The Kynix Blog - Sensor

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

In the future, a new sensor cable could be used to protect airports, industrial complexes and people’s yards without a great deal of expense. It registers even the tiniest changes in the Earth’s magnetic field.Plenty of things go unnoticed by our senses. One of them is the Earth’s magnetic field. Unlike migratory birds and sea turtles, we need technical aids to make use of it. Like the good old compass. It has been helping seamen navigate the seven seas since the 12th century. Sort of a primitive precursor of today’s magnetic field sensors. Then in 1832, mathematician and physicist Carl Friedrich Gauss laid the cornerstone for modern magnetic sensor technology when he developed a method for measuring both the direction and intensity of the Earth’s magnetic field.Since then, magnetic-field sensors have become quite important because they make entirely new solutions for difficult measuring tasks possible. And not just for research and industry—also for our private lives. For example, they help determine location and position in our smartphones. And with Apps such as Telemeter 11th, they even turn a digital Swiss knife into a metal detector.Magnetic burglar alarmSaarland University’s “All-round Warning Alarm” is based on a similar principle. When attached to fencing, a thin magnetic field sensor cable can tell whether the wind, a bird or wire cutters are “interacting” with the wire mesh. Buried in the ground of future traffic-guidance systems, it can tell which direction automobiles are driving. Not even smartphones or zippers can go undetected. That is because everything within a few meters that influences the Earth’s magnetic field is registered by highly sensible magnetic field sensors and transmitted to a smartphone via Bluetooth.The sensor cable is flexible and can be adapted to a wide variety of requirements, and it consumes very little electricity. It is also practically wear free, and measurements do not dependent on weather conditions. In addition, no data is stored and the sensor system has proved a hard nut for hackers to crack.The technology is based on the fact that the Earth’s weak magnetic field (approx. 50 microtesla) is always everywhere. And that every ferromagnetic object measurably disturbs this field for magnetic field sensors with sensitivities in the nanotesla range. Corresponding electronics and algorithms then determine metallic properties, size and direction of motion. Every type of “disturbance” has its own magnetic fingerprint.Magnetic field sensors for every purposeResearchers have been working a “magnetic” recognition systems for a good 15 years. As part of the development process, experiments were conducted with so-called AMR (anisotropic magnetoresistance) and GMR (giant magnetoresistance) sensors. The latter can be found in billions of read heads in hard disk drives, and the physicists who discovered them, Peter Gruenberg from Forschungszentrum Jülich and Albert Fert from Université Paris-Sud, were awarded the Nobel Prize in Physics in 2007. Both work sensors are based on the so-called magnetoresistance effect, which says that ferromagnetic materials change their resistance in a magnetic field.Burglars in a “tunnel”The first trials with the third member of the magnetoresistance team, i.e. GMI (giant magnetoimpedence) sensors, are now underway in Saarland. In this case, impedance (alternating current resistance) depends on the intensity of an applied, relatively weak external magnetic field.But that’s not all: The prototype recently introduced by Saarland University researchers uses a fourth variant, i.e. TMR (tunnel magnetoresistance) sensors, which have only been commercially available for a short time. As the word “tunnel” suggests, these magnetic field sensors make use of quantum mechanics effects. Due to their high change in resistance of 20%, TMRs are extremely interesting for a number of applications. They are provided by Sensitec(Germany), one of the partners in this project, which is sponsored by Germany’s Federal Ministry of Research.With the exception of the AMR effect, all magnetoresistance effects were discovered after 1988. In other words, this is still a relatively new, rapidly growing research sector with the prospect of extraordinary sensor solutions for various electronics sectors in the years to come. It will be interesting to see what happens! Ref:KY45-HMR3400KY45-HMC6343KY45-HMC2003

The BHA250 low-power sensor hub and BHI160 ultra-low power sensor hub from Bosch Sensortec is now in stock at distributor Mouser Electronics . Designed specifically for always-on sensor applications in smartphones running the Android operating system, the BHA250 and BHI160 enable designers to offload sensor processing from the main processor, which can reduce power consumption and extend battery life.  The sensor hubs integrate a best-in-class 3-axis MEMS accelerometer (BH250) or 6-axis gyroscope/accelerometer inertial measurement unit (BH160) with the new Bosch Sensortec digital signal processor, Fuser Core.The Fuser Core is a 32-bit floating-point microcontroller optimised to execute Bosch Sensortec's sensor fusion and activity-recognition algorithms with ultra-low power consumption — up to 95 percent less than that of other microcontrollers.The BHA250 and BHI160 are specifically designed for applications in Android smartphones — implementing a full Android sensor stack inside the devices to provide a flexible, low-power solution for always-on motion sensing and sensor data processing. In both devices, the 32-bit Fuser Core microcontroller features 96 kBytes of ROM, including the BSX sensor fusion library, and 48 kBytes of RAM for additional drivers, local data buffering, or feature updates.The devices provide up to three general-purpose input/outputs (GPIOs) and a high-speed I2C interface with data rates up to 3.4 MBit/s for power-efficient data transfer.They meet the requirements of smartphones, wearables, and other applications that demand highly accurate, real-time motion data at very low power consumption.Mouser also offers corresponding shuttle boards for the sensor hubs. Both the BHA250 shuttle board and BHI160 shuttle board, available to order from Mouser, include four external magnetometers that can be connected to the sensor hubs using the available jumpers on the PCB.The shuttle board allows easy access to the sensor‘s pins via a simple socket and can be plugged into the Bosch Sensortec Application Board. Ref:KY45-AD22293ZKY45-SS16-3KY45-TLE4998P3 

