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Introduction Biomedical sensors are conversion devices that convert physiological information of the human body into electrical information that has a definite functional relationship with it. The information it picks up is the physiological information of the human body, and its output is often expressed in electrical signals by sensors. Figure 1. Health Care with Sensors Catalog Introduction Ⅰ Working Principle Ⅱ Biomedical Sensor Characteristics Ⅲ Classifications Ⅳ Biomedical Sensors Functions Ⅴ Biomedical Sensors Applications 5.1 Patient Lift Chair 5.2 Sports Rehabilitation Machine 5.3 Artificial Prosthesis 5.4 Infusion Pump 5.5 Baby Incubator 5.6 Infrared Thermometer Ⅵ Biomedical Sensors Development Ⅶ FAQ Ⅰ Working Principle In modern medicine, biomedical sensors actually replace the doctor’s sensory organs and play an extended role. It has become a key technology that restricts the development of high-level advanced medical equipment. The important technological foundation of the information society. There are two types of human physiological information: electrical information and non-electrical information. In terms of distribution, there are internal (such as blood pressure and other types of pressure), body surface (such as various types of bioelectricity such as ECG) and the external (such as infrared, biomagnetism, etc.).   Ⅱ Biomedical Sensor Characteristics As an important branch of sensors, the design and application of biomedical sensors must consider the influence of human factors, such as the particularity and complexity of biological signals, and the biocompatibility, reliability and safety of biobiomedical sensors.1) The sensor itself has good technical performance, such as sensitivity, linearity, hysteresis, repeatability, frequency response range, signal-to-noise ratio, temperature drift, zero drift, sensitivity drift, etc.2) The shape and structure of the sensor should be adapted to the anatomical structure of the tested part, and the damage to the tested tissue should be small.3) The sensor has a small impact on the measured object. In other words, it will not bring a burden to physiological activities, and does not interfere with normal physiological functions of humans.4) The sensor must have enough firmness so that it will not fall off or be damaged when use it.5) The sensor and the human body must have sufficient electrical insulation to ensure the safety.6) When the sensor enters the human body, it can adapt to the chemical action in the biological body. For example, it is compatible with the chemical composition in the biological body, is not easy to be corroded, has no adverse irritation to the human body, and is non-toxic.7) If the sensor enters the blood or is buried in the body for a long time, it should not cause blood problem.8) The sensor should be simple to operate, easy to maintain, and easy to sterilize in structure. Figure 2. Health Monitoring with Biobiomedical Sensor Ⅲ Classifications 1. According to the working principle:🔺Chemical sensorUse the principle of chemical reaction to convert chemical composition and concentration into electrical signals.🔺Biological sensorUse the selective identification of biologically active substances to determine biochemical substances.🔺Physical sensorTake advantage of physical changes in materials.🔺Bioelectric electrode sensorUse the body's various bioelectricity (cardioelectricity, brain electricity, myoelectricity, neuron discharge, etc.).2. According to the type of detection:Displacement sensor, flow sensor, temperature sensor, speed sensor, pressure sensor, etc. For pressure sensors, including metal strain gauge pressure sensors, semiconductor pressure sensors, capacitive pressure sensors, etc. For temperature sensors, including thermistors, thermocouples, PN junction temperature sensors and other sensors that can detect temperature.3. According to human senses:1) Vision SensorIncluding various optical sensors and other sensors that can replace vision functions.2) Hearing SensorIncluding various pickups, piezoelectric sensors, capacitive sensors and other sensors that can replace auditory functions.3) Olfactory SensorInclude various gas-sensitive sensors, and sensors that can replace the olfactory function.This classification method is conducive to the development of bionic sensors. In addition to the widely used sensor classification methods, there are also multiple classification standards based on sensor materials, structures, energy conversion fractions, etc., all with their own advantages and limitations.   Ⅳ Biomedical Sensors Functions (1) Provide diagnostic information, such as heart sounds, blood pressure, pulse, blood flow, respiration, body temperature and other information for clinical diagnosis and medical research.(2) Monitoring: Long-term continuous measurement of certain parameters, monitoring whether these parameters are within the specified range, in order to check the patient's recovery process, and take actions when abnormalities occur. For example, after a heart operation, it is necessary to monitor changes in a series of parameters such as body temperature, pulse, arterial pressure, venous pressure, respiration, and electrocardiogram of a patient.(3) Human body control: Use the detected parameters to control the physiological process of the human body. For example, an automatic respirator uses a sensor to detect the patient’s breathing signal to control the movement of the respirator to synchronize the breathing of the human. Another example is the electronic prosthesis, which uses the measured electromyographic signal to control the movement of the human prosthesis. What’s more, have the blood flow and blood pressure control of cardiopulmonary bypass.(4) Clinical tests: In addition to collecting information directly from the human body, diagnostic information is often obtained from various body fluids (blood, urine, saliva, etc.) samples. This type of information is called biochemical test information. It is obtained by using chemical sensors and biosensors, and is an indispensable basis for diagnosing various diseases. Figure 3. Tiny Biobiomedical Sensor Ⅴ Biomedical Sensors Applications 5.1 Patient Lift Chair Electric chair lifts can provide a safe and efficient way to transfer patients from one place to another, helping to ensure the safety of patients. These basic equipment can greatly reduce the burden on nursing staff when using other transfer methods to keep on patient safety and comfort. These chairs have a lightweight and portable design and are suitable for many medical care environments. For example, modern versions of these chairs also incorporate load cells to further enhance their performance. The weighing sensor designed to measure the weight of the patient can be connected to an alarm, and when the load exceeds the safety upper limit, an alarm will be issued to the health staff immediately. 5.2 Sports Rehabilitation Machine Usually used in physiotherapy, these machines are usually used to exercise the patient's muscles as part of the therapy to restore the patient's motor skills and mobility after the patient has suffered a stroke or sports injury. With our advanced technology, modern rehabilitation machines can now provide intelligent sensing capabilities to detect the movement of patients. By integrating load cells, we are now able to provide the controller with the real-time feedback needed to predict the patient's next movement. The intelligent resistance control can increase or decrease the resistance of the exercise machine according to the force measured from the patient's actions, thereby promoting the patient's muscle growth in the most suitable way. The load cell can also be used to measure the weight of the patient, so that the rehabilitation machine can estimate the height of the patient, and pre-position the handle of the machine at the correct level in an efficient manner. 5.3 Artificial Prosthesis After a long period of development, artificial prostheses have been improved in many aspects, from the comfort of materials to the integration of electromyographic control using electrical signals generated by the wearer’s own muscles, to the fact that artificial prostheses are extremely realistic in appearance and have the same skin texture. Even match pigments and details such as hair level, nails and texture.With the integration of advanced sensors into artificial prostheses, further improvements can be brought about. They are aimed at enhancing the natural movement of artificial prostheses for arms and legs, and providing the correct amount of strength assistance during exercise. Our solutions include weighing sensors and custom force sensors that can be built into artificial prostheses. These sensors can measure the pressure of each patient's movement, thereby automatically changing the resistance of the artificial prosthesis. This feature allows patients to adapt and perform daily tasks in a more natural way. 5.4 Infusion Pump It is the most commonly used and basic tool in the medical environment and can achieve flow rates from 0.01 mL/hr to 999 mL/hr. Our customized solutions help reduce errors and achieve the goal of providing high-quality and safe patient care. And the solution can provide reliable feedback to the infusion pump to ensure continuous and accurate drug delivery, and the liquid is delivered to the patient in a timely and accurate manner, reducing the supervision workload of medical staff. 5.5 Baby Incubator Rest and reducing bacterial exposure are key factors for newborn care. Therefore, the baby incubator is designed to protect weak babies by providing a safe and stable environment. The load cell is incorporated into the incubator to achieve accurate real-time weight measurement without affecting the baby's rest or exposing the baby to the external environment. 5.6 Infrared Thermometer It is a kind of devices with non-contact temperature sensor, its sensitive element and the measured object are not in contact with each other, also known as non-contact temperature measuring instrument. This kind of instrument can be used to measure the surface temperature of moving objects, small targets and objects with small heat capacity or rapid temperature changes (transient), and it can also be used to measure the temperature distribution of the certain field. In today's outbreak of COVID-19, physical contact has been minimized and the spread of bacteria and viruses has been reduced greatly.   Ⅵ Biomedical Sensors Development Among them, the research and development of the sensor itself has two branches. One is related to the basic research of the sensor, that is, the research on the new technology and new principles required by the sensor.In recent years, the development of medical sensor products has become more and more popular, and the productization of sensor technology in the field of medical equipment products has become increasingly popular. Innovative medical products such as wearables, artificial intelligence AI, surgical robots, etc. are emerging in an endless stream. Modern medical sensor technology has got rid of the technical shortcomings of traditional biomedical sensors such as large size and poor performance, and has formed new development directions such as intelligence, miniaturization, multi-parameter, remote control, and non-invasive detection.The development of biomedical sensors is already one of the key technologies restricting the development of high-end and advanced medical equipment, and it is also one of the main driving forces to promote the development of medicine.   Ⅶ FAQ 1. Why are sensors used in healthcare?Sensors are used in electronics-based medical equipment to convert various forms of stimulation electrical signals for analysis. Sensors can increase the intelligence of medical equipment, such as life-supporting implants, and can enable bedside and remote monitoring of vital signs and other health factors. 2. What sensors are used in patient monitoring system?Thus, different types of sensors can be used (e.g., GPS receiver, accelerometer, ECG, blood pressure, blood glucose, body temperature, and breathing sensor). 3. What are the sensors used in biomedical applications?Biomedical sensor classification. Many different kinds of sensors can be used in biomedical application.Oxygen and carbon dioxide sensor for blood.Heart sound sensor.Blood flow sensor.Respiration sensor.Blood pressure sensor.Electrochemical electrode. 4. What is the main difference between biosensors and biomedical sensors?Biosensors, which can be considered a special subclassification of biomedical sensors, are a group of sensors that have two distinct components: a biological recognition element, such as a purified enzyme, antibody, or receptor, that functions as a mediator and provides the selectivity. 5. Can biomedical sensors be placed anywhere inside the body?Biosensors can be placed inside your body as well. Dr. Natalie Wisniewski, a biomedical engineer at a medical device company in San Francisco called Profusa, is developing miniature sensors that can be injected under the skin. These sensors automatically track chemicals in your body without drawing blood. 6. What are the types of biomedical sensor?While talking about biomedical engineering, we come across biomedical sensor terminology, which is then divided into three types: physical sensors, chemical sensors, and biosensors. Physical sensors are used to evaluate blood pressure, biologic magnetic field, etc. 7. Which sensors are used in biomedical applications?There are different types of physical sensors used for biomedical applications: Radiation sensors address the X-ray and gamma ray-based sensors, Mechanical sensors include ultrasound and pressure sensor Thermal sensors include a range of sensors such as thermocouple, thermistor, thermopile, optical fiber devices, P-N. 8. What are biomedical sensors used for?In medicine and biotechnology, biomedical sensors are used to detect specific biological, chemical, or physical processes, which then transmit or report the monitored data. These sensors can also be components in systems that process clinical samples, such as increasingly common lab-on-a-chip devices. 9. What sensors are used in hospitals?Types of medical sensorsThe primary sensors used within medical devices are pressure, force, airflow, oxygen, pulse oximetry, temperature, and barcode sensing. The above sensors play a critical role in the operation of the equipment. 10. What sensors are used in patient monitoring system?Thus, different types of sensors can be used (e.g., GPS receiver, accelerometer, ECG, blood pressure, blood glucose, body temperature, and breathing sensor). 11. What are the temperature sensors?A temperature sensor is a device used to measure temperature. This can be air temperature, liquid temperature or the temperature of solid matter. There are different types of temperature sensors available and they each use different technologies and principles to take the temperature measurement.

