Sensor (detection device)

Sensor (detection device)

    Sensor (English Name: transducer / sensor) is a kind of detection device, which can feel the measured information and transform the information into electrical signal or other required information output according to certain rules, so as to meet the requirements of information transmission, processing, storage, display, recording and control.
 

    The characteristics of sensors include: miniaturization, digitization, intellectualization, multi-function, systematization and networking. It is the first step to realize automatic detection and control. With the existence and development of sensors, objects have sense of touch, taste, smell and other senses, which make them come to life gradually. According to their basic sensing functions, they are usually divided into ten categories: thermal sensor, photosensitive sensor, gas sensor, force sensor, magnetic sensor, humidity sensor, sound sensor, radiation sensor, color sensor and taste sensor.

Main role
 

    In order to obtain information from the outside world, people have to rely on sensory organs.

 

     However, it is not enough to rely on people's own sense organs in the study of natural phenomena, laws and production activities. In order to adapt to this situation, sensors are needed. Therefore, it can be said that the sensor is the extension of human facial features, also known as electrical facial features.
  

    With the advent of new technological revolution, the world has entered the information age. In the process of using information, the first thing to solve is to obtain accurate and reliable information, and the sensor is the main way and means to obtain information in the field of nature and production.
 

    In modern industrial production, especially in the process of automatic production, various sensors should be used to monitor and control various parameters in the production process, so as to make the equipment work in a normal state and make the products reach a better quality. Therefore, it can be said that without many excellent sensors, modern production will lose its foundation.
 

    Sensors play an important role in the research of basic subjects. With the development of modern science and technology, it has entered many new fields: for example, to observe the vast universe thousands of light-years on the macro level, to observe the particle world as small as FM on the micro level, to observe the evolution of celestial bodies as long as hundreds of thousands of years on the vertical level, and to observe the instantaneous reaction as short as S. In addition, a variety of technological researches, such as high temperature, low temperature, high pressure, high vacuum, strong magnetic field, weak magnetic field and so on, have also appeared, which play an important role in deepening the understanding of materials, developing new energy and new materials. Obviously, it is impossible to obtain a large amount of information that cannot be directly obtained by human senses without appropriate sensors. The first obstacle of many basic scientific research lies in the difficulty of obtaining object information, and the emergence of some new mechanisms and high-sensitivity detection sensors will often lead to breakthroughs in this field. The development of some sensors is often the pioneer of some frontier disciplines.
 

    Sensors have already penetrated into a wide range of fields, such as industrial production, space development, ocean exploration, environmental protection, resource investigation, medical diagnosis, bioengineering, and even cultural relics protection. It is no exaggeration to say that almost every modern project, from the vast space to the vast ocean to all kinds of complex engineering systems, cannot do without all kinds of sensors.

 

Thus, the important role of sensor technology in the development of economy and social progress is very obvious. All countries in the world attach great importance to the development of this field. It is believed that in the near future, sensor technology will make a leap and reach a new level commensurate with its important position.

weigh
 

    Load cell is a force to electricity conversion device which can convert gravity into electrical signal, and it is a key component of electronic weighing instrument.

 

There are many kinds of sensors that can realize force to electricity conversion, such as resistance strain type, electromagnetic force type and capacitance type. The electromagnetic force type is mainly used for electronic balance, and the capacitive type is used for some electronic hanging scales, while the vast majority of weighing products use resistance strain type weighing sensors. The resistance strain type load cell has the advantages of simple structure, high accuracy, wide application, and can be used in relatively poor environment. Therefore, the resistance strain type load cell has been widely used in weighing instrument.

 

Resistance strain gauge
 

    The resistance strain gauge in the sensor has the strain effect of metal, that is, mechanical deformation is produced under the action of external force, so that the resistance value changes accordingly. The resistance strain gauge mainly includes metal and semiconductor. The metal strain gauge can be divided into wire type, foil type and film type. Semiconductor strain gauge has the characteristics of high sensitivity (usually dozens of times of wire type and foil type) and small transverse effect.
 

Piezoresistive
 

    Piezoresistive sensor is based on the piezoresistive effect of semiconductor materials through the diffusion resistance on the substrate of semiconductor materials. The substrate can be directly used as a sensing element, and the diffusion resistance is connected into a bridge in the substrate. When the substrate is deformed by external force, the resistance values will change, and the bridge will produce the corresponding unbalanced output.

 

The substrate (or diaphragm) used as piezoresistive sensor is mainly made of silicon and germanium. Silicon piezoresistive sensor made of silicon as sensitive material has been paid more and more attention, especially the solid-state piezoresistive sensor used to measure pressure and velocity.