Sick Sensors – An Introduction to Seven Common Sensors

1. Physical sensor:

A physical sensor is a sensor that detects a physical quantity. It is a device that uses certain physical effects to convert the measured physical quantity into a signal in the form of energy that can be easily processed. There is a definite relationship between the output signal and the input signal. The main physical sensors are photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, thermoelectric sensors, optical fiber sensors, etc. As an example, let's look at the more commonly used photoelectric sensors. This type of sensor converts the optical signal into an electrical signal, it directly detects the radiation information from the object, and can also convert other physical quantities into optical signals.

The main principle is the photoelectric effect: when light hits a substance, the electrical effects on the substance change, including electron emission, conductivity and potential current. Obviously, devices that can easily produce such effects 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 irradiation, convert the light energy into electrical energy through a device such as a photoresistor, and then obtain the required output electrical signal through amplification and noise removal processing. Here the output electrical signal has a certain relationship with the original optical signal, usually close to linear, so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be compared to photoelectric sensors.

2. Photoelectric sensor:

A photoelectric sensor is a sensor that uses a photoelectric element as a detection element. It first converts the measured change into a change in the optical signal, and then further converts the optical signal into an electrical signal with the help of an optoelectronic component. Photoelectric sensors are generally composed of three parts: light source, optical path and optoelectronic components.

Photoelectric sensors are generally composed of two parts: a processing path and a processing element. The basic principle is based on the photoelectric effect, which converts the measured change into a change in the optical signal, and then further converts the non-electrical signal into an electrical signal with the help of an optoelectronic component. The photoelectric effect refers to the irradiation of an object with light, which can be regarded as a series of photons with a certain energy to bombard the object, at this time, the photon energy is transferred to the electron, and the whole energy of a photon is absorbed by an electron at one time, and the electron will change its state after obtaining the energy transmitted by the photon, so that the object irradiated by the light will produce the corresponding electrical effect.

Photoelectric sensor is a sensor with optoelectronic device as the conversion element, which can be used to detect non-electrophysical quantities that directly cause changes in the amount of light, such as light intensity, illuminance, radiation temperature measurement, gas composition analysis, etc.; It can also be used to detect other non-electric amounts that can be converted into changes in the amount of light, such as part diameter, surface roughness, strain, displacement, vibration, velocity, acceleration, and the identification of the shape and working state of the object. Photoelectric sensors are non-contact, fast responding, and reliable, so they are widely used in industrial automation devices and robots. The continuous emergence of new optoelectronic devices, especially the birth of CCD image sensors, has opened a new page for the further application of photoelectric sensors.

3. Bionic sensor:

Biomimetic sensor is a new type of sensor using a new detection principle, which uses immobilized cells, enzymes or other bioactive substances to cooperate with a transducer to form a sensor. This sensor is a new type of information technology developed by the mutual penetration of biomedicine, electronics and engineering in recent years. This sensor is characterized by its high functionality and long service life. Among the biomimetic sensors, bioanalog sensors are more commonly used.

Bionic sensors can be divided into enzyme sensors, microbial sensors, organelle sensors, tissue sensors, etc. according to the medium used. In the figure, we can see that biomimetic sensors are closely related to all aspects of biological theory, and are the direct result of the development of biological theory. Among the sensors for biological simulation, the urea sensor is the most recently developed sensor.

At present, although many bionic sensors have been successfully developed, the stability, reproducibility and mass production of bionic sensors are obviously insufficient, so the bionic sensing technology is still in its infancy, therefore, in addition to continuing to develop a new series of bionic sensors and improving the existing series, the immobilization technology of bioactive film and the solidification of bionic sensors are worthy of further research.

4. Water quality PH sensor:

A WATER QUALITY PH SENSOR IS USUALLY COMPOSED OF A CHEMICAL PART AND A SIGNAL TRANSMISSION PART. A sensor that detects the concentration of hydrogen ions in the analyte and converts it into a corresponding usable output signal. pH sensors can be used to determine the pH value in large reactors or process lines; High temperature sterilization, CIP cleaning; Electrode lengths are available in 120, 150, 220, 250, 450 mm, and more. United States sensorex water quality PH sensor - S290C is used for pH measurement in a variety of occasions, such as: pH measurement in wastewater and sewage applications, pH measurement in electroplating wastewater applications, pH measurement in high temperature applications, pH measurement in fermentation occasions, pH measurement in high pressure occasions and other occasions for pH measurement.

5. Electromagnetic sensor:

Magnetic sensors are the oldest sensors, and the compass is one of the earliest applications of magnetic sensors. However, as a modern sensor, in order to facilitate signal processing, a magnetic sensor is required to convert the magnetic signal into an electrical signal output. The earliest application was a magnetoelectric sensor based on 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 new magnetic sensors based on high-performance magnetic sensing materials.