Ⅰ IntroductionA motion sensor is a kind of security system. And the linchpin of your security system is a motion sensor (or motion detector) as it detects when someone is in your home who should not be there. A motion sensor detects movement in an area with one or more technologies.When a sensor detects motion, it sends a signal to the control panel of your security system, which is connected to your monitoring center. This notifies you and the monitoring center that there is a potential threat in your home.CatalogⅠ IntroductionⅡ Motion Sensor Related Video:Ⅲ What is a Motion Sensor?Ⅳ Types of Motion SensorsⅤ How do Active Ultrasonic Sensors and Passive Infrared (PIR) Work?5.1 Active Ultrasonic Sensors5.2 PIR SensorsⅥ How to Install a Motion Sensor?Ⅶ Other Uses for Motion SensorsⅧ FAQ Ⅱ Motion Sensor Related Video:How PIR Sensor Works and How To Use It with ArduinoMotion Sensor Video Description：In this Arduino Tutorial we will learn how a PIR Sensor works and how to use it with the Arduino Board for detecting motion. Ⅲ What is a Motion Sensor?A motion sensor (or motion detector) is a genre of electronic device that detects and calculates movement. We can often find motion sensors in the home and business security systems,  as well as in phones, paper towel dispensers, game consoles, and virtual reality systems. Unlike many other types of sensors, motion sensors can not be handled and isolated as they are in embedded systems comprised of three major components: a sensor unit, an embedded computer, and hardware (or the mechanical component). Because motion sensors can be customized to perform highly specific functions, these three parts vary in size and configuration. Motion sensors, for example, can be used to activate floodlights, sound audible alarms, activate switches, and even alert the police. Figure1: Motion SensorⅣ Types of Motion SensorsActive Ultrasonic SensorsActive sensors have a transmitter as well as a receiver. This sensor detects motion by measuring changes in the amount of sound or radiation that is reflected back into the receiver. Passive infrared (PIR)A passive infrared sensor detects body heat (infrared energy) by monitoring temperature changes. This is the most common type of motion sensor found in home security systems. Figure2:Passive infrared (PIR) Microwave (MW)This type of sensor emits microwave pulses and detects reflections from moving objects. 1 They have a larger coverage area than infrared sensors, but they are more expensive and susceptible to electrical interference. Figure3:Microwave (MW) Dual technology motion sensorsThis type of sensor emits microwave pulses and detects reflections from moving objects. 1 They have a larger coverage area than infrared sensors, but they are more expensive and susceptible to electrical interference. Figure4: Dual technology motion sensorsEach sensor type operates in a different part of the electromagnetic spectrum (ranging from passive to active). Dual technology motion sensors are less likely to cause false alarms than other types because both sensors must trip to sound an alarm. This is not to say that they never cause false alarms. Less common types of motion detectorsTomographic motion sensors are composed of several nodes. The nodes connect to form a mesh network. When the link between two nodes is broken, these sensors detect the presence of a person or object.Vibration motion sensors detect people and objects by detecting small vibrations caused by movements such as footsteps. Ⅴ How do Active Ultrasonic Sensors and Passive Infrared (PIR) Work?The two most common motion sensor technologies are active ultrasonic sensors and passive infrared sensors, both of which are well-known for their accuracy and dependability.5.1 Active Ultrasonic SensorsActive ultrasonic sensors produce ultrasonic sound waves that are higher in frequency than the human hearing range. These waves are bouncing off nearby objects and returning to the motion sensor. A transducer within the sensor serves as a signal waypoint, sending the pulse and receiving the echo. The sensor calculates the distance between itself and the target by measuring the time between signal transmission and reception. Most motion sensors allow you to adjust the sensitivity, which means it won't trigger if the distance between the sensor and the object is too great. If the received signal falls within the specified parameters, the motion sensor will activate, alerting you that someone or something is close to the sensor.Motion sensors installed at entry points such as windows and doors can be programmed to sound a burglar alarm. Door and window sensors are specifically designed to detect an intruder, so you should not experience false alarms or excessive notifications.Ultrasonic sensors are capable of detecting objects regardless of color, surface type, or material type (i.e., metallic vs. non-metallic). They can detect translucent objects as well, though this is typically reserved for industrial applications.Figure5:Active ultrasonic sensors 5.2 PIR SensorsPIR sensors are more complicated than active ultrasonic sensors, but the results are the same.Walls, floors, stairwells, windows, cars, dogs, trees, people—you name it—emit heat. Temperature can be detected using infrared waves. Infrared motion sensors detect the presence of a person or object by measuring the temperature change in a specific area. 5.3 Example of PIR SensorsTo demonstrate how this works, we'll use a motion detection camera, though any PIR motion sensor will do.A PIR camera contains two sensors. When no one is present, the PIR camera detects ambient IR emitted by background objects such as walls and doors. When a person (or animal, object, etc.) moves in front of the camera, the first sensor detects their heat signature, causing the camera to activate, triggering your alarm, and sending you an alert. If the object moves out of the camera's field of view, the second sensor will activate, noting the sudden drop in temperature.These temperature changes are used by a PIR motion sensor to detect the presence of a person or object. PIR sensors, like active ultrasonic sensors, can be configured to ignore small changes in IR, allowing you to walk around your home or business without setting off alarms all day and night. Ⅵ How to Install a Motion Sensor?Typical motion sensors have a range of up to 80 feet, which means that a single sensor will most likely not cover a long hallway or an open workspace. You can have your security system installed by a security company such as Bay Alarm. Our installers will examine the layout of your space to determine the best location for motion sensors. Our goal, as with security cameras, fire alarms, and burglar alarm installations, is to make your home or business as secure as possible, with devices and components strategically placed.After the sensors have been installed, a security agent will integrate them with your burglar alarm system. Using one of two apps: SureHome by Bay Alarm or Bay Alarm Access, you'll have quick access to your entire security system from your phone.If you decide to do your own security, make sure to follow the instructions that come with the sensor. Here are some pointers for installing motion detectors in your home or business: Step1:Take your motion detector out of the box.Your motion sensor kit should include instructions as well as mounting hardware. If your device has separate batteries, insert them into your motion sensor now. Step2:TDecide on a locationCorners are ideal because they allow you to position infrared sensors to cover the most ground. Most motion sensor designs have angled edges with screw holes to fit neatly into a room's corner.Mount your motion detector high on the wall to get the best coverage—but avoid putting it over a large piece of furniture, like a bookshelf or entertainment center, because it will limit the passive infrared energy range.Mount your motion sensor opposite the main entrance—this applies in every room or hallway where you place these sensors so they can detect intruders right away. Step3:Mount the sensorBecause passive infrared sensors are lightweight, you won't need drywall anchors or studs. A standard screwdriver will suffice, but an electric screwdriver or drill will expedite the process.Most motion detectors include a mounting bracket that detaches from the main body of the device, allowing you to screw it into the wall first, then clip the motion sensor back in. This also makes removing the motion detector from the wall during maintenance easier. Other infrared sensors may necessitate a complete disassembly before mounting. Step3: Connect your sensor to your systemConnect your motion sensor to your system according to the manufacturer's instructions. Most DIY systems will walk you through this process, frequently using the main keypad or a mobile app to configure and adjust your motion detectors.TIPS: Z-Wave-enabled smart motion sensors connect to your phone for easy access and notifications. Whether you're just getting started with your smart home build or you already have dozens of connected devices, Z-Wave-enabled motion sensors are a worthwhile addition. Step4: Adjust your motion detection settingsWhen you arm your system, most motion detectors have three main settings:In instant mode, any movement sets off an alarm.In entry delay mode, the sensor operates on a delay; even if it detects motion, you have approximately 30–60 seconds to disarm the system before an alarm is triggered.Interior follow-up mode operates on an entry delay, but only when the door contact triggers first—it sounds an instant alarm if it detects motion in the home without the door contact triggering. Step6: Maintain your motion detectorDust and debris can accumulate on the screen of your motion sensor over time, interfering with the infrared energy and making it less effective at motion detection. Use a dry or slightly damp