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The principle and application of several common pressure sensors are introduced.

Pressure sensor is one of the most commonly used sensors in industrial practice, which is widely used in various industrial self-control environments, involving water conservancy and hydropower, railway traffic, intelligent building, production and control, aerospace, military, petrochemical, oil well, electric power, ship, machine tool, pipe and so on. Principle and application of common sensor

1, principle and application of strain gauge pressure sensor

There are many kinds of mechanical sensors, such as resistance strain gauge pressure sensor, semiconductor strain gauge pressure sensor, piezoresistive pressure sensor, inductance type pressure sensor, capacitive pressure sensor, resonant pressure sensor and capacitive accelerometer. But the most widely used type is piezoresistive pressure sensor. It has very low price, high accuracy and good linearity. Here we mainly introduce this kind of sensor.

When we extract the resistive force sensor, we first recognize the resistance strain gage. Resistance strain gage is a sensitive device that converts strain changes on the tested parts to an electrical signal. Pressure sensor is one of the main components of piezoresistive strain sensor. The most widely used resistance strain gauges are two kinds of metal strain gauges and semiconductor strain gauges. Metal resistance strain gauges also have two kinds of fillet strain gauges and foil foil strain gauges.

The strain sheet is usually glued to the mechanical strain matrix through a special adhesive and product. When the stress changes in the matrix, the resistance strain gauge also produces deformation, which changes the resistance of the strain sheet and changes the voltage added to the resistance. The strain generated in the strain is usually small, and the strain gauge is usually made up of a strain bridge, which is amplified by a subsequent instrument amplifier and retransmitted to the processing circuit (usually A/D conversion and CPU) display or actuator.

2, principle and application of ceramic pressure sensor

The corrosion resistant ceramic pressure sensor of the pressure sensor has no liquid transmission, and the pressure directly acts on the front surface of the ceramic diaphragm to make the diaphragm produce tiny deformation. The thick film resistance is printed on the back of the ceramic diaphragm and connected to a Wheastone bridge (closed bridge). The bridge is produced by the piezoresistor effect of the piezoresistor. A voltage signal with a high linearity and proportional to the excitation voltage is proportional to the pressure. The standard signals are calibrated to 2 / 3 / 3.3 mV/V according to the pressure range, which can be compatible with the strain sensor. By laser calibration, the sensor has high temperature stability and time stability. The temperature compensation of the sensor is 0~70 degrees C, and it can be directly contact with most of the medium.

Ceramics are recognized as high elasticity, corrosion resistance, wear resistance, impact and vibration materials. The thermal stability of ceramic and its thick film resistance can make its working temperature range up to -40 ~ 135 C, and it has high accuracy and high stability in measurement. The degree of electrical insulation is 2kV, the output signal is strong, the long-term stability is good, the ceramic sensor with high characteristic and low price will be the development direction of the pressure sensor. In the European and American countries, there is a trend to replace the other types of sensors in the European and American countries. In China, more and more users use ceramic sensors to replace the diffusion silicon pressure sensors.

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