Among the electromagnetic sensors used today, the magnetic rotation sensor is one of the most important. The magnetic rotation sensor is mainly composed of several parts, such as semiconductor magnetoresistive elements, permanent magnets, retainers, and housings. The typical structure is to install a pair of magnetoresistive elements on the stimulation of a permanent magnet, the input and output terminals of the components are connected to the retainer, and then installed in a metal box, and then sealed with engineering plastics to form a closed structure, which has good reliability. Magnetic rotation sensors have many advantages that semiconductor magnetoresistive elements cannot match the form factor of an electromagnetic sensor. In addition to having a high sensitivity and a large output signal, it also has a strong speed detection range, which is the result of the development of electronic technology. In addition, the sensors can be used in a wide temperature range, have a long operating life, are highly resistant to dust, water and oil, and are therefore resistant to a wide range of environmental conditions and external noise. Therefore, this kind of sensor is widely valued in industrial applications.

Magnetic rotation sensors have a wide range of applications in factory automation systems because they have satisfactory characteristics and are maintenance-free. It is mainly used in the rotation detection of machine tool servo motors, the positioning of robot arms in factory automation, the detection of hydraulic strokes, the position detection of factory automation related equipment, the detection unit of rotary encoders and various rotating detection units. Modern magnetic rotation sensors mainly include four-phase sensors and single-phase sensors. In the working process, the four phase difference rotation sensors use one pair of detection units to realize differential detection, and the other pair to realize inverted differential detection. In this way, the detection power of a four-phase sensor is four times greater than that of a single element. The two-element single-phase rotary sensor also has its own advantages, that is, it is small and reliable, and the output signal is large, it can detect low-speed movement, and it has strong anti-environmental and anti-noise capabilities, and has low cost. Therefore, there will also be a good market for single-phase sensors.

6. Magneto-optical effect sensor:

Modern electrical measurement technology is becoming more and more mature, and has been widely used in the measurement of electrical and non-electrical quantities due to its advantages of high precision, convenient microcomputer connection to achieve automatic real-time processing, etc. However, the electrical measurement method is easy to be interfered with, and in AC measurement, the frequency response is not wide enough and there are certain requirements for withstand voltage and insulation, which can be solved in today's rapid development of laser technology.

Magneto-optical sensors are high-performance sensors developed using laser technology. Laser is another new technology that developed rapidly in the early sixties of this century, and its emergence marks that people have entered a new stage in mastering and using light waves. Due to the low monochromaticity of ordinary light sources in the past, many important applications were limited, and the emergence of lasers has made radio technology and optical technology advance by leaps and bounds, penetrate and complement each other. Now, many sensors have been made by using lasers, and many technical problems that could not be solved before have been solved, making it suitable for dangerous and flammable places such as coal mines, oil and gas storage.

For example, optical fiber sensors made of lasers can measure the parameters of crude oil injection and oil tank cracking. At the test site, power supply is not required, which is particularly useful for petrochemical plants with strict safety and explosion protection measures, and can also be used to implement telemetry chemistry with optical methods in certain parts of large steel plants.

In the use of magneto-optical effect sensors, the most important thing is to choose magneto-optical medium and laser, different devices have different capabilities in terms of sensitivity and working range. With the emergence of high-performance lasers and new magneto-optical media in recent decades, the performance of magneto-optical sensors is getting stronger and stronger, and the application is becoming more and more extensive. As a special-purpose sensor, magneto-optical effect sensor can play its own function in a specific environment, and it is also a very important industrial sensor.

7. Pressure sensor:

Pressure sensors are one of the most commonly used sensors in industrial practice, and the pressure sensors we usually use are mainly made using the piezoelectric effect, which is also called piezoelectric sensors.

We know that crystals are anisotropic, and amorphous are isotropic. Some crystalline media are deformed by mechanical force in a certain direction, resulting in a polarization effect; When the mechanical force is removed, it will return to an uncharged state, that is, when under pressure, some crystals may produce an electric effect, which is called the polarization effect. It is based on this effect that scientists developed pressure sensors.

The piezoelectric effect is the main operating principle of piezoelectric sensors, which cannot be used for static measurements because the charge after the action of an external force is only saved if the loop has an infinite input impedance. This is not the case, so this dictates that piezoelectric sensors can only measure dynamic stresses.

Piezoelectric sensors are mainly used in the measurement of acceleration, pressure, and force. Piezoelectric accelerometers are a commonly used type of accelerometer. It has the excellent characteristics of simple structure, small size, light weight and long service life. Piezoelectric accelerometers have been widely used in vibration and shock measurement of aircraft, automobiles, ships, bridges and buildings, especially piezoelectric sensors have a special position in the aviation and aerospace fields. It can also be used to measure the combustion pressure inside the engine and the vacuum level. It can also be used in the military industry, for example, to measure the change in chamber pressure and the blast wave pressure at the moment when a gun bullet is fired in the chamber.

It can be used to measure both large and small pressures. Piezoelectric sensors are also widely used in biomedical measurements, for example, ventricular catheter microphones are made of piezoelectric sensors, because measuring dynamic pressure is so common, so piezoelectric sensors are very widely used. In addition to piezoelectric sensors, there are piezoresistive sensors that use the piezoresistive effect and strain gauge sensors that use the strain effect, and these different pressure sensors can play their unique role in different situations by using different effects and different materials.

Sick Sensors – An Introduction to Seven Common Sensors

Sick Sensors – An Introduction to Seven Common Sensors

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