microfiber cloth to clean it at least once every couple of months.If you decide to paint a wall near your motion sensor, make sure to first remove the device. If paint gets on a passive infrared motion sensor, it must be replaced. Additional tips for installing motion sensorsTake into account the size of your pets.Overhangs reduce range.Do not obstruct the infrared.Not all motion sensing light switches are created equal. Ⅶ Other Uses for Motion SensorsMotion sensors are useful for more than just home security. Many industrial fields use them on assembly lines to count the number of products and to shut down dangerous equipment if someone gets too close.Here are a few other uses for motion sensorsTo automate the opening and closing of doorsTo activate and deactivate automatic water faucets and toiletsWhen a person enters a room, lights are turned on.ATM display controlAt ticket vending machinesFor certain parking meter Ⅷ FAQ1. Which motion sensor is best?Best Motion SensorsPhilips. Hue Smart Motion Sensor. A solid choice if you are looking for a motion sensor for indoor use that's also intuitive. ...First Alert. Motion Sensing Light Socket. ...SadoTech. Wireless PIR. ...Chamberlain. Wireless Motion Sensor. ...1byone. Safety Driveway Patrol.2. Are motion sensors effective?Motion sensors are proven to be effective at leading to apprehensions. ... Motion sensors can be more cost-effective for rooms with many windows that would require several sensors to protect. A motion detector can alert you immediately if there is movement is detected.3. What can set off a motion detector?What can set off a motion detector? Moveable objects such as balloons, curtains, decorations, and pets can set off motion detectors. How to prevent this: Consider positioning motion sensors above waist level so pets can move around freely, and away from curtains and other items that may move or drift.4. Do motion detectors work in the dark?The short answer is yes. Motion sensors do work in complete darkness, as none of the motion sensors mentioned above are reliant on using images to detect motion. Instead of images, PIR motion sensors detect changes in the level of received infrared. Likewise, ultrasonic motion sensors also do not require images.5. How long do motion sensors last?On average, a motion detector light will stay on for up to 20 minutes. That amount of time is extended each time a sensor detects fresh movement, so it is possible for a motion detector light to stay on for much longer than 20 minutes at a time.6. Does motion sensor have camera?Most smart security cameras are motion sensor cameras. This means that they have a smart sensor built-in – and that's the key to your smart camera always being ready to record when something happens.7. What is the difference between PIR and motion sensor?As the name implies, motion sensors detect moving objects outside or even inside your home. They are often tied to lights, alarms, security cameras, and most recently, smart doorbells. ... PIR or Passive Infrared motion sensors are designed to reliably detect people, large pets & other large warm moving objects. 

Introduction The laser displacement sensor is a device that uses laser technology for measuring. It consists of a laser, a laser detector and a measuring circuit. It is a new type of measuring instrument. For example, it can accurately measure the position and displacement of a object in a non-contact method.The laser has the excellent characteristics of good straightness, so the same laser displacement sensor has higher accuracy than the known ultrasonic sensor. However, the laser generating device is relatively complex and large in size. Therefore the application range of the laser displacement sensor is strict. Catalog Introduction Ⅰ Basic Working Principle 1.1 Measurement Objects 1.2 Measurement Methods Ⅱ Measurement Applications in Product Line Ⅲ Laser Displacement Sensors Advantages Ⅳ Alternative Types of Laser Displacement Sensor Ⅴ Laser Displacement Sensors Suppliers Ⅵ FAQ Ⅰ Basic Working Principle 1.1 Measurement Objects The laser beam emitted by the laser diode is irradiated to the surface of the object to be measured, and the reflected light passes through a set of lenses and is projected onto the photosensitive element matrix. The photosensitive part can be a CCD(charge-coupled device), CMOS(complimentary metal oxide semiconductor) or a PSD(position-sensitive detector) element. And the intensity of the reflected light depends on the surface characteristics of the measured object. The laser displacement sensor can also measure thickness, vibration, distance, diameter and other geometric quantities of the detected object. displacement sensor working state" width="294" height="222" /> Figure 1. Laser Displacement Sensor Working State 1.2 Measurement Methods According to the measurement principle, there are laser triangulation method and laser echo analysis method. The former method is generally suitable for high-precision and short-distance measurement, while the latter method is used for long-distance measurement. The following are the details of there methods.🔺Triangulation MethodThe simplest triangular displacement measurement system is to emit a beam of light from the light source to the surface of the object, and observe the position of the reflection point through imaging in the other direction, so that the displacement of the object can be detected. Since the incident and reflected light form a triangle, this method is called triangulation. According to the relationship between the angle between the incident light and the surface of the object to be measured, it can be divided into direct type and inclined type.The light emitted by the laser, after being focused by the condenser lens, is vertically incident on the surface of the measured object, and the movement of the object or the surface change causes the incident light spot to move along the incident optical axis. Receive the scattered light from the incident point of the lens and image it on the sensitive surface of the position detector (such as PSD, CDD) of the light spot. However, the laser beam of the sensor is perpendicular to the measured surface. So there is only one accurate focus position, and the images at the other positions are in different degrees of high focus state. In addition, high focus will cause the dispersion of the image point, thereby reducing the measuring accuracy. Figure 2. Light Path (direct-injection type) In order to improve accuracy, θ1 and θ2 must meet: tgθ1=Utgθ2In the formula, U is the lateral magnification. At this time, the side points within a certain depth of field can be imaged on the detector in focus to ensure accuracy.If the displacement of the light spot on the imaging surface is x', using the proportional relationship between the sides of similar triangles. The displacement of the measured surface can be obtained according to the following formula: In the formula, α is the distance from the intersection of the laser beam optical axis and the receiving optical axis to the front main surface of the receiving lens, and b is the distance from the rear main surface of the receiving lens to the center point of the imaging surface. θ1 is the angle between the optical axis of the laser beam and the optical axis of the receiving lens, and θ2 is the angle between the measured normal line and the optical axis of the receiving lens. Figure 3. Light Path (inclined type) The light emitted by the laser is incident on the measured surface at a certain angle with the normal direction of the measured surface, and the scattered light or reflected light of the measured surface of the light spot is also received by the receiving lens. The conditions should be satisfied at: tg(θ1+θ2)=Utgθ3If the image of the light spot moves x'on the sensitive surface of the detector, using the proportional relationship of similar triangles, the moving distance of the object surface along the normal direction is: Where, θ1 is the angle between the optical axis of the laser beam and the normal of the measured surface. θ2 is the angle between the optical axis of the imaging lens and the normal of the measured surface. θ3 is the angle between the optical axis of the detector and the optical axis of the imaging lens. The laser transmitter shoots the visible red laser light to the surface of the object to be measured through the lens. The laser light scattered by the surface of the object passes through the receiver lens and is received by the internal CCD linear camera. According to different distances, the camera can be set at different angles to trace this light spot. Based on this angle and the known distance between the laser and the camera, the digital signal processor can calculate the distance between the sensor and the measured object.And meanwhile, the position of the light beam at the receiving element is processed by analog and digital circuits, and the corresponding output value is calculated by the microprocessor analysis. Finally, the standard data signal is output proportionally in the analog window set by the user. If the switch output is used, it will be turned on within the set window and turned off outside the window. In addition, the analog quantity and the switch quantity output can set up the detection window independently.The maximum linearity of the laser displacement sensor adopting the triangulation method can reach 1um, and the resolution can reach the level of 0.1um. For example, the ZLDS100 type sensor can achieve high resolution of 0.01%, high linearity of 0.1%, high response of 9.4KHz, and can adapt to harsh environments. 