sensitivity. (3)Frequency response. (4) Linear range. (5)Stability.(6) Accuracy. FAQ 1. 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. You May Also Like GPS and inertial sensors for driverless applicationsA New Technology for Advancing Opticals,Sensors Even Resistant SupercapacitorsSensors are Always In a State of Rapid ProgressComprehensive Analysis of Fiber Optic Sensor 

Warm hints: The word in this article is about 2500 and  reading time is about 12 minutes. The fiber optic sensor consists of the light source, incident fiber, exit fiber, light modulator, light detector, and demodulator. The basic principle is that the light of the light source is sent to the modulation area through the incident optical fiber, and the light interacts with the measured parameters in the modulation area to change the optical property of the light into the modulated signal light which is then sent through the outgoing fiber optical detector, demodulator and get the measured parameters. In recent years, sensors have evolved in the direction of sensitivity, precision, adaptability, compactness, and intelligence.  Optical fiber has many excellent properties, such as anti-electromagnetic interference and atomic radiation performance, soft and lightweight mechanical properties. Insulation, non-responsive electrical properties. Water, heat, and corrosion resistance of chemical properties, can reach people's eyes and ears in unattainable places (such as high-temperature areas), or in areas harmful to humans (such as nuclear radiation area), but also can transcend human physiological boundaries and receive sensory organs Unexpected outside information.   Catalogs I. Basic Structure and Principle of Fiber Optic SensorII. Application of Light Sensor in Petrochemical Industry2.1 The application of fiber optic sensor in the   petrochemical system2.2 The application of fiber optic sensor in oil   loggingIII. Application of Fiber Optic Sensors in Power Systems3.1 Applications in the high voltage cable temperature   and strain measurement3.2 Application in Electric Power Sensors3.3 Application of optical fiber cable monitoringIV. Fiber Optic Sensors in Medical Applications4.1 Pressure measurement4.2 Blood flow velocity measurement4.3 PH measurementV. Fiber Optic Sensor FeaturesFAQ  I. Basic Structure and Principle of Fiber Optic Sensor The fiber optic sensor consists of the light source, incident fiber, exit fiber, light modulator, light detector, and demodulator. The basic principle is that the light of the light source is sent to the modulation area via the incident fiber, and the light interacts with the measured parameters in the modulation area to make the optical properties (such as intensity, wavelength, frequency, phase, and normality) of the light occur Changes into a modulated signal light, and then sent through the optical fiber into the optical detector, demodulator to obtain the measured parameters. Fiber optic sensors can be divided into two categories by sensing principle: one is the light transmission (non-functional type) sensor, the other is the sensor type (functional) sensor. In the fiber optic sensor, the optical fiber only as a light transmission medium, the measured signal is detected by other sensitive components, this exit fiber, and the incident optical fiber is not continuous. Between the two Modulators are spectrally sensitive or other types of sensitive elements. In the sensing type fiber optic sensor, the optical fiber has both the sensitivity to the signal to be measured and the transmission of the optical signal. And the "sense" and "pass" of the signal are combined so that the optical fiber in such a sensor is continuous. Due to the different roles played by the optical fibers in these two sensors, the requirements for the optical fibers are also different. Optical fiber in the light-transmitting sensor only plays the role of light transmission. The use of communication fiber even ordinary multi-mode fiber can meet the requirements, and sensitive components can be a very flexible selection of high-quality materials. So the sensitivity of these sensors needs more optical coupling devices, the structure is more complex. The structure of sensing type fiber optic sensor is relatively simple with fewer coupling devices, but higher requirements on the optical fiber. It often needs to be sensitive to signal measurement, with good transmission characteristics. So far, most people adopt the former, but with the improvement of optical fiber manufacturing technology, sensor-type fiber optic sensors will also be widely used. According to the principle of light being modulated in optical fiber, fiber optic sensors can be divided into intensity modulation, phase modulation, polarization modulation, frequency modulation, wavelength modulation, and so on. Up to now, optical sensors have been able to measure more than 70 physical quantities. Fiber Optic Sensors have unique advantages over traditional sensors. (1) High sensitivity. Since light is a very short wavelength electromagnetic wave, its optical length is obtained by the phase of light. Taking an optical fiber interferometer as an example, due to the small diameter of the fiber used, its optical length is subject to slight mechanical external force or temperature change, causing a large phase change. Suppose that with a 10-meter optical