Chip scale high precision measurements of physical quantities such as temperature, pressure and refractive index have become common with nanophotonics and nanoplasmonics resonance cavities. As excellent transducers to convert small variations in the local refractive index into measurable spectral shifts, resonance cavities are being used extensively in a variety of disciplines ranging from bio-sensing and pressure gauges to atomic and molecular spectroscopy. Chip-scale microring and microdisk resonators (MRRs) are widely used for these purposes owing to their miniaturized size, relative ease of design and fabrication, high quality factor, and versatility in the optimization of their transfer function.The principle of operation of such resonative sensors is based on monitoring the spectrum dependence of the resonator subject to minute variation in its surrounding (e.g., different types of atoms and molecules, gases, pressure, temperature).  Yet despite several important accomplishments, such optical sensors are still limited in their performances, and their miniaturization is highly challenging.Now, a team from the Hebrew University of Jerusalem has demonstrated an on-chip sensor capable of detecting unprecedentedly small frequency changes. The approach consists of two cascaded microring resonators, with one serving as the sensing device and the other playing the role of a reference—thus eliminating environmental and system fluctuations such as temperature and laser frequency."Here we demonstrate a record-high sensing precision on a device with a small footprint that can be integrated with standard CMOS technology, paving the way for even more exciting measurements such as single particle detection and high precision chip scale thermometry," said Prof. Uriel Levy, Director of the Harvey M. Krueger Family Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem, and a faculty member at the Department of Applied Physics in the Rachel and Selim Benin School of Computer Science and Engineering.Among the innovations that made this development possible are chip scale integration of reference measurement, and a servo-loop locking scheme that translates the measured effects from the optical domain to the radio frequency domain. These enabled the researchers to quantify their system capabilities using well-established RF technologies, such as frequency counters, spectrum analyzers, and atomic standards.Reference:TCRT1000GP2S60ITR8307/L24/TR8  

Researchers from the Graphene Flagship, working at the AMBER centre in Trinity College Dublin, Ireland in collaboration with researchers from University of Siegen, Germany, and University of Vienna, Austria, have demonstrated ultrafast and highly sensitive gas sensors using platinum selenide (PtSe2). This material – a transition metal dichalcogenide (TMD) – has promising potential in different areas of nanoelectronics, including optoelectonics as well as sensing. This research, published in ACS Nano, demonstrates the potential of PtSe2 in a range of applications, and presents this little-studied material as an excellent candidate for further investigation.The new TMD was created using a metal conversion method, in which thin platinum film is converted into PtSe2 by thermally assisted conversion in selenium vapour at 400 °C. PtSe2 now joins the growing class of stable TMDs. Georg Duesberg, from Trinity College Dublin, is the principal investigator of the study. He said "We performed a screening study of materials, to check a few different material combinations. The conversion of metals is helpful in the quest for new materials, because it is simple to do. Of the other combinations that worked, many immediately oxidised, so they were not stable. We were very lucky to find a sweet spot with this material, and to be able to synthesise it on a large scale."One of the benefits of PtSe2 is the method of fabrication, which is compatible with silicon chip fabrication. "We grow PtSe2 at 400 °C which makes it potentially suitable for so-called back end of line (BEOL) processing. This means that it can be combined with existing device architectures to add new functionality," said Niall McEvoy, a researcher at Trinity College Dublin who performed the growth experiments. BEOL processing comes after the actual fabrication of integrated circuits of a silicon chip, It is crucial that the temperature is less than 450 °C, to preserve the functionality of the integrated circuit. "This is very interesting for the Flagship's push towards industrial applications," added Duesberg. "This potentially can be grown on top of a chip. You can imagine using this material for the Internet of Things, sensors and so on."To demonstrate possible applications for the new material, the researchers tested its performance in sensing NO2. "All of our homegrown materials are tested as gas sensors. PtSe2 showed excellent results, high sensitivity, excellent response time and nearly complete recovery," said Kangho Lee, a researcher at Trinity College Dublin who