🔺The Echo AnalysisThe laser displacement sensor uses the principle of echo analysis to measure the distance to achieve a certain degree of accuracy. The inside of the sensor is composed of a processor unit, an echo processing unit, a laser transmitter, and a laser receiver. The laser displacement sensor emits one million laser pulses per second through the laser transmitter to the detection object and returns to the receiver. The processor calculates the time required for the laser pulse to meet the detection object and return to the receiver to calculate the distance. The output value is the average output of thousands of measurement results. It is measured by the so-called pulse time method. The laser echo analysis method is suitable for long-distance detection, but the measurement accuracy is lower than that of the laser triangulation method, and the farthest detection distance can reach 250m. Figure 4. Laser Displacement Sensor Application Ⅱ Measurement Applications in Product Line Laser displacement sensors are often used to measure physical quantities such as length, distance, vibration, speed, and orientation, and can also be used for flaw detection and atmospheric pollutant monitoring.1) Size determinationPosition identification of small parts, monitoring of the presence of parts on the conveyor belt, detection of material overlap and coverage, control of the robot position (tool center position), device status, device position (through small holes), liquid level monitoring, thickness measurement, vibration analysis, crash test measurement, automobile related test, etc.2) Thickness Measurement of Metal Flakes and Thin PlatesThe laser sensor measures the thickness of a thin metal sheet (thin plate). Detection of changes in thickness can help find wrinkles, small holes or overlaps to avoid machine malfunctions.3) Simultaneous MeasurementGetting more values includes angle, length, inner and outer diameter eccentricity, conicity, concentricity and surface profile.4) Stuff Length MeasurementPut the measured stuff on the conveyor belt at the designated position, the laser sensor detects the it and measures it simultaneously with the triggered laser scanner, and finally obtains the length.5) Inspection of UniformityPlace several laser sensors in a row in the tilt direction of the workpiece to be measured, and directly output the measurement value through one sensor. In addition, you can also use a software to calculate the measurement value and read the result according to the signal or data.6) Inspection of Electronic ComponentsUse two laser scanners to place the component under test between them, and finally read the data through the sensor to detect the accuracy and completeness of the component size.7) Inspection of Filling Level on the Production LineThe laser sensor is integrated into the manufacturing of the filling product. When the product passes the sensor, it can be detected whether it is full. The sensor uses the extended program of the laser beam reflection surface to accurately identify whether the filling product is qualified and the quantity of the product.8) Measuring the Straightness of the ObjectFirst, 2-3 laser displacement sensors are needed to perform combined measurement. Then install them on a straight line parallel to the production line, and determine the distance between the three laser displacement sensors according to the measurement accuracy you need. Finally, you need to make this object move in a direction parallel to the installation line.When the production line and the sensor installation line are parallel, the greater the difference between the distances measured by the three sensors, the worse the straightness of the object, and the smaller the difference between the distances measured by the three sensors, indicating the straightness of the object. A straightness percentage can be established based on the length of the object and the distance between the three sensors, so as to obtain a quantified signal output, which has got the quantified signal output of detecting the object straightness. Figure 5. Light Receiver of Laser Displacement Sensor Ⅲ Laser Displacement Sensors Advantages 1) High Resolution and RepeatabilityEven in a larger working range, the sensor can still maintain a higher resolution and repeatability.2) Stable PerformanceThe sensor is less affected by the material and surface characteristics of the measured object, and it can directly measure the highly reflective, diffuse reflective and rough surfaces of different materials without spraying developer powder (Except for a few special materials).3) Measurement of Holes and Complex Geometric SurfacesThe coaxiality of the laser sensor enables high-precision measurement of deep holes, narrow slots, grooves and blind holes.4) Large Measurable AngleThe maximum measurable angle range of the laser sensor is 170° (±85°) in space. This technology enables the sensor to truly restore every minute detail of the complex surface of the measured object without causing any damage to the measured object.   Ⅳ Alternative Types of Laser Displacement Sensor 1) Eddy Current Displacement SensorResolution: The maximum resolution of the eddy current sensor can reach 0.1um, which is basically equivalent to the laser displacement sensor.Linearity: The linearity of the eddy current sensor is generally low, about 1% of the range, and the high-end laser displacement sensor is generally 0.1%.Measurement Conditions: The eddy current sensor requires the measured object to be a conductor and non-magnetic, that is, a non-magnetic conductor, such as aluminum, copper, etc., The laser displacement sensor is suitable for whether the measured object is magnetic or conductive. There are intersections between the two.2) Capacitive Displacement SensorThe accuracy of capacitive displacement sensors is very higher than laser displacement sensors, but the range of them is very small and generally less than 1mm, and the range of laser displacement sensors can be up to 2m.3) Fiber Optical Displacement SensorThe measurement principle of the fiber optical displacement sensor is measuring the change of the light flux and light intensity reflected on the surface of the object due to the displacement. And the probe is composed of two parts: a transmitting fiber and a receiving fiber. For the displacement and vibration of small objects, the conventional non-contact displacement sensor is limited by the reflection area and the measuring result is not ideal, while the optical fiber displacement sensor can be made into a very small probe (minimum 0.2mm diameter). What’s more, it can also be made into a form of linear transmission and reception. The displacement value can be calculated by measuring the degree of obstruction of the optical fiber during the displacement process. The accuracy can reach 0.01um, and the range can be up to 4mm. Figure 6. Fiber Optical Displacement Sensor Ⅴ Laser Displacement Sensors Suppliers Suppliers IFM Efector, Inc. MTI Instruments, Inc. Kinequip, Inc. LMI Technologies Inc. Mod-Tronic Instruments Limited Digi-Key Micro-Epsilon Diamond Technologies, Inc. Wenglor sensoric LLC Ergonomic Partners Automation Products Group, Inc. Schmitt Industries, Inc. Polytec, Inc. Baumer Ltd. Limab Rockwell Automation Baumann Machinery RIEGL USA, Inc. Linear Measurement Instruments Corp. Steven Engineering Zygo Corporation PICS INC Industrial Controls Finch Automation   Ⅵ FAQ 1. What is laser displacement sensor?The principle of laser displacement sensor ranging is a method where triangulation is applied by combining the emitting element and the position sensitive device (PSD) to perform ranging (detecting the amount of displacement). ... The laser light is focused through the emitting lens and projected on an object. 2. How does a displacement sensor work?A Displacement Sensor measures and detects changes (displacement) in a physical quantity. The Sensor can measure the height, width, and thickness of an object by determining the amount of displacement of that object. A Measurement Sensor measures the position and dimensions of an object. 3. Which sensor is used to measure the displacement?Inductive sensors – this technology uses alternating currents and is used to measure linear displacement. 4. Where are displacement sensors used?A displacement sensor (displacement gauge) is used to measure travel range between where an object is and a reference position. Displacement sensors can be used for dimension measurement to determine an object's height, thickness, and width in addition to travel range. 5. What are the types of displacement sensors?Displacement Sensor Types:Linear Displacement SensorsRotary Displacement SensorsEncodersCable Extension TransducersMembrane Potentiometers 6. Which laser sensor is used for measuring very long distances?LDM301 laser distance sensor series – fast measurement of long distances. The laser distance sensors of the LDM301 series use a measured time-of-flight principle to measure distances of 300 m for natural surfaces and 3,000 m for reflective surfaces. 7. What are the different laser sensors?The different types of laser sensors include charge-coupled devices (CCD), complimentary metal oxide semiconductors (CMOS), position-sensitive detectors (PSD), and photoelectric sensors. 8. How do laser position sensors work?The laser emits a laser beam to the target as shown above. The light reflected off the target is concentrated by the receiver lens and forms an image on the light receiving element. When the distance changes, the concentrated light reflects at a different angle and the position of the image changes accordingly. 9. How can sensors be used to detect objects?Ultrasonic sensors use sound waves to detect objects. Most ultrasonic sensors detect objects and measure distance by listening for the return echo of an emitted sound wave reflecting off of a target or background condition. 10. How do position sensors work?In Hall-effect position sensors, a moving part is linked to a magnet housed with a sensor shaft thereby forming a Hall element. With the movement of the body or its part the magnet also moves which leads to the formation of magnetic field and hence Hall voltage.

