There Are Several Kinds of Pressure Sensors On The Market. What Are Their Principles?

With the development of the times, pressure gauges have been gradually eliminated. At present, more pressure transmitters are used to convert pressure into electrical signals.

The core of pressure sensor is the sensor inside, so today Jichuang Technology will introduce these pressure sensors.

1. Piezoelectric pressure sensors

Piezoelectric pressure sensor is mainly based on piezoelectric effect. It uses electrical components and other machinery to convert the measured pressure into electricity, and then carries out related measurement work, such as many pressure transmitters and pressure sensors. Piezoelectric sensors can not be used in static measurement, because the charge acted by external force can be preserved only when the circuit has infinite input resistance. But that's not the case. Therefore, piezoelectric sensors can only be used in dynamic measurement. Its main piezoelectric materials are dihydrogen phosphate, potassium sodium tartrate and quartz. Piezoelectric effect is found on quartz.

2. Piezoresistive pressure sensor

Piezoresistive effect is the main basis of piezoresistive pressure sensor. Piezoresistive effect is used to describe the resistance change of material under mechanical stress. Unlike the piezoelectric effect mentioned above, piezoresistive effect only produces impedance change, but does not generate charge. (This is one of the most widely used sensors at present.)

3. Capacitive pressure sensor

Capacitive pressure sensor is a kind of pressure sensor which uses capacitance as sensing element and converts the measured pressure into capacitance value change. This kind of pressure sensor usually uses circular metal film or plated metal film as an electrode of capacitor. When the film is sensitive to pressure and deformed, the capacitance formed between the film and the fixed electrode changes. Through the measuring circuit, the electric signal which has a certain relationship with the voltage can be output. Capacitive pressure sensor is a kind of capacitive sensor with variable polar distance. It can be divided into single capacitive pressure sensor and differential capacitive pressure sensor. (This is one of the most widely used sensors at present.)

4. Inductive pressure sensor

The working principle of inductance pressure sensor is due to the difference of magnetic material and permeability. When pressure acts on diaphragm, the size of air gap changes, and the change of air gap affects the change of coil inductance. The processing circuit can convert the change of inductance into corresponding signal output, so as to achieve the purpose of measuring pressure. The pressure sensor can be divided into two kinds according to the change of magnetic circuit: variable reluctance and variable permeability. Inductive pressure transducer has the advantages of high sensitivity and wide measurement range, but its disadvantage is that it can not be used in high frequency dynamic environment.

5. Hall pressure sensor

Hall pressure sensor is based on Hall effect of some semiconductor materials. Hall effect refers to the phenomenon that when a solid conductor is placed in a magnetic field and current passes through, the charge carriers in the conductor are biased to one side by Lorentz force, and then a voltage (Hall voltage) is generated. The electric field force induced by voltage will balance the Lorentz force. Through the polarity of Hall voltage, it can be confirmed that the current inside the conductor is caused by the motion of the negative charged particles (free electrons).

6. Vibrochord pressure sensor

Vibrating string pressure sensor belongs to frequency sensitive sensor. This kind of frequency measurement has the desired high accuracy, because time and frequency are physical parameters that can be accurately measured, and the influence of cable resistance, inductance, capacitance and other factors can be neglected in the transmission process of frequency signal. At the same time, the vibrating string pressure sensor also has strong anti-interference ability, small zero drift, good temperature characteristics, simple structure, high resolution, stable performance, easy data transmission, processing and storage, easy to achieve digital instrument, so the vibrating string pressure sensor can also be used as one of the development directions of sensing technology.

These six are basically all the pressure sensors on the market at present, among which piezoresistive and capacitive sensors are the most widely used.