fiber, a change of 1 ° C causes a phase change of 1000ard. If the minimum phase change that can be detected is 0.01ard, the minimum change in temperature that can be measured is 10 ° C, showing a high sensitivity. (2) Anti-electromagnetic interference, electrical insulation, corrosion resistance, intrinsically safe. Since fiber optic sensors transmit information using light waves, optical fibers are an electrically insulating, corrosion-resistant transmission medium and safe, which makes it easy and effective to use All kinds of large electromechanical, petrochemical, mine and other strong electromagnetic interference and flammable and explosive and other harsh environments. (3) Fast measurement. Light travels fastest and can transmit two-dimensional information, so it can be used for high-speed measurements. The analysis of radar and other signals requires an extremely high detection rate. The application of electronics is difficult to achieve. Using high-speed spectral analysis of light diffraction can be solved. (4) Large information capacity. The signal under test is a light wave carrier, and the light has a very high frequency. The contained frequency band is very wide. The same optical fiber can transmit multiple signals. (5) Suitable for harsh environments. Optical fiber is a dielectric, high voltage, corrosion-resistant, anti-electromagnetic interference that can be used for other sensors that do not adapt to the harsh environment. In addition, fiber-optic sensors are also characterized by their lightweight, small size, flexibility, wide measurement range, good reusability, and low cost. The application of fiber optic sensors is precise because fiber optic sensors have so many advantages, making it a very wide range of applications, involving petrochemicals, power, medicine, civil engineering, and many other fields. Video 1 Introduction of fiber optic sensorsII. Application of Light Sensor in Petrochemical Industry 2.1 The application of fiber optic sensor in the petrochemical systemIn the petrochemical system, due to the underground environment with high temperature, high pressure, chemical corrosion and electromagnetic interference, and other characteristics, the conventional sensor is difficult to play a role in the well. However, the fiber itself is no charge, small and light, easy to bend, anti-electromagnetic interference, and anti-radiation performance. Particularly it is suitable for flammable and explosive, strict restrictions and strong electromagnetic interference, and other harsh environments. Fiber optic sensors in the measurement of the good parameters play an irreplaceable role. It will become the oil and gas exploration and oil logging and other logging A field of broad market prospects of new technologies.  Fiber optic sensor application in oil and gas exploration. Because of its high-temperature capability, multi-communications, distributed sensing capabilities, and the fact that it requires only a small space to meet its use conditions, fiber optic sensors make it particularly unique in exploration drilling. The application of fiber optic sensors can be made into the downhole spectrometer, distributed temperature sensor, and optical fiber pressure sensor, and other products suitable for this special job requirement. (1) The downhole spectrometer fluid analyzer shown in Figure 1 can be used to understand the crude oil composition during the initial development process. It consists of two sensors: one is the absorption spectroscopy fiber and the other is the fluorescence and gas detector. Downhole fluid is introduced into the tubing by formation probes and the optical sensor is used to analyze the fluid within the tubing. Fluid analysis spectrometers provide in-situ downhole fluid analysis and improve formation fluid evaluation. (2) Distributed temperature sensors. Optical fiber distributed temperature sensors are the most popular fiber optic sensors for downhole applications. The application example is to monitor the steam injection heavy oil recovery system. Steam is injected into the heavy oil reservoir to reduce the viscosity of the oil, allowing heavy oil to be mined out. Downhole steam temperature can be as high as 250 ℃. Figure 1 Fluid analyzer structure(3) The fiber-optic pressure sensor is currently under development. Its main focus is on ultra-high temperature and downhole pressure monitoring tasks. Other commercial products based on fiber optic sensors are currently available. For example, fiber optic probes for multiphase flow measurements and distributed dynamic strain measurements. Its high reliability, high efficiency, and low power consumption are key factors in the success of optical fiber products in oil field applications. 