Introduction Linear Displacement Sensor, also called Linear Transducer or Linear Potentiometer Sensor, is a device used to monitor and measure linear position, which convert mechanical physical quantities into electrical signals. Linear potentiometer is a type of variable resistance sensor, designed to measure the displacement of a slider or wiper in a linear direction. Also known as a slider or pot, linear potentiometers produce a changing rate of resistance, dependent on the position of a slider or wiper. LVIT Linear Position Sensor Technology Catalog Introduction Ⅰ Linear Displacement Sensor Working Principle Ⅱ Linear Potentiometer Sensor Design Parameters Ⅲ Linear Transducer Applications Ⅳ Linear Displacement Sensor Types Recommendation Ⅴ Linear Potentiometer Sensor Installation Ⅵ Linear Transducer Operating Requirements Ⅶ Linear Displacement Sensor Use Matters Ⅷ FAQ Ⅰ Linear Displacement Sensor Working Principle The function of the linear displacement sensor is to convert the linear mechanical displacement into an electrical signal. In order to achieve this effect, the sensor slide rail is connected to a steady-state DC voltage, allowing a small current of microamperes to flow, and the voltage between the slide and the starting end is proportional to the length of the slide. Using the sensor as a voltage divider can minimize the requirements for the accuracy of the total resistance of the sliding rail, because the resistance change caused by the temperature change will not affect the measurement result. The linear displacement sensor is actually a sliding rheostat. Using the sensor as a voltage divider can minimize the requirements for the accuracy of the total resistance of the sliding rail, because the resistance change caused by the temperature change will not affect the measurement result. Figure 1. KTC 300mm Linear Displacement Sensor Ⅱ Linear Potentiometer Sensor Design Parameters For the general linear displacement sensor:Wear resistance life: >100X106 timesLinear accuracy error: <0.05%Repeatability error: <0.005mmMaximum moving speed: 10m/sImpact factor: IEC 68-2-29:1968 50gVibration factor: IEC 68-2-6:1982 20gMaximum allowable voltage: DC60V/5KΩ～20KΩ; DC36V/2KΩ～4KΩ; DC24V/1KΩTemperature drift coefficient: <1.5ppm/℃ Figure 2. KTR-75mm Linear Displacement Transducer Ⅲ Linear Transducer Applications 1) KTC, KTM, LS tie rod structure is a general structure, with optional pull ball universal head or universal head, can reduce the adverse effects caused by the installation of non-neutral. They are suitable for injection molding machines, textile machinery, woodworking machinery, etc.2) KPC and KPM fixed belts at both ends are hinged and sporty, suitable for swinging, and in measurement systems where the sensor body cannot be fixed, and the sensor will move with the measurement movement.3) KTF and KFM slider types are suitable for the application of the smallest installation length size. With the extension arm, it can eliminate the adverse effects of installation misalignment.4) KTR type is a miniature self-recovery rod structure, no need to tow and install.5) KPF type can also detect the internal displacement of the cavity. Figure 3. KPM Linear Displacement Sensor Ⅳ Linear Displacement Sensor Types Recommendation 🔺Tie Rod TypeUniversal drawbar conductive plastic film series, effective stroke 75mm ~ 1250mm, 4mm buffer stroke at both ends, precision 0.05%~ 0.04%FS. The surface of the shell is anodized, anti-corrosion.Built-in conductive plastic measuring unit, no temperature drift, long life, and automatic electrical grounding function. The sealing grade is IP67, DIN430650 standard plug and socket, which can be applied to most general occasions.The tie rod ball joint has 0.5mm automatic centering function, and the allowable extreme movement speed is 10m/s.🔺Sliding TypeGeneral-purpose slider conductive plastic film series, effective stroke 75mm～3000mm, 4mm buffer stroke at both ends, precision 0.05%～0.02%FS. The surface of the shell is anodized, anti-corrosion.Built-in conductive plastic measuring unit, no temperature drift, long life, and automatic electrical grounding function. The sealing level is IP54 (IP57 when installed downwards), DIN430650 standard plug and socket, which can be used in most general occasions, especially the length direction is limited, the alignment is difficult.The tie rod with the ball head has 10mm automatic correction function, and the allowable limit motion speed is 10m/s. Figure 4. KPC Linear Displacement Sensor Ⅴ Linear Potentiometer Sensor Installation 1) The installation of the linear displacement sensor should balance two ends. Do not tighten the fixing bracket screws before the limit position is determined. The linear displacement sensor fixing bracket screws can be locked after adjusting the stroke.2) The pull-ball universal head of the tie-rod displacement sensor allows a centering deviation with a radius of 1mm. Of course, the shorter the specification, the smaller the centering deviation is recommended.3) After fixing the linear displacement sensor, when retracting the tie rod, the cylindrical body of the universal ball head should be able to have gaps in the four radial directions. Or adjust the mounting position of the universal head or the mounting bracket position near the extended end.4) If there is a big misalignment when the pull rod is pulled out, adjust the mounting bracket near the end of the plug. This can be used as an auxiliary review method.5) The mounting rod of the pull ball universal head and the pull rod are allowed to tilt at an angle of 12°. However, if the centering deviation and tilt deviation are both large during installation, the stability and service life of the electronic ruler will be affected. So further adjustment is required.6) The slider electronic ruler can reduce the workload of adjusting the neutrality, but the auxiliary extension rod cannot be cancelled. Because the stability and service life due to the poor neutralization will occur, and even damage the sensor.7) After all adjustments are made, tighten the mounting screws to make the grounding resistance less than 1. Measure the resistance between the cover screw of the potentiometer sensor and the mounting bracket with a multimeter in the 200 block.8) When using a four-wire system or wiring with a shielded wire, the grounding end of the linear potentiometer should be connected, and the fourth end or shielding wire should be grounded at the end of the electric control box correctly. Figure 5. KTM Linear Displacement Sensor Ⅵ Linear Transducer Operating Requirements 🔺The supply voltage should be stable.Industrial power supply requires ±0.1% stability. For example, the reference voltage is 10V, and the fluctuation of ±0.01V is allowed under the fluctuating voltage. Otherwise, it will cause the displayed trap to fluctuate. 🔺Prevent electrostatic interference.Electrostatic interference and FM interference can easily make the digital display of the linear displacement sensor jump. Separate the strong current line of the equipment from the signal line of sensor in a wire duct. The potentiometer should use a grounding support, and its shell (the resistance between the end cover screw and the support should be less than 1Ω) must be well grounded. The signal line should be shielded and well grounded where at one end of the electrical box.In the case of electrostatic interference, the voltage measurement of the general multimeter is normal, but it shows the digital beating, even the phenomenon is the same when the high-frequency device is interfered. To verify whether it is electrostatic interference, use a power cord to short-circuit the cover screw of the sensor with a certain point of metal on the machine. However, it is difficult to eliminate high-frequency interference by the above-mentioned methods, which occurs frequently in robots and inverters. Stopping the robot or the inverter power saver can test it. 🔺WiringLines "1" and "3" are power lines, and "2" is the output line. Once the above line is connected wrongly, there will be large linear errors, resulting in poor control accuracy, and display bounce easily. 🔺The power supply capacity should be sufficient.If the power supply capacity is too small, the following situations are likely to occur: the mold clamping movement will cause the display of the glue injection ruler to jump, or the melt movement will cause the display of the mold clamping potentiometer sensor to fluctuate. Especially when the power supply of solenoid valve drive power supply is combined with the sensor, the above-mentioned situation is prone to occur. In severe cases, the voltage fluctuation can be measured with the voltage file of a multimeter. If the problem cannot be solved, even if the electrostatic interference and high-frequency interference are eliminated, the neutrality is also bad. At this time, you can check the power supply efficiency. 🔺Installation angleThe angle tolerance is ±12°, and the parallelism tolerance is ±0.5mm. If both are too large, it will cause the display number to jump. In this case, the angle and parallelism must be adjusted. 🔺Prevent short circuit.During the working process of the displacement sensor, the data is regularly displayed at a certain point or no data. In this case, it is necessary to check whether the connection line insulation is damaged and the ground short circuit caused by regular contact with the machine's metal casing. 🔺Avoid aging.For the linear displacement sensor that has been used for a long time, the seal is aging, there may be a lot of impurities, such as oil and water mixture, which affect the contact resistance of the brush, and cause the display number. It can be considered as the early damage of sensor. Figure 6. KTF Linear Displacement Sensor Ⅶ Linear Displacement Sensor Use Matters 1) If the potentiometer sensor has been used for a long time, and the seal has been aging, there are a lot of impurities mixed in, and the water mixture and oil will seriously affect the contact resistance of the brush, which will cause the displayed number to jump continuously. At this time, it can be said that the electronic ruler of the linear displacement sensor has been damaged and needs to be replaced.2) If the capacity of the power supply is small, there will be many situations. Therefore, the power supply should have sufficient capacity. Because insufficient capacity will cause the following situation: The movement of the melt will change the display of the sensor to cause the fluctuations,  resulting in a large error in the measurement result.If the driving power of the solenoid valve and the power supply of the linear displacement sensor are at the same time, the above situation is more likely to occur. In serious cases, the voltage range of the multimeter can even measure the relevant fluctuations of the voltage. If the situation is not caused by high-frequency interference, electrostatic interference, or insufficient neutrality, then it may be caused by the small power supply.3) FM interference and electrostatic interference may cause the digital scale of the linear displacement sensor to jump. The signal line of the sensor and the strong current line of the equipment should be separated from the wire duct. Use the grounding support to have good contact with the ground. The signal wire needs to use a shielded wire, and a section of the electrical box should be grounded to the shielded wire.If there is high-frequency interference, the voltage measurement with a multimeter will usually display abnormally. When there is electrostatic interference, the situation is the same as that of high-frequency interference. To prove whether it is electrostatic interference, you can use a power cord to short-circuit the cover screw of the sensor with some metal on the machine. As long as it is short-circuited, the e-interference will be eliminated immediately. However, if you want to eliminate high-frequency interference, it is difficult to use the above method. Frequency-conversion power savers and robots often have high-frequency interference, so you can try to stop them to verify the interference.4) The power supply voltage must be stable. The industrial voltage needs to meet the stability of ±0.1%. For example, if the reference voltage is 10V, a fluctuation of ±0.01V can be allowed. If it is not, it will cause a display fluctuation. But if the amplitude of the display fluctuation at this time does not exceed the amplitude of the fluctuation voltage, then the potentiometer sensor is normal.5) As for the linear displacement sensor installation, the parallelism can be allowed to have an error of ±0.5mm, and the angle can be allowed to have an error of ±12°. However, if both are too large, then the display number will be bounced. So the parallelism and angle must be adjusted.6) During the connection process, be sure to pay more attention, the wires of the potentiometer sensor cannot be connected wrongly.   Ⅷ FAQ 1. What is a linear displacement sensor?A linear displacement sensor is a device used to monitor and measure linear position. They can also be called Linear Position Sensors or Linear Transducers. They are available in different sizes to measure different stroke lengths.   2. How does a linear displacement sensor work?Linear displacement transducers are linear sensors that work on the magnetostrictive principle, whereby a torsional strain pulse is induced in a specially designed magnetostrictive waveguide by the momentary interaction of two magnetic fields.   3. What is the linear displacement?Therefore; “Linear Displacement” can be defined as the movement of an object in a linear fashion along a single axis in a straight line, for example; from side to side or up and down. ... Linear Displacement is usually measured in millimetres or inches and has a positive and negative direction.   4. What are linear sensor potentiometers?A linear potentiometer is a type of position sensor. They are used to measure displacement along a single axis, either up and down or left and right. Linear potentiometers are often rod actuated and connected to an internal slider or wiper carrier.   5. What is the difference between linear potentiometer and rotary potentiometer?This potentiometer is similar in function to the rotary potentiometer. The only difference between these two, as the name suggests, is the linear motion of the knob, instead of rotary, for adjusting the resistance.   6. How does a potentiometer sensor work?Potentiometers work by varying the position of a sliding contact across a uniform resistance. ... A potentiometer has the two terminals of the input source fixed to the end of the resistor. To adjust the output voltage the sliding contact gets moved along the resistor on the output side.   7. What does a potentiometer sensor measure?A potentiometer sensor measures the distance or displacement of an object in a linear or rotary motion and converts it into an electrical signal.   8. How does a potentiometer measure displacement?To measure the displacement of the body, this body, which is moving, is connected to the sliding element of the potentiometer. As the body moves, the position of the slider located on the potentiometer also changes so the resistance between the fixed point and the slider changes.

