Common Pressure Sensor Technology Types
The pressure sensor is generally used to measure the pressure of the gas or liquid atmosphere where the sensor sensitive device is located, and is generally used to feed back to the main control unit of the system to achieve precise control of the system.As a major category of sensors, pressure sensors are widely used in different industries such as automobiles, industries, home appliances, and consumer electronics.Commonly used pressure sensors are distinguished from the sensing principle, which mainly include the following categories:
- Silicon piezoresistive technology
- Ceramic Resistor Technology
- Glass micro-melting technology
- Ceramic capacitor technology
The silicon piezoresistive technology is realized by the piezoresistive characteristics of semiconductors, and the piezoresistive characteristics of semiconductor materials depend on factors such as material type