performed the gas sensing experiments. Gas molecules adsorbed onto the surface of the PtSe2 change its conductivity, lowering the resistance. The researchers found that the PtSe2 had extremely high sensitivity, measuring 100 ppb NO2 at room temperature. The sensor was also extremely fast to respond to the gas – detecting low quantities of gas in only seconds – and recovering completely within a minute when the inert atmosphere was restored.For commercial sensing applications, the sensor must be responsive only to specific gases, so that changes in environmental conditions can be monitored. McEvoy is optimistic that the PtSe2 can be treated to have the selective sensing properties needed. "With some added processing steps, to engender selectivity, PtSe2 could potentially be used in a wide array of industrial chemical sensing applications," he said. A potential route to selective sensing could be the addition of chemical groups that are responsive to the chosen gas.Reference:2790427929314100009 

Wearable sensors that monitor heart rate, activity, skin temperature, and other variables can reveal a lot about what is going on inside a person, including the onset of infection, inflammation, and even insulin resistance, according to a study by researchers at the Stanford University School of Medicine.An important component of the ongoing study is to establish a range of normal, or baseline, values for each person in the study and when they are ill. “We want to study people at an individual level,” said Michael Snyder, Ph.D., professor, and chair of genetics. Snyder is the senior author of the study, which was published online in PLOS Biology.  Altogether, the team collected nearly 2 billion measurements from 60 people, including continuous data from each participant’s wearable biosensor devices and periodic data from laboratory tests of their blood chemistry, gene expression, and other measures. Participants wore between one and seven commercially available activity monitors and other monitors that collected more than 250,000 measurements a day.  The team collected data on weight; heart rate; oxygen in the blood; skin temperature; activity, including sleep, steps, walking, biking, and running; calories expended; acceleration; and even exposure to gamma rays and X-rays. “I was very impressed with all the data that was collected,” said Eric Topol, MD, professor of genomics at the Scripps Research Institute, who was not involved in the study. “There’s a lot here — a lot of sensors and a lot of different data on each person.” The study demonstrated that, given a baseline range of values for each person, it is possible to monitor deviations from normal and associate those deviations with environmental conditions, illness, or other factors that affect health. Distinctive patterns of deviation from normal seem to correlate with particular health problems. Algorithms designed to pick up on these patterns of change could potentially contribute to clinical diagnostics and research. The work is an example of Stanford Medicine’s focus on precision health, whose goal is to anticipate and prevent disease in the healthy and to precisely diagnose and treat disease in the ill. On a long flight to Norway for a family vacation last year, Snyder noticed changes in his heart rate and blood oxygen levels. As one of the 60 participants in the digital health study, he was wearing seven biosensors.  From previous trips, Snyder knew that his oxygen levels normally dropped during airplane flights and that his heart rate increased at the beginning of a flight — as occurred in other participants. But the values typically returned to normal over the course of a long flight and after landing. This time, his numbers didn’t return to baseline. Something was up, and Snyder wasn’t completely surprised when he went on to develop a fever and other signs of illness.  The fact that you can pick up infections by monitoring before they happen is very provocative. Two weeks earlier, he’d been helping his brother build a fence in rural Massachusetts, so his biggest concern was that he might have been bitten by a tick and infected with Lyme disease. In Norway, Snyder persuaded a doctor to give him a prescription for doxycycline, an antibiotic known to combat Lyme disease. Subsequent tests confirmed that Snyder had indeed been infected with the Lyme microorganism. Snyder was impressed that the wearable biosensors picked up the infection before he even knew he was sick. “Wearables helped make the initial diagnosis,” he said.  Subsequent data analysis confirmed his suspicion that the deviations from normal heart rate and oxygen levels on the flight to Norway had indeed been quite abnormal. “The fact that you can pick up infections by monitoring before they happen is very provocative,” said Topol. For Snyder, the Lyme diagnosis is just the tip of the iceberg — part of very early work to begin querying massive data sets of health information. The results of the current study raise the possibility of identifying inflammatory disease in individuals who may not even know they are getting sick. For example, in several participants, higher-than-normal readings for heart rate and skin temperature correlated with increased levels of C reactive protein in blood tests. C reactive protein is an immune system marker for inflammation and often indicative of infection, autoimmune diseases, developing cardiovascular disease, or even cancer. Snyder’s own data revealed four separate bouts of illness and inflammation, including the Lyme disease infection and another that he was unaware of until he saw his sensor data and an increased level of C reactive protein. The wearable devices could also help distinguish participants with insulin resistance, a precursor for Type 2 diabetes. Of 