IntroductionAs we all know, Tire Pressure Sensor is a small programmable electronic device for driving safety. So what is the role of car tire pressure sensor? Just to prevent car accidents? Of course more than that, it can also extend the service life of the tires and even reduce the wear and tear of the suspension system. So this sensor should not be underestimated. Therefore, what exactly is the tire pressure sensor monitoring? How does it send signals to the vehicle controller? What is the difference between built-in and external sensor? Here gives a detailed introduction.TPMS Tire Pressure Monitoring Systems InstallationCatalogIntroductionⅠ Tire Pressure Sensor Working PrincipleⅡ Tire Pressure Sensor LocationⅢ Types of Tire Pressure Sensor Comparisons3.1 Original Second-generation Tire Pressure Sensors3.2 OEM Tire Pressure Sensors3.3 HUF TPMS Sensors3.4 Second-generation Tire Pressure SensorsⅣ Tire Pressure Sensor FaultsⅤ Tire Pressure Monitoring System ResetⅥ FAQⅠ Tire Pressure Sensor Working PrincipleThe tire pressure sensor signal is sent to the antenna receiver by sending a wireless signal of 433MHz or 355MHz, and the receiver sends the tire pressure data to the BCM (body control module) through the LIN (serial communication network), and finally compares with the BCM preset tire pressure data. If the tire pressure is too low, BCM will send a signal to the meter through the gateway via the high-speed CAN (serial communication protocol), showing the result. With the development of technology, the tire pressure sensor fully supports high-definition accurate monitoring of tire temperature, tire pressure and battery status to ensure driving safety at all times. The general-purpose tire pressure sensors on the market can replace all original sensors, copy the data of the original tire pressure sensors, and can repeat programming indefinitely.Figure 1. Tire Pressure Sensor Working PrincipleInstalling a tire pressure sensor is a direct type of tire pressure monitoring. Use the sensor installed in each tire to directly measure the tire pressure, then use the wireless transmitter to send the pressure information to the central receiver module, finally display the tire pressure data. When the tire pressure is too low or when there is a gas leak, the system will alarm automatically.In addition, there is also indirect tire pressure monitoring. Its working principle is: when the air pressure of a certain tire decreases, the weight of the vehicle will make the rolling radius of the tire smaller, causing its speed to be faster than other wheels. By comparing the rotational speed between the tires, in order to achieve the purpose of monitoring the tire pressure, the indirect tire alarm system actually relies on the tire's rolling radius to monitor the air pressure. Ⅱ Tire Pressure Sensor LocationThe tire pressure monitoring sensor is installed on the tire, usually at the valve position. The tire pressure monitoring display is usually placed on the center console. A lot of electronic devices are installed in the middle of the center console, which has a certain impact on radio frequency interference, especially the electronic eye. The tire pressure sensor can be divided into built-in type and external type according to the location where it is installed.The following is a display drawing of the location of the tire pressure sensor in a car:Figure 2. Tire Pressure Sensor Location Display Drawing1: Right-front wheel pressure monitoring sensor2: Central information display (can display tire inflation pressure info)3: Right-rear tire pressure monitoring sensor4: Remote control signal receiver5: Left-rear tire pressure monitoring sensor6: Combination instrument7: Dynamic stability control system8: Left-front tire pressure monitoring sensor🔺External Tire Pressure SensorFigure 3. External Tire Pressure SensorUsually, some of the original tire pressure sensors that the car is equipped with can display the current tire pressure, while others only give an alarm when the tire is out of air. For the external tire pressure sensor, the valve core has not played much role.The external tire pressure sensor is very simple to replace the battery. The battery can be opened by disassembling it with a wrench or other tools. The service life of the external battery is much shorter than that of the built-in battery due to structural design.🔺Built-in Tire Pressure SensorFigure 4. Built-in Tire Pressure SensorThe built-in sensor has obvious feature, that is, it can avoid being stolen and external interference, and it can be used for a longer time.But why can the original car tire pressure monitoring battery last for 8-10 years, while the latter can only be used for about 5 years? This is mainly due to the different working principles.In the original car, the tire pressure sensor is usually in a dormant state after the vehicle is stationary for 30 minutes. When the vehicle speed exceeds 30KM/hour, the sensor sends a signal to the receiver once a minute. The transmission frequency is about 433MHz, and the additional tire pressure sensor will emit a signal every 5 seconds or so when the tire rotates. So it is very power-consuming to use it.For driving safety, of course, the shorter the signal transmission interval, the better. However, tire leaks are generally slow. If it is a puncture, the tire pressure sensor will not play any role. Therefore, the sending interval of 1 minute is very reasonable, which can greatly improve the battery life.The principle is not complicated whether it is built-in or external sensors. The sensor sends the tire pressure data to the receiver via a wireless signal, and then displays it. Based on the above analysis of various tire pressure sensors, we can get such a result, that is, the stability of the original sensor is greater than that of the later installation. The built-in type is better than the external type in terms of use time and safety. Ⅲ Types of Tire Pressure Sensor Comparisons3.1 Original Second-generation Tire Pressure SensorsThe third-generation tire pressure of the original factory has been officially certified by Audi, with complete packaging and certificates. It is the most formal product. The service life of the qualified product of the original factory is more than six years.Advantages: High production standards. The various accessories used, including button batteries, have strict standards, and the accuracy of tire pressure data and transmission stability are very reliable.Disadvantages: After a lengthy supply chain, the cost rises. For example, a kind of tire pressure sensor is ordered from somewhere: the price is 400+, and the installation also requires modules, gas nozzles, and wiring harnesses, therefore, the price must be increased. 3.2 OEM Tire Pressure Sensors (off the official assembly line)Everyone knows that each OEM has its own dedicated supporting supplier, and the product will be installed and used in the car after very strict testing when it arrives at the OEM. This process will screen out a batch of products that do not meet the requirements of the OEM. , It may also be that the production date is too long. When the battery power does not meet the original factory requirements, it is treated as industrial waste.Advantages: Cheap priceDisadvantages: Sensor quality cannot be guaranteed. The production date is too long, the product does not have any packaging, the appearance and function (accuracy, sensitivity, etc.) cannot be guaranteed, and there is no after-sales service generally. 3.3 HUF TPMS SensorsThe comparison chart between HUF and the original tire pressure sensor shows that except for the different product codes, everything else is the same.Figure 5. Tire Pressure Sensor ComparisonAdvantages: The production standard is the same as the original product, except for the difference in marking and packaging. Because there is no Audi supply channel, the price is lower than the original product. Except that, the quality can be guaranteed by independent sellers.Disadvantages: Unofficial channels and no certificates. 3.4 Second-generation Tire Pressure SensorsThe sub-factory tire pressure sensor is a highly modeled product. Some small manufacturers have developed closely based on the original product. There are many brands and types of products. The appearance of this type of product is quite different from the above three types.Advantages: Cheap price.Disadvantages: The production standard is low, and the tire pressure data accuracy, transmission stability, and service life cannot be guaranteed. Although it can be used when installed, it is easy to have problems. Ⅳ Tire Pressure Sensor FaultsHow do I know if my tire pressure sensor is bad? The tire pressure sensor faults may be caused by the sensor running out of power, the sensor signal failure, and the sensor circuit failure. Due to different car usage conditions, you can check according to the following failure reasons:1) First of all, the air pressure is not high. If it is, the tire pressure needs to be reset; if not, it is a monitoring failure, but this possibility is small. Generally, the tire sensor is faulty, which will cause the brake system to turn the TPMS (tire pressure monitoring system) light on, and you can go to the repair shop to reset.Figure 6. Tire Pressure Sensor Light2) The Volkswagen series cars can supplement the standard air pressure, and then press the tire pressure monitoring button for a few seconds to reset. Other car models can use the decoder to reset or automatically reset after driving a certain distance when the standard air pressure is supplemented.3) The vehicle tire pressure is strictly the air pressure inside the tire, so the height of the tire has an important influence on the performance and power of the car. When you test a tire pressure sensor failure, you can check it.4) If the tire pressure sensor is out of power, it is easy for the tire pressure to be falsely reported. At the same time, the tire pressure value may be very unstable from high to low, and the brightness of the tire pressure display will decrease. When these problems occur, you can try to replace the tire pressure sensor battery to test.Over time the (Tire Pressure Monitoring System) TPMS sensors can go bad or the batteries can go dead. Here shows you how to replace TPMS sensors at home without a tire machine. Just look at the following video:How To Replace TPMS (Tire Pressure Monitoring System) Sensors? Ⅴ Tire Pressure Monitoring System Reset1) Press the button at the lower right corner of the multifunction steering wheel to calibrate the tire pressure monitoring system. You need to press the operating button to select "Vehicle Setting".2) Press the SEL/RESET button, the tire pressure monitoring system calibration will appear on the display.3) Press the SEL/RESET button, the display will switch to the personalized setting interface, and then select "Calibration".4) Press the SEL/RESET button, the "Calibration Start" message will appear on the multi-information display, and disappear after two seconds.Figure 7. Car Tire Pressure Sensors Ⅵ FAQ1. What does it mean when tire pressure sensor fault comes on?The “tire pressure sensor fault” message is an indication that there is a problem with the tire pressure monitoring system. ... If the tire is overinflated or underinflated, this could cause damage to the tire and/or hazardous driving conditions. 