2.2 The application of fiber optic sensor in oil loggingOil logging is one of the most basic and key aspects of the petroleum industry. The parameters such as pressure, temperature, and flow rate are important physical quantities in oil and gas wells. These advanced technologies are used for long-term Real-time monitoring, timely access to the information of oil and gas wells, the oil industry has a very important significance. Fiber optic sensors are insensitive to electromagnetic interference and withstand extreme conditions, including high temperatures and pressures, as well as strong shock and vibration, to measure borehole and well site environmental parameters with high accuracy, and have distributed measurement capabilities for fiber optic sensors. The spatial distribution gives the profile information. Moreover, the fiber optic sensor cross-sectional area is small, short in shape, in the wellbore occupies a very small space. Traditional electronic sensors do not have such features in the harsh underground environment. Fiber optic sensors can do downhole flow measurement, temperature measurement, pressure measurement, water (gas) measurement, density measurement, acoustic measurement. (1) Flow measurement. Because the intensity, phase, frequency, wavelength, and other characteristics of light in the optical fiber transmission process will be subject to flow modulation. A certain light detection method can convert the modulation into electrical signals, you can find the fluid flow, which is the fiber flow the working principle of the meter. (2) Temperature and pressure measurement. The distributed optical fiber measurement system (DTS) utilizes the Raman effect of the optical fiber to enable real-time monitoring of the temperature field where the fiber is located. The EFPI type (non-intrinsic FP interference) and FBG fiber optic sensors are wavelength-coded sensors. With high sensitivity, it also can simultaneously measure pressure, temperature, stress, and other parameters of the characteristics. The optical fiber thermal color temperature sensor is a reflective temperature sensor composed of a white light source and a multi-mode optical fiber.  The optical fiber radiation temperature sensor utilizes black body radiation energy. Its non-contact, measurable instantaneous temperature, fast response, and no need for heat balance time are available. In high-temperature measurement, the semiconductor absorption-type optical fiber temperature sensor utilizes the characteristic that the absorption edge wavelength of its semiconductor material shifts to a longer wavelength as the temperature increases, and an appropriate semiconductor light-emitting diode is selected so that its spectral range falls exactly on the absorption edge region. , So the light intensity through the semiconductor decreases with increasing temperature. (3)Water (Gas) Rate and transmission power of U-shaped fiber used for density measurement vary with the refractive index of the external medium. The lightwave serves as an information carrier and has nothing to do with the resistivity, flow pattern, and water quality of the mixed fluid. The fiber holding rate is based on this principle. The density sensor essentially solves the problem of the application of high water content without resolution and radioactive substances in the existing holding ratios. For the multi-phase fluids, the refractive indices of oil, water, and gas are all different, so the refractive index of the mixed fluid will follow. Change the ratio of oil, water, gas changes. Therefore, this refractive index modulation type fiber optic sensor can not only measure the fluid holding rate, fluid density can be measured at the same time, for its accuracy is higher. (4) Sonic measurement. Seismic waves propagate in different media and the waveforms of the received seismic waves will be different. According to different seismic waveforms, the sedimentary sequence and sedimentary structure can be identified to locate the reservoir, determine the gutter, detect the damage and fracture of the casing, and perforation, detect layers and determine the fluid flow, and so on. VSP seismic logging means that the geophone is placed in a well and the seismic signal is received by the geophone in the well by means of a micro-vibration generated by ground-derived seismic waves or fluid flow in the well.  The permanent downhole optical fiber three-component seismic survey has high sensitivity and directionality can produce high-precision spatial images. It can not only provide near-borehole images but also can provide strata images around the wellbore. And the measurement range can reach thousands of kilometers. It withstands harsh environmental conditions and has no moving parts and downhole electronics that can withstand strong shocks and vibrations and Can be installed in an extremely small space for complex completion string.  III. Application of Fiber Optic Sensors in Power Systems Because of the complicated structure and wide distribution of power system networks, various hidden dangers exist on the high-voltage power line and power communication network. Therefore, it is very important for distributed monitoring of various lines and networks in the system.  3.1 Applications in the high voltage cable temperature and strain measurementAt present, foreign countries (mainly Britain, Japan, etc.) have developed the distributed optical fiber temperature sensor products by utilizing the laser Raman spectroscopy effect. And domestically, we are actively carrying out research work in this area. The domestic begin to introduce the distributed optical fiber temperature sensing technology into the power system cable temperature measurement. In connection with the snow disasters suffered in southern China last year, we can consider that if we can lay sensor fiber optic cables in parallel on high-voltage cables and measure the temperature, pressure, and other parameters of power system cables and towers in real-time, we can make timely measurements, so as to minimize economic losses.  