20 participants who received glucose tests, 12 were insulin-resistant. The team designed and tested an algorithm combining participants’ daily steps, daytime heart rate, and the difference between daytime and nighttime heart rate. The algorithm was able to process the data from just these few simple measures to predict which individuals in the study were likely to be insulin-resistant. The study also revealed that declines in blood-oxygen levels during airplane flights were correlated with fatigue. Fortunately, the study showed that people tend to adapt on long flights; oxygen levels in their blood go back up, and they generally feel less fatigued as the hours go by. “The desaturation of oxygen in flight was not something I anticipated,” said Topol. “Whenever you walk up and down the aisle of a plane, everyone is sleeping, and I guess there may be another reason for that besides that they partied too hard the night before. That was really interesting, and I thought it was great that the authors did that.” Topol noted that one of the biosensors used in the study doesn’t work very well and that another has been recalled. “A few are not going to hold up,” he said. “Either they are not going to be available or they are going to be proven to not be very accurate." "But what is good about what the authors did here is that they weren’t just relying on one device. They did everything they could with the kind of sensors that are available today to get data that was meaningful.” During a visit to the doctor, patients normally have their blood pressure and body temperature measured, but such data is typically collected only every year or two and often ignored unless the results are outside of the normal range for entire populations. But biomedical researchers envisage a future in which human health is monitored continuously. “We have more sensors on our cars than we have on human beings,” said Snyder. In the future, he said, he expects the situation will be reversed and people will have more sensors than cars do. Already, consumers have purchased millions of wearable devices, including more than 50 million smartwatches and 20 million other fitness monitors. Most monitors are used to track activity, but they could easily be adjusted to more directly track health measures, Snyder said. We have more sensors on our cars than we have on human beings. With a precision health approach, every person could know his or her normal baseline for dozens of measures. Automatic data analysis could spot patterns of outlier data points and flag the onset of ill health, providing an opportunity for intervention, prevention, or cure. FAQ 1. What is wearable sensor?Wearable sensors, just as the name implies, are integrated into wearable objects or directly with the body in order to help monitor health and/or provide clinically relevant data for care. ... However, recent focus has shifted to wearable sensing platforms, exploiting stretchable and flexible electronics. 2. What can wearable sensors measure?The use of wearable sensors for sports is at its infancy, with the majority of devices currently used to measure movement-based parameters such as distance, velocity, and acceleration. 3. What are wearable sensors made of?At present, wearable temperature sensors also use a variety of nanomaterials, including conductive polymers,96, 97 graphene,89, 98 CNTs,46, 99 nickel,100 silver,101, 102 and copper metal nanoparticles and nanowires103 as thermal-sensing elements. 4. What are examples of wearable technology?Common examples of wearable technology include:Smart jewelry, such as rings, wristbands, watches and pins. ...Body-mounted sensors that monitor and transmit biological data for healthcare purposes.Fitness trackers, often in the form of wristbands or straps, that monitor things like physical activity and vital signs. 5. What are the wearable sensors used for?Wearable sensors are used to gather physiological and movement data thus enabling patient's status monitoring. Sensors are deployed according to the clinical application of interest. 6. What can wearable devices be used for?Wearables are electronic technology or devices incorporated into items that can be comfortably worn on a body. These wearable devices are used for tracking information on real time basis. They have motion sensors that take the snapshot of your day to day activity and sync them with mobile devices or laptop computers. 7. How we can monitor activity in wearable devices?Present wearable technologies include accelerometers, gyroscopes, sole sensors, and barometric pressure sensors mounted over the body. According to the purpose of the use, different body sensors have been developed with a capacity to monitor physiological and biochemical properties, posture and motion. 8. What is the value of the use of wearable microsensors?Using on-board sensors, wearable devices can provide critical information about athlete's performance and well-being. Athlete tracking is an important functionality of wearable devices that relies on positioning data which also influences the accuracy of numerous other attributes. 9. What health conditions require a wearable device?These devices will be especially important for improving the health and control of chronically ill patients and for those with conditions like asthma, COPD, diabetes, and cardiovascular disease. The focus of this paper revolves around wearable devices for asthma, but can be applied for any chronic condition. 10. What are the pros and cons of wearable technology?Pros and Cons of Wearable Tech:Pro: Wearable Tech is Convenient.Con: Wearable Tech is Limited.Pro: Most Wearable Tech is Discreet.Con: Some Wearable Tech is Not Discreet.Pro: Wearable Tech is Useful.Con: Wearable Tech is Expensive. Reference:EE-TP109IS471FSEIS489E