2. How much does it cost to fix a tire pressure sensor fault?Generally speaking, the TPMS sensor replacement cost is going to fall somewhere between $230 and $750 in most cases. And unlike some other auto repairs, it's the parts, not the labor, that are going to get you. TPMS sensors can cost anywhere from $180 to $680 alone. 3. Can you drive with a bad tire pressure sensor?No, driving with the TPMS Light on is not safe. It means one of your tires is underinflated or overinflated. ... This can cause undue wear on the tire, potentially lead to a tire failure, and cause a blowout dangerous to you and other drivers on the road. 4. How do I test my TPMS sensor?It is important check the TPMS system before working on a customer's vehicle. Using a TPMS diagnostic tool, select the vehicle's make, model and year manually – or for faster service, scan the vehicle's VIN barcode located on the placard on the vehicle doorjamb to read the sensor information. 5. How long do tire pressure sensors last?The lithium ion batteries inside tire pressure sensors may last anywhere from five to 10 years. Five to six years is a more typical lifespan for older TPMS sensors. The lithium ion batteries inside TPMS sensors may last anywhere from five to 10 years. 6. Can you drive without tire sensors?Yes you can. If you are in canada, there is no law about tpms (tire pressure monitoring system), so there is no problem to drive without it. In USA, this is forbidden. Over this, you will have a light on in your dash if you wheel don't have sensor, but no other issue. 7. How much should it cost to replace a tire sensor?The service kit costs $5-$10 per wheel on most vehicles. A special TPMS tool and additional time are also needed to check and reset the sensor system. In the event pressure sensors need to be replaced, the cost ranges from $50-$250 each depending on vehicle type. 8. How do you fix a tire pressure sensor?Press the TPMS reset button and hold it until the light blinks three times, then release it. Start the car and let it run for 20 minutes to reset the sensor. You'll usually find the tire pressure monitor reset button beneath the steering wheel. Check your user's manual if you're having trouble locating it. 9. How do I know if my tire pressure sensor is bad?Drive for a little bit. The light should go off as the sensor reads the new pressure levels. If the light stays on, you should have us check your tires for a leak or another issue that may not be immediately visible. If the tire pressure is stable, then it could be a bad sensor. 10. Why do tire pressure sensors fail?Some tire pressure sensors have been known to fail as a result of corrosion. ... This can result in valve stems breaking off or cracking, causing the tire to go flat. Other reasons for failure include wiring faults, issues with keyless entry systems, and TPMS module failure, however these are all far less common faults. 11. Can you turn off tire pressure sensor?The U.S. Department of Transportation has mandated that all vehicles manufactured after 2008 include a tire pressure monitoring system (TPMS). Although you cannot disable the TPMS in a General Motors (GM) vehicle, you can reset the system if you recently checked your tires and inflated them properly. 12. Can I replace just one TPMS sensor?You can replace just one sensor. However, when you replace a TPMS sensor you have to "register" it on the vehicle. That is, the vehicle ECU has to be programmed to know that it has a new sensor with a new ID. 13. Is it worth it to replace TPMS sensors?The only time when the TPMS sensor replacement cost might not be worth it is when your car isn't worth much at all. If you have an older car that isn't worth a whole lot of money, paying to have bad TPMS sensors replaced might not be in your best interests. 14. Can you replace battery in TPMS sensor?Most TPMS sensors run on batteries that are built into the sensor and these batteries are not replaceable. The life expectancy of the lithium ion batteries in a TPMS sensor is anywhere from 5-10 years. ... If one of your TPMS sensors fails and needs replacement, you can replace it individually. 15. How do I get the TPMS light to go off?Drive the car at 50 mph for about 10 minutes.This should reset the sensor, and the next time you start the car the TPMS light should be off. Without starting the car, turn the key to the “On” position. Press the TPMS reset button and hold it until the light blinks three times, then release it.

IntroductionThe Temperature Sensor, a measuring instrument, uses various physical properties of a substance to convert the thermal quantity into the physical quantity, including expansion, resistance, capacitance, electromotive force, magnetic properties, frequency, optical characteristics and thermal noise. Many materials and components change with temperature, so there are quite a few materials that can be used as temperature sensors. Here are four temperature sensors in detail.Temperature Sensors ExplainedCatalogIntroductionⅠ Temperature Sensor Types Overview1.1 What is Thermocouple?1.2 What is Thermistor Sensor?1.3 What is Resistance Temperature Detector (RTD)?1.4 What is IC Sensor?1.5 Temperature Sensor Cons and ProsⅡ How to Test: Measuring IndexesⅢ FAQⅠ Temperature Sensor Types OverviewThere are many types of temperature sensors, which can be divided into contact type and non-contact type according to the measurement method; thermistor and thermocouple according to the characteristics of sensor materials and electronic components.The contact temperature sensor needs to maintain thermal contact with the measured medium, so that the two can perform sufficient heat exchange to reach the same temperature. This type of sensor mainly includes resistance type, thermocouple, PN junction temperature sensor and so on. The non-contact temperature sensor does not need to be in contact with the measured medium, but achieves the purpose of temperature measurement through the heat radiation or convection of the measured medium.Here is a detailed introduction to the commonly used four: Thermocouples, Thermistors, Resistance Temperature Detector (RTD), IC Sensor.Figure 1. Temp Sensors (Resistance Changes with Temperature)1.1 What is Thermocouple?Thermocouples are the most commonly used temperature sensors in measurement. Its main advantages are wide temperature range and adaptability to various atmospheric environments, and it is strong, low in price, does not require power supply, and is also the cheapest. The thermocouple consists of two different metal wires connected at one end. When one end of the thermocouple is heated, there is an electric potential difference in the thermocouple circuit, and the measured electric potential difference can be used to calculate the temperature.Figure 2. Metal JunctionsThe thermocouple sensor has two contacts. The measurement end (sometimes called the hot end) is where the two metals connect. The reference junction (also called the cold end) is connected to the measurement circuit. When there is a temperature difference between two ends, an mV signal proportional to the temperature difference is generated. The mV value increases with increasing temperature. The relationship between mV and temperature is non-linear.The thermocouple connector can be constructed by connecting the thermal junction to the outer sheath for grounding or ungrounding (insulating from the sheath). A grounded thermocouple responds faster, but the thermocouple will contact the processing voltage. Therefore, it is important to isolate the measurement circuit to prevent the formation of ground loops and to avoid measurement errors.Figure 3. Thermocouple for Temperature MeasurementInside the temperature component, the thermocouple is usually embedded in magnesium oxide (MgO) and a metal sheath, then insert it into the thermowell or protective tube. This helps protect the sensor from environmental pollution. When magnesium oxide is contaminated with water and salt, even thermocouples that are not grounded will eventually be grounded.As above mentioned, the relationship between voltage and temperature is nonlinear, so it is necessary to make a second measurement for the reference temperature (Tref), and use the test equipment software or hardware to process the voltage-temperature conversion inside the instrument to finally obtain the thermocouple temperature (Tx). Thermocouple is the simplest and most versatile temperature sensor, but its sensitivity is relatively low, which is easy to be affected by environmental interference signals, and the temperature drift of the preamplifier. So it is not suitable for measuring small temperature changes, that is, it is not suitable for high-accurate measurement and application.In actual use, the thermocouple measuring circuit can measure any temperature except 0°C. The measuring circuit must measure the temperature of the cold junction and restore the temperature to 0°C. This kind of electrical compensation is called cold junction compensation (or reference junction compensation). Most thermocouple measurement circuits do this.If the application requires a thermocouple instead of a thermistor, a higher-grade thermocouple is better. In addition, their cost difference is small, and high-quality wire can provide higher stability.