Fiber optic sensors in the power system will have a wide range of applications. Ideally, the fiber should be placed as close as possible to the cable core to more accurately measure the actual cable temperature. For direct-buried power cables, although the surface-mount fiber can not accurately reflect the change of cable load, it is more sensitive to the change of thermal resistivity of soil in the buried cable and can reduce the installation cost of optical fiber. 3.2 Application in electric power sensorsElectric power is the basic power reflecting the energy conversion and transmission in the power system. Electric power measurement is an important part of power metering. With the rapid development of the power industry, traditional electromagnetic measurement methods have increasingly exposed their inherent limitations, such as electrical insulation, electromagnetic interference, and magnetic saturation.  Therefore, people have been working hard to find new methods for measuring electrical power. It can be said that the advent of fiber optic sensors has brought people the gospel to solve this problem. The main characteristics of fiber-optic power sensors are: Since electric power sensing involves both voltage and current at the same time, it is usually necessary to consider both electro-optic and magneto-optic effects. At the same time, two kinds of sensing media or one multifunctional media are used as sensitive elements. The structure of the fiber electric power sensor head is relatively complicated; the optical sensor signal of the fiber electric power sensor sometimes includes voltage and current signals at the same time, so the signal detection and processing methods thereof will also be more complicated. 3.3  Application of optical fiber cable monitoringIn Power Systems The power system has a wide variety of optical cables. In addition, China has a vast area and the environment varies widely. Therefore, the environment of optical cables is also very complex. Temperature and stress are the main environmental factors that affect the performance of optical cables. Therefore, while monitoring the breakpoint of the optical fiber, the temperature and stress conditions of the optical cable are also monitored. It can be seen that the optical fiber cable has far-reaching fault warning and maintenance.  By measuring the frequency shift and intensity of the Brillouin scattered light along the length of the optical fiber, the temperature and strain information of the optical fiber can be obtained, and the sensing distance is relatively long, so it has far-reaching engineering research value. Based on Brillouin Optical Time Domain Reflectance (BOTDR) distributed optical fiber sensing system, using coherent detection technology, the system principle shown in Figure 2.  Figure 2 based on BOTDR sensing system principleThe BOTDR fiber sensing system measures the self-distribution of scattering signals of an optical fiber and its signal strength is very weak, but the coherent detection technology can be used to improve the signal-noise ratio of the system. This solution can be a single light source, single-ended work, the system is simple and easy to implement, and can simultaneously detect fiber breakpoints, loss, temperature, and strain.  IV. Fiber Optic Sensors in Medical Applications In medical fiber, sensors are mainly light-transmitting. With its small size, insulation, non-radio frequency, and microwave interference, high measurement accuracy and good affinity with living organisms, and other advantages. This article will mainly introduce the application of transmission optical fiber in pressure measurement, blood flow velocity measurement, and pH measurement. In addition, it can also be applied to the measurement of temperature and medical image transmission. 4.1 Pressure measurementCurrent clinically applied pressure sensors are mainly used to measure intravascular blood pressure, intracranial pressure, intracardiac pressure, bladder, and urethral pressure. The pressure sensor used to measure blood pressure is schematically shown in Figure3. The pressure-sensitive part is a water-repellent film on the sidewall of the tip of the probe catheter connected to the membrane by a cantilever micromirror and an optical fiber opposite the reflector for transmitting incident light to the reflector while The reflected light is also transmitted.  When there is pressure on the film, the film is deformed and can drive the cantilever to change the angle of the mirror. The light beam coming from the fiber is shone on the mirror and then reflected at the end of the fiber. Since the direction of the reflected light changes with the angle of the mirror, the intensity of the reflected light received by the optical fiber also varies. This change passes through the optical fiber to the other end of the photodetector into an electrical signal, so that by changing the voltage to know the size of the probe at the pressure.Figure 3 Optical fiber pressure gauge probe 4.2 Blood flow velocity measurement Doppler-type optical fiber speed sensor measurement of subcutaneous tissue flow velocity shown in Figure 4, this device uses the optical fiber end reflection phenomenon, the measurement system is simple in structure.Figure 4 optical fiber pressure gauge probeLaser light with a frequency of f passes through the lens and the fiber is sent to the epidermal tissue. For immobile tissue, such as the vessel wall, the reflected light does not produce a frequency shift; and for the red blood cells in the cortex capillary flow rate, the reflected light to produce a frequency shift, the frequency change △ f. The frequency shift of the reflected light The intensity is proportional to the concentration of erythrocytes and the change in frequency can be proportional to the velocity of erythrocytes. Emitted light collected by the optical fiber, the first on the light detector for mixing, and then into the signal processing instrument, which get the red blood cell velocity and concentration. 