What are the commonly used types of pressure sensors?

Pressure sensor is a commonly used detection instrument, which is generally composed of process connection elements, measurement circuits and differential pressure element sensors, and is widely used in industry, metallurgy, electric power, petroleum, chemical and other fields. Today, I will mainly introduce several commonly used types of pressure sensor products, I hope it can help you.

Ceramic pressure sensor ·

This sensor is corrosion-resistant, it is not transmitted by liquid, and the pressure is directly applied on the front surface of the sensor's ceramic diaphragm, at this time, the ceramic diaphragm will form a very small deformation, and the thick film resistance is printed on the back of the diaphragm, so that it can be connected to a Wheatstone bridge. According to the piezoresistive effect of the varistor, the bridge can be formed into a highly linear voltage signal, which is proportional to the excitation voltage of the flameproof temperature transmitter and proportional to the pressure. The standard signal is calibrated according to the pressure range and is compatible with strain gauge sensors.

According to laser calibration, the sensor has high temporal and temperature stability, its built-in temperature compensation range is 0 to 70, and it is also able to come into direct contact with many media.

Sapphire pressure sensor

It works according to the principle of strain resistance, and its metrological characteristics are very good, because the silicon-sapphire combination is used as a semiconductor sensitive element. Sapphire has good insulating properties and elasticity; Moreover, sapphire is very hard and stronger than silicon, so users do not need to fear it from deforming; The sapphire system is composed of a single crystal insulator element, so it does not suffer from creep, fatigue and hysteresis. Therefore, if the silicon-sapphire combination is used as a semiconductor sensitive element, the influence of temperature on its measurement becomes very small, and its working characteristics can still be maintained well even in a very high temperature environment, and sapphire also has a strong radiation resistance.

The use of this sensitive component greatly ensures product yield, improves measurement repeatability, and simplifies the manufacturing process. Transmitters and pressure sensors that use silicon-sapphire as semiconductor sensitive components can work normally in no matter how harsh the environment, and it has high cost performance, low temperature error, good accuracy and high reliability.

Strain gauge pressure sensor

There are many types of this kind of sensor, capacitive, resonant, inductive, resistance strain gauge and piezoresistive type, etc., but the piezoresistive type is the most widely used, it has a relatively good linearity, relatively high accuracy and relatively low **.

Diffusion silicon pressure sensor

When the pressure of the medium to be measured acts on the sensor diaphragm, the diaphragm will form a certain micro-displacement, which is proportional to the pressure of the medium, at this time, it will cause a certain change in the resistance value of the sensor, and the electronic circuit is used to detect this change, and then a standard measurement signal can be converted and output, which is corresponding to this pressure.

A pressure transducer is a device or device that can sense the pressure signal and convert the pressure signal into a usable output electrical signal according to a certain law. A pressure sensor usually consists of a pressure-sensitive element and a signal processing unit. According to different types of test pressure, pressure sensors can be divided into gauge pressure sensors, differential pressure sensors and absolute pressure sensors.

According to the different structures and principles, they can be divided into: strain gauge, piezoresistive, capacitive, piezoelectric, vibrating pressure sensors, etc. In addition, there are photoelectric, fiber-optic, ultrasonic pressure sensors, etc.

1. Strain gauge pressure sensor.

A strain gauge pressure sensor is a type of sensor that measures pressure indirectly by measuring the strain of various elastic elements. Depending on the material from which they are made, strain gauges can be divided into two categories: metals and semiconductors. The principle of operation of a strain gauge element is based on the "strain effect" of conductors and semiconductors, i.e. when the conductor and semiconductor material are mechanically deformed, their resistance values change.

2. Piezoresistive pressure sensor.

Piezoresistive pressure sensors are sensors made using the piezoresistive effect of monocrystalline silicon materials and integrated circuit technology. When the resistivity of a monocrystalline silicon material changes after being subjected to a force, an electrical signal output proportional to the change in force can be obtained through the measurement circuit. It is also known as a diffusion silicon piezoresistive pressure sensor, which is different from the adhesive strain gauge, which needs to feel the external force indirectly through the elastic sensitive element, but directly through the silicon diaphragm to feel the measured pressure.

3. Capacitive pressure sensor.

A capacitive pressure sensor is a pressure sensor that uses capacitance as a sensitive element to convert the measured pressure into a change in capacitance value. This kind of pressure sensor generally uses a round metal film or a metalized film as an electrode of the capacitor, and when the film is deformed by the pressure, the capacitance formed between the film and the fixed electrode changes, and the electrical signal with a certain relationship with the voltage can be output through the measurement circuit. Capacitive pressure sensors belong to the capacitive sensors with pole distance variation, which can be divided into single capacitive pressure sensors and differential capacitive pressure sensors.

4. Piezoelectric pressure sensor.

Piezoelectric pressure sensors are mainly based on the piezoelectric effect, which uses electrical components and other machinery to convert the pressure to be measured into electricity, and then carry out related measurement work with precision instruments, such as many pressure transmitters and pressure sensors.