🔺Table 1: Thermocouple Types and Application RangesThermocouple TypeApplication Range (℃ / ℉)E95-900℃ (200-1650℉)J95-760℃ (200-1400℉)K95-1260℃ (200-2300℉)N95-1260℃ (200-2300℉)R870-1450℃ (1600-2640℉)S980-1450℃ (1800-2640℉)T0-350℃ (32-660℉) 1.2 What is Thermistor Sensor?The main component of the thermistor sensor is the thermistor, which absorbs heat radiation around.Thermistors are made of semiconductor materials, mostly with a negative temperature coefficient, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor. However, the linearity of the thermistor is extremely poor and has huge effects with the production process. So the manufacturer cannot give a standardized thermistor curve.The thermistor is very small and responds quickly to temperature changes. But it needs to use a current source, and its small size also makes it extremely sensitive to self-heating errors.Figure 4. Thermistor SensorThe thermistor measures the absolute temperature on the two lines, with better accuracy, but it is more expensive than a thermocouple, and the measurable temperature range is also smaller than that of a thermocouple. A commonly used thermistor has a resistance value of 5kΩ at 25°C, and a temperature change of 1°C causes a resistance change of 200Ω. Note that the lead resistance of 10Ω only causes a negligible error of 0.05°C. It is very suitable for current control applications that require fast and sensitive temperature measurement. Small size is benefit for applications with space requirements, but care must be taken to prevent self-heating errors.Figure 5. Resistance-TemperatureThe thermistor also has its own measurement tips. With small size, it can quickly stabilize, and will not cause thermal load. However, it is not strong enough, and large currents can cause self-heating. Since the thermistor is a resistive device, any current source will cause heat on it due to power. Power is equal to the product of current squared and resistance. Therefore, a small current source must be used. If the thermistor is exposed to high heat, it will cause permanent damage. 1.3 What is Resistance Temperature Detector (RTD)?RTD is a precision temperature sensor, made of high-purity conductive metal (such as platinum, copper or nickel) or alloy. Its resistance increases with increasing temperature and decreases with decreasing temperature, similar to a thermistor. RTD is like a thermoelectric converter, converting temperature changes into voltage changes. By passing a constant temperature current through the temperature sensor, an output voltage that increases linearly with temperature can be obtained. The most suitable metal for RTD is a pure metal that remains stable within a given temperature range. The resistance-temperature change relationship is preferably linear. The larger the temperature coefficient (it is defined as the resistance change caused by unit temperature), the better, and it must be able to resist thermal fatigue and respond sensitively to temperature changes. A typical RTD has a protective sleeve and a probe. The protective sleeve is mainly used to protect the RTD from being damaged by the measured medium, which is usually made of stainless steel, carbon steel, inconel or cast iron, and its use temperature can reach 1100°C.Figure 6. Resistance Temperature Detector (RTD)It is currently the most accurate and stable sensor, and its linearity is better than thermocouples and thermistors. However, RTD is also a temperature sensor with slow response speed and more expensive price. So it is most suitable for applications that have strict requirements on accuracy, but speed and price are not critical. 1.4 What is IC Sensor?IC sensors can work in a temperature range of -55°C to +150°C, and precise one can operate at temperatures up to +200°C. It is commonly used in fitness tracking applications, wearable products, computing systems, data loggers, and automotive applications. The most common integrated IC temperature sensors are analog output devices, digital interface devices, remote temperature sensors, and those integrated ICs with thermostat functions.Figure 7. IC Sensors (Thermometer)Analog output devices (usually output voltage, but some also output current) are most like passive solutions when they need an ADC to process the output signal. Digital interface devices most often use a two-wire interface (I2C or PMBus) and have a built-in ADC. In addition to including a local temperature sensor, remote temperature sensors also have one or more inputs to monitor the remote diode temperature—they are most often placed in highly integrated digital ICs (for example, processors or field programmable gate arrays FPGA). When reached the temperature threshold, the thermostat can provide a simple alarm.Here are the details of two common types:🔺Analog Output Temperature SensorThe integrated sensor is made using silicon semiconductor integration process, so it is also called a silicon sensor or a monolithic integrated temperature sensor. It is a dedicated IC that integrates a temperature sensor on a chip and can take temperature measurement and then output analog signals. The main features of this sensor are single function (only measuring temperature), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc., which are suitable for long-distance temperature measurement, control and measurement. What’s more, non-linear calibration doesn’t required, and the peripheral circuit is simple.🔺Digital Output SensorDigital temperature sensor is the product of microelectronics technology, computer technology and automatic test technology (ATE). The intelligent temperature sensor contains temperature sensor, A/D converter, signal processor, memory (or register) and interface circuit. Some products also come with multiplexers, central controller, random access memory and read-only memory. The characteristic of the intelligent temperature sensor is that it can output temperature data and related temperature control quantities, adapts to various microcontrollers (MCU). It realizes the test function through software on the basis of hardware, and its intelligent harmony also depends the level of software development.1.5 Temperature Sensor Cons and Pros🔺Table 2: Advantages and Disadvantages of thermocouples, RTDs, thermistors and IC sensors.CriteriaThermocoupleRTDThermistorIC SensorTemperature-250℃ to +750℃-100℃ to +500℃-267℃ to +2316℃-55℃ to +200℃AccuracyBestDepends on calibrationGoodGoodLinearityGoodWorstGoodBestSensitivityLessBestWorstGoodCircuityComplexDepends on accuracy/power requirementsComplexSimplestPower ConsumptionHigh when takingLow-highLowest Ⅱ How to Test: Measuring Indexes1) Measurement accuracy: 0.01 level2) Resolution 0.1uV and 0.1mΩ3) Scan switch parasitic potential: ≤0.4μV4) Temperature range: Water tank: (room temperature +5~95)°C; Oil tank: (95 ~ 300)°C; Low & constant temperature bath: (-80 ~ 100)°C; High temperature furnace: (300~1200)°C5) Temperature control stability: better than 0.01℃/10min (oil tank, water tank, low temperature constant temperature tank); 0.2℃/min (tube type verification furnace)6) Total uncertainty: For thermocouple verification, measurement uncertainty is better than 0.7 ℃, repeatability error <0.25 ℃; For thermistor verification, measurement uncertainty is better than 50 mk, repeatability error <10 mk7) Working power supply: AC220V±10%, 50Hz, and well protected grounding.8) High temperature furnace power: about 2kW9) Constant temperature bath power: about 2kW10) Power of microcomputer measurement and control system: <500 Ⅲ FAQ1. What is temperature sensor and how it works?How do temperature sensors work? They are devices to measure temperature readings through electrical signals. The sensor is made up of two metals, which generate electrical voltage or resistance once it notices a change in temperature. ... Temperature is the most common physical measurement type in industrial applications. 2. What happens when a temperature sensor goes bad?If the coolant temperature sensor goes bad it can send a false signal to the computer and throw off the fuel and timing calculations. ... This will cause the computer to think the engine is cold, even when it is not, and as a result will use more fuel than necessary. 3. Which temperature sensor is best?The most well-known are Pt100 (with a resistance of 100 ohms at 0°C) and Pt1000 (with a resistance of 1,000 ohms at 0°C). The Pt1000 offers better accuracy and a larger tolerance to long wire lengths than the Pt100. Compared to thermocouples, resistance sensors offer better accuracy and a more linear response. 4. What is the application of 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. 5. How do I know if my temperature sensor is bad?What Signs May Signal Your Coolant Temperature Sensor May Be Failing.Poor Fuel Economy.Irregular Temperature Readings.Black Smoke from Your Exhaust.Your Engine is Overheating.Your Check Engine Light is On. 6. How important sensors are nowadays?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. 7. What should I consider when choose a temperature sensor?Several factors must be considered when selecting the type of sensor to be used in a specific application: temperature range, accuracy, response time, stability, linearity, and sensitivity. 8. What is the value range of a temperature sensor?The effective operating range is -50 to 250 °C for glass encapsulated thermistors or 150°C for standard thermistors. 9. What are the pros and cons thermocouple?Advantages and disadvantages of thermocoupleAdvantages of thermocouple: Simple working principle, Short response time, Low price, Wide temperature ranges, Rugged construction, Self-powered, Small size.Disadvantages of thermocouple: Nonlinearity, Accuracy, Interference can cause errors. Old technology, Needs calibration, Corrosion. 10. What is difference between PT100 and RTD?There is no difference a PT100 is a version of a RTD (resistance temperature detector). What is an RTD? A resistance temperature detector, also known as an RTD or resistance thermometer, is a type of temperature sensor. ... A PT100 sensor is the most common type of Resistance Thermometer (RTD).