4.3 PH measurementA schematic diagram of the pH fiber optic sensor used to determine tissue and blood values is shown in Figure 4. Its working principle is the use of emission light, the intensity of transmitted light with the wavelength distribution of the spectrum to be measured. The sensor inserts two optical fibers into an ion-permeable cellulose capsule containing reagent, which penetrates the reagent when the needle is inserted into the tissue or blood vessel, causing the reagent to absorb light of a certain wavelength. Measured such changes, you can get the blood or tissue pH.Figure 5 Determination of pH fiber spectrometerV. Fiber Optic Sensor Features 1.High sensitivity. 2.The geometry has a wide range of adaptability, can be made into any shape of the fiber optic sensor. 3.You can create sensors sensing a variety of different physical information (sound, magnetic, temperature, rotation, etc.) of the device. 4.Can be used for high voltage, electrical noise, high temperature, corrosion, or other harsh environments. 5.But also with the inherent compatibility of optical telemetry technology. The advantages of fiber-optic sensors are that optical fiber sensors use light as a carrier for sensitive information, and use optical fibers as a medium for transmitting sensitive information. Compared with conventional sensors. They have the characteristics of optical fiber and optical measurement and have a series of unique advantages. Good electrical insulation, anti-electromagnetic interference, non-invasive, high sensitivity, easy to achieve long-distance monitoring of the signal under test, corrosion resistance, explosion-proof, flexible optical path, easy to connect with the computer. Sensors are developed in the direction of sensitivity, precision, adaptability, compactness, and intelligence. They can serve as human eyes and ears where people cannot reach(such as high-temperature areas, are as harmful to humans, or nuclear radiation areas). But it is also beyond the physical boundaries of human beings, outsiders can not feel the sensory information. FAQ 1. How does a fiber optic sensor work?Fiber optic sensors work based on the principle that light from a laser or any superluminescent source is transmitted via an optical fiber, experiences changes in its parameters either in the optical fiber or fiber Bragg gratings and reaches a detector which measures these changes. 2. What are fiber optic sensors used for?Optical fibers can be used as sensors to measure strain, temperature, pressure and other quantities by modifying a fiber so that the quantity to be measured modulates the intensity, phase, polarization, wavelength or transit time of light in the fiber. 3.How are fiber optic sensors classified?Based on the operating principle or modulation and demodulation process, a optical fiber sensor can be classified as intensity, a phase, a frequency, or a polarization sensor. All these parameters may be subject to change due to external perturbations. ... These sensors are widely used as chemical sensors. 4. What is active and passive optical fiber sensor?Active fibre optic. -In optical fiber communication, because the signal usually decades during long distance transformation, you need to add an amplifier to boost the signal. Passive fibre optic. - Simply receive light data from the environment, it is commonly used for illumination (Fiber optical lighting. 5. What are the characteristics of optical fiber sensors?Optical fiber sensors have unique advantages, such as high sensitivity, immunity to electromagnetic interference, small size, light weight, robustness, flexibility, and the ability to provide multiplexed or distributed sensing. 6. Which is a use of fiber optics?They are widely used in lighting, both in the interior and exterior of vehicles. Because of its ability to conserve space and provide superior lighting, fiber optics is used in more vehicles every day. Also, fiber optic cables can transmit signals between different parts of the vehicle at very fast speed. 7. Why optical fiber is used for communication?Optical fiber is used by telecommunications companies to transmit telephone signals, Internet communication and cable television signals. ... Due to lower attenuation and interference, optical fiber has advantages over copper wire in long-distance, high-bandwidth applications. 8. Is fiber optic WIFI?Like any Internet service, fiber optic Internet download speeds depend on your connection. Not all fiber services are created equal, much like broadband. ... You can download more, faster, with fiber. Fiber Internet is more reliable than copper and less 'patchy' than Wifi. 9. Is fiber optic analog or digital?Digital signals can be transmitted long distances without degradation as the signal is less sensitive to noise. Fiber optic datalinks can be either analog or digital in nature, although most are digital. Both have some common critical parameters and some major differences. 10. How much data can a fiber optic cable transmit?A new fiber-optic system can carry 800 gigabits of data per second, a big step up from top speeds of 100 or 200 gigabits in today's data centers. You May Also Like:GPS and inertial sensors for driverless applicationsA New Technology for Advancing Opticals,Sensors Even Resistant SupercapacitorsSensors are Always In a State of Rapid Progress