Pressure sensors can be divided into a variety of types, and are widely used in a variety of media and objects to obtain pressure values. From the perspective of its working principle, there are many classifications of pressure sensors.

1. Piezoresistive pressure sensor

Resistive strain gauges are one of the main components of piezoresistive strain transducers. The working principle of metal resistance strain gauge, the phenomenon that the strain resistance adsorbed on the base material changes violently with the mechanical deformation, commonly known as the resistance strain effect.

2. Ceramic pressure sensor

The ceramic pressure sensor is based on the piezoresistive effect, the pressure acts directly on the front surface of the ceramic diaphragm, so that the diaphragm produces a slight deformation, the thick film resistance is printed on the back of the ceramic diaphragm, connected into a Wheatstone bridge, due to the piezoresistive effect of the varistor, the bridge produces a highly linear voltage signal proportional to the pressure, and the excitation voltage is also proportional, the standard signal is calibrated according to the different pressure ranges, etc., which can be compatible with the strain gauge sensor.

3. Diffusion silicon pressure sensor

The working principle of the diffusion silicon pressure sensor is also based on the piezoresistive effect, using the principle of piezoresistive effect, the pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic), so that the diaphragm produces a micro-displacement proportional to the pressure of the medium, so that the resistance value of the sensor changes, the electronic circuit is used to detect this change, and converts and outputs a standard measurement signal corresponding to the rapid pressure.

4. Piezoelectric pressure sensor.

The piezoelectric effect is the main operating principle of piezoelectric sensors, which cannot be used for static measurements because the charge after being acted upon by 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.

Strain gauge pressure sensors are sensors that measure pressure primarily by measuring the strain of an elastic element. Depending on the material, strain gauges are divided into metals and semiconductors. When a conductor is mechanically deformed from a semiconductor material, its resistance value changes.

Piezoresistive pressure sensors are sensors made of the piezoresistive effect of monocrystalline silicon materials and integrated circuits. When the resistivity of a monocrystalline silicon material changes when it is subjected to a force, an electrical signal proportional to the change in force is output through the measurement circuit. Unlike adhesive strain gauges, the measured pressure is mainly felt through the base grinding of the silicon diaphragm.

Capacitive pressure sensors mainly use capacitance, and the measured pressure is converted into a pressure sensor with a change in capacitance value. The electrode of the capacitor is a round metal film or a metallized film, and when the film is deformed by the pressure of the fight, the capacitance changes and an electrical signal is formed.

Piezoelectric pressure sensors are instruments that use the piezoelectric effect to reduce the amount of electricity from a pressure conversion stool with electrical components and other machinery, and then perform related measurement work.

There are many types of pressure sensors, and there are two commonly used types: piezoresistive pressure sensors and piezoelectric pressure sensors.

The working principle of piezoresistive pressure sensor is that when the varistor is pressurized, the resistance becomes higher and the pressure is repented, and the pressure can be detected by amplification by the amplifier and standard pressure calibration. The performance of a piezoresistive pressure sensor depends primarily on the varistor element (i.e., varistor), the amplification circuitry, and the calibration and aging processes in production.

Piezoresistive sensors use integrated circuit process technology to fabricate four equivalent thin-film resistors on a silicon wafer and form a bridge circuit. When not subjected to force, the bridge is in equilibrium and has no voltage output; When a force is applied, the bridge loses its balance and outputs a voltage proportional to the stress. Piezoresistive sensors work on the same principle as conventional semiconductor strain gauge sensors, which are based on the piezoresistive effect of semiconductor materials.

The piezoelectric pressure sensor principle is based on the piezoelectric effect. The piezoelectric effect is when some dielectrics are deformed by an external force in a certain direction, and their internal polarization will occur, and positive and negative opposite charges will appear on its two opposite surfaces at the same time. When the external force is removed, it will return to a state of non-positive charge, a phenomenon called positive piezoelectric effect.

When the direction of the force changes, the polarity of the charge also changes. Conversely, when an electric field is applied in the polarization direction of a dielectric, these dielectrics are also deformed, and when the electric field is removed, the deformation of the dielectric disappears, a phenomenon known as the inverse piezoelectric effect. There are many types and models of piezoelectric pressure sensors, which can be divided into diaphragm type and piston type according to the form of elastic sensing element and force mechanism reconstruction.

The diaphragm type is mainly composed of a body, a diaphragm and a piezoelectric element. The piezoelectric element is supported on the body, and the measured pressure is transmitted to the piezoelectric element by the diaphragm, and then the piezoelectric element outputs an electrical signal with a certain relationship with the measured pressure.

This sensor is characterized by its small size, good dynamic characteristics, high temperature resistance, etc. Modern measurement technology places increasing demands on the performance of sensors. Piezoelectric materials are best suited for the development of such pressure sensors.

Quartz is a very good piezoelectric material, and the piezoelectric effect is found on it. At present, the more effective method is to choose a quartz crystal cutting method suitable for high temperature conditions.

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