What are the types of pressure sensor？

What is Pressure sensor？

A pressure sensor can feel the pressure signal, and by a certain law will be converted to the pressure signal available output of the electrical signal device or device.  

   
Pressure sensors are usually composed of pressure-sensitive components and signal-processing units. According to different types of test pressure, pressure sensors can be divided into gauge pressure sensors, absolute pressure sensors, and differential pressure sensors.  

     
Pressure sensors are the most commonly used in industrial practice of a sensor, which is widely used in a variety of industrial automation environments, involving water conservancy and hydropower, railroad transportation, intelligent buildings, production automation, aerospace, military, petrochemical, oil wells, electric power, ships, machine tools, pipelines, and many other industries.

Common Units of Pressure

Europe the United States and other countries are accustomed to using psi as the unit PSI English full name Pounds per square inch, is “pound-force / square inch”.

1bar≈14.5psi1psi=6.894757kPa=0.0689476barIn China, we generally describe the pressure of the gas with “kilograms” (rather than “pounds”), the unit is In China, we generally describe the pressure of a gas as “kg” (instead of “jin”), and the unit is “kgf/cm2”, which means “kilogram-force per square centimeter”. In addition, there are Pa (Pascal, a Newton acting on a square meter), kPa, MPa, bar, millimeters of water, millimeters of mercury, and other units of pressure.

Five types of pressure sensors

◆Strain Gauge Pressure Sensor-High Precision Most Widely Used   

    The core of the resistance strain gauge pressure sensor is a resistance strain gauge, which is a metal sheet that deforms when it is subjected to a force. When the strain gauge is subjected to an external force, its length and cross-sectional area change, which in turn changes the resistance value.        

Strain sensors can measure physical quantities such as strain stress, bending moment, torque, acceleration, displacement, etc. and are most widely used in different fields. They are especially used in industrial weighing system products that require high accuracy, such as platform scales and hopper weighing systems.

◆Ceramic Pressure Sensor-Resistant to Wear and Stability        

Ceramic is the ideal material for pressure sensors because of its elasticity, impact resistance, abrasion resistance, and stable performance. Ceramic pressure sensors do not have liquid transfer, but use ceramic directly as the sensing diaphragm, so that the pressure indirectly on the back of the ceramic diaphragm of the thick film resistance, connected to a Wheatstone bridge, resistance resistance changes through the bridge to produce a voltage signal proportional to the pressure, the excitation voltage.　　

Compared with metal strain gauges, ceramic pressure sensors, ' biggest feature is corrosion resistance, in the measurement of corrosive media pressure, such as in the chemical industry, refrigeration and other fields are often very useful. Secondly, ceramic pressure sensors are often composed of a layered structure, so they have a better resistance to pressure peaks, but the corresponding sensitivity may not be as good as the former performance.

◆Diffuse Silicon Pressure Sensors - Small Size, Big Signal        

The principle is that the pressure of the measured medium acts directly on the diaphragm of the sensor, causing the diaphragm to produce a micro-displacement proportional to the medium pressure, so that the sensor's resistance changes, and rely on the electronic circuit to detect the changes, and quickly convert and output the corresponding standard measurement signal.        

A significant advantage of diffusion silicon pressure sensors is a large signal output, for the back-end variable transmission conditioning line provides a great advantage, coupled with high resolution, high sensitivity, and its optional back-end circuit. Secondly, the compact size of diffusive silicon facilitates installation and can be widely used in medical devices to assist in biomonitoring.

◆Sapphire Pressure Sensor - Accurate and Highly Priced        

Similar to the first strain-resistor type, the receiving diaphragm deforms after being subjected to transmitted pressure, and after the change is sensed by the silicon-sapphire sensitive element, the bridge outputs an electrical signal that is proportional to the change in pressure.        

As a semiconductor-sensitive element, sapphire's metrological properties are unrivaled, not only will not occur hysteresis, fatigue, and creep phenomena, but also under very high hardness is not afraid of deformation. In addition, sapphire has very good elasticity and insulating properties, such sensors can work in a variety of extreme environments with high reliability, good accuracy, and very small temperature errors.

Its shortcomings are also very obvious - the price will be more than double compared to other pressure sensors, and the application scene is generally in the high-end or heavy equipment.

◆Piezoelectric Pressure Sensor - Dynamic Scene Advantages        

Piezoelectric pressure sensors work based on the piezoelectric effect. From the structural point of view, there is a thin cylinder inside, and when the inner side of the thin cylinder is subjected to pressure, the inner tension of the cylinder increases, which leads to an increase in its intrinsic vibration frequency. As long as the intrinsic vibration frequency of the vibration cylinder can be measured, you can know the size of the pressure.       

Piezoelectric sensors have excellent features such as simple structure, small size, lightweight and long service life. However, they cannot be used in static measurements, because the charge after being acted upon by an external force can be preserved only when there is an infinite input resistance in the loop, and therefore they are only used in dynamic measurements, such as piezoelectric inkjet printheads, and cameras that use piezoelectric MEMS for autofocusing, and so on.     

You can choose the appropriate model based on the type of pressure you are measuring and the environmental conditions. Each type of pressure sensor is suitable for specific applications, accuracy requirements, pressure range to be measured, and expected applications. If there are any selection issues, If you have any doubts or questions, please contact the Firstrate team immediately, we will provide you with 24-hour service and assistance.