SummaryResearchers at TU Wien have succeeded in developing a method for the controlled manufacture of porous silicon carbide. Silicon carbide has significant advantages over silicon; it has greater chemical resistance and can therefore be used for biological applications, for example, without any additional coating required.Extremely fine porous structures with tiny holes – resembling a kind of sponge at nano level – can be generated in semiconductors. This opens up new possibilities for the realization of tiny sensors or unusual optical and electronic components. There have already been experiments in this area with porous structures made from silicon.To demonstrate the potential of this new technology, a special mirror that selectively reflects different colors of light has been integrated into a SiC wafer by creating thin layers with a thickness of approximately 70nm each and with different degrees of porosity. “There is a whole range of exciting technical possibilities available to us when making a porous structure with countless nano holes from a solid piece of a semiconductor material,” says Markus Leitgeb from the Institute of Sensor and Actuator Systems at TU Wien. Leitgeb developed the new material processing technology as part of his dissertation with Professor Ulrich Schmid in cooperation with CTR Carinthian Tech Research AG and sponsored by the Competence Centers for Excellent Technologies (COMET) program.“The porous structure influences the manner in which light waves are affected by the material. If we can control the porosity, this means we also have control over the optical refractive index of the material.” This can be very useful in sensor technology – for example, the refractive index of tiny quantities of liquid can be measured using a porous semiconductor sensor, thus allowing a reliable distinction between different liquids. Another attractive option from a technical and application-oriented perspective is to first make certain areas of the SiC wafer porous in a highly localized manner, before depositing a new SiC layer over these porous areas, and then causing the latter to collapse in a controlled manner – this technique produces microstructures and nanostructures which can also play a key role in sensor technology.  However, in all these techniques it is crucial that the appropriate starting material is selected. “Until now, silicon has been used for this purpose, a material with which we already have a lot of experience”, says Professor Schmid. Silicon also has significant drawbacks, however; under harsh environmental conditions, for example in extreme heat or in alkaline solutions, structures made of silicon are attacked and rapidly destroyed. Therefore, sensors made of silicon are often not suitable for biological or electrochemical applications. For this reason, at TU Wien, attempts have been made to achieve something similar with the semiconductor silicon carbide, which is biocompatible and considerably more robust from a chemical perspective. Some special tricks were required, however, in order to produce porous structures from silicon carbide. THE COLOR-SELECTIVE MIRRORFirst, the surface is cleaned, and then partially covered with a thin layer of platinum. The silicon carbide is then immersed in an etching solution and exposed to UV light, in order to initiate the oxidation processes. This causes a thin porous layer – initially 1μm thick – to form in these areas that are not coated with platinum. An electrical charge is then also applied in order to be able to precisely set the porosity and the thickness of the subsequent layers. Here, the first porous layer promotes the formation of the first pores when the electrical charge is applied.“The porous structure spreads from the surface further and further into the interior of the material”, explains Markus Leitgeb. “By adjusting the electrical charge during this process, we can control what porosity we want to have at a given depth.” In this way, it was possible to produce a complex layered structure of silicon carbide layers with higher and lower levels of porosity, which is finally separated from the bulk material by applying a high voltage pulse. The thickness of the individual layers can be selected such that the layered structure reflects certain light wavelengths particularly well or allows certain light wavelengths to pass through, resulting in an integrated, color-selective mirror. “We have thus demonstrated that our new method can be used to reliably control the porosity of silicon carbide on a microscopic scale”, says Ulrich Schmid. “This technology promises many potential applications, from anti-reflective coatings, optical or electronic components and special biosensors, through to resistant supercapacitors.” 

CCD image sensors still remain preferable in some specialised application.Today I would like to talk something about CMOS image sensor technology. As the development of image sensor,CMOS technology is widely used in most machine vision applications.What's excited,perhaps as the concepts behind industry 4.0 become adopted more broadly--the need for mre capable vision systems has grown sharply. This is a video of CCD vs CMOS sensors Catalog   Historical and modern CMOS Improve productivity, support high bandwidth   readout Inherent flexible available About the high resolution Design the right products Conclusion FAQ Machine vision systems use images to gather information on a system or process and to then make decisions based on the image captured.While such systems are dependent upon lighting and software,the camera-and the image sensor within it-is the key component in the overall operation of the system,as well as the ability to improve manufacturing quality and increase productivity.At a high-level,a typical machine vision application involves som combinaton of basic measurement,counting or inspection functions.Objects may be assessed to confirm the number of objects present,to determine the number and size of features or their quality level.So machine vision could be used to not only determine that the proper number of holes have been drilled into an item, but also to verify the spacing and shape of each hole. Similarly, the location of an object may be determined in order for it to be picked up by a robot arm or to determine whether a feature is in the correct place. Other functions include reading a barcode, performing character recognition or measuring the level of a fluid.So machine vision could be used to not only determine that the proper number of holes have been drilled into an item, but also to verify the spacing and shape of each hole. Similarly, the location of an object may be determined in order for it to be picked up by a robot arm or to determine whether a feature is in the correct place. Other functions include reading a barcode, performing character recognition or measuring the level of a fluid.   Historical and modern CMOS Historically, machine vision systems have required CCD image sensors because of their high image quality and performance.  Today, however, CMOS image sensors have jumped to the forefront for many machine vision applications. Advances in CMOS pixel design have made the imaging quality available from this platform sufficient for a variety of different end uses.Modern CMOS image sensor platforms, such as that used in ON Semiconductor’s PYTHON family, are based on a global shutter pixel design that enables the capture of moving objects without the introduction of motion artefacts. In-pixel correlated double sampling provides low readout noise, while on-chip fixed pattern noise correction helps preserve image quality. Combined with a 10bit A/D converter and a dynamic range of 60dB, these features allow machine vision systems to leverage the intrinsic advantages of a CMOS platform in their operation.   Improve productivity, support high bandwidth readout With many machine vision applications looking to operate at ever higher speeds in order to increase productivity, image sensors must support high bandwidth readout. The output architecture of the CMOS platform enables this as additional digital outputs can be added to increase the available bandwidth. For example, the use of up to 32 separate LVDS outputs enables high resolution PYTHON devices to realise bandwidths that exceed those of modern computer interfaces, including 10Gbit Ethernet or USB 3.1. The ability to output at up to 80frame/s from a 25Mpixel device is well beyond the capabilities of standard CCD designs. Inherent flexible available The inherent flexibility available in CMOS output designs allows the frame rate to be further increased when operating in Region of Interest (ROI) mode, where only a portion of the image sensor array is read out. With proper design considerations, the speed increase when operating in this manner can scale by both the x and y dimensions of the ROI, enabling faster frame rates than can be realised when using a more standard CMOS output design, which only scales the x dimension. Consider the frame rates from the PYTHON 5000 image sensor compared to theoretical frame rates from a similar 5Mpixel sensor using a standard CMOS output. At full resolution, both designs would provide approximately 100frame/s, but when reading out a 1280 x 720 pixel ROI, the the PYTHON device’s frame rate increases to almost 600frame/s, while the standard output design would increase to only 300frame/s. This can be an important differentiator.    About the high resolution While high resolution can provide finer detail, this must be balanced by making sure that too much information is not captured, which would slow data processing. In addition to having the right number of pixels, they need to be in the appropriate aspect ratio for the application. For example, an aspect ratios of 1:1 is often used in pick and place applications to maximise image capture across the full field of view. Different spectral sensitivities, such as colour, monochrome and extended near infrared (NIR), may also be required to optimise the imaging system for the application. In order to do this, a camera manufacturer will look for an integrated family of image sensor products that includes multiple resolution nodes and colour options to support a portfolio of products.The PYTHON family has more than 40 options, with resolutions ranging from VGA to more than 25Mpixel. These devices are available in multiple configurations, including monochrome, Bayer Color and extended NIR sensitivities. Selected devices are available in low-power configurations or with removable tape to protect the image sensor during the camera assembly process.   Design the right products Avent Silica offers a range of evaluation kits to help designers understand the performance available from the PYTHON family of image sensors.These kits include an image sensor,the appropriate sensor headboard,FPGA evaluation board and software and accessories.The Flexible design also allows the evaluation hardware to be use with other PYTHON devices by purchasing additional image sensors.After identifying the most appropriate image sensor, designers then need to consider the remainder of the camera design. Complementary products from ON Semiconductor include embedded boards, power and signal chain components that allow engineers to choose between modular solutions and the flexibility of a discrete design. If a machine vision system needs to be brought to market quickly, it may not be possible to build it from the ground up. For those applications, Avnet Silica products such as the PYTHON-1300-C camera module. Based on the PYTHON 1300 colour image sensor and featuring a 0.5in SXGA CMOS image sensor with a resolution of 1280 x 1024 pixels, the module can be combined with Avnet Silica’s MicroZed Embedded Vision Carrier Card and the Smart Vision Development Kit to provide a complete hardware design, leaving the designer to only write the application software. Conclusion Because of the combination of image quality,bandwidth,image flexiblity and configuration flexiblity available from MOS image sensors has accelerated adoption of this technology in machine vision applications.What's celebrating,The imaging capabilities of such devices has ushered in a new level of performance and functionality for industrial imaging and CMOS sensor based imaging is now suitable for use in almost every type of design.   FAQ   1. How does a CMOS image sensor work? Unlike CCD sensors that use high-voltage analog circuits, CMOS sensors employ a smaller digital circuitry that uses less power, and are in principle free from smear (vertical white streak in the image taken under bright light) and blooming (corruption of images such as white spots).   2. Which sensor is better CCD or CMOS? CMOS sensors have thousands. This means that CMOS cameras can read out incredibly fast, even 100X faster than a comparable CCD. For long-exposure applications that is not so important, but it is especially important for video cameras.   3. Is CMOS a full frame sensor? "Full frame" is a description of sensor size, sort of... "CMOS" is a name for semiconductor technology used to make sensors. So, they are definitely different, and not comparable.   4.What is CMOS sensor type? A CMOS sensor is an electronic chip that converts photons to electrons for digital processing. CMOS (complementary metal oxide semiconductor) sensors are used to create images in digital cameras, digital video cameras and digital CCTV cameras.   5. What is the function of image sensor? An image sensor is a device that allows the camera to convert photons – that is, light – into electrical signals that can be interpreted by the device. The first digital cameras used charge-coupled devices, facilitating movement of the electrical charge through the device so it could be modulated.   6. What is difference between CCD and CMOS? The biggest difference is that CCD sensors create high quality images with low noise (grain). CMOS images tend to be higher in noise. CCD sensors are more sensitive to light. CMOS sensors need more light to create a low noise image at proper exposure.   7. What CCD means? Charged Coupled Device. Stands for "Charged Coupled Device." CCDs are sensors used in digital cameras and video cameras to record still and moving images. The CCD captures light and converts it to digital data that is recorded by the camera. For this reason, a CCD is often considered the digital version of film.     8. What is CCD and CMOS? CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors are two different technologies for capturing images digitally. Each has unique strengths and weaknesses giving advantages in different applications.   9. Is CMOS sensor good? CMOS sensors traditionally have lower quality, lower resolution and lower sensitivity. CMOS sensors are just now improving to the point where they reach near parity with CCD devices in some applications. CMOS cameras are usually less expensive and have great battery life.   10. How does a CCD work? Fundamentally, a charge coupled device (CCD) is an integrated circuit etched onto a silicon surface forming light sensitive elements called pixels. Photons incident on this surface generate charge that can be read by electronics and turned into a digital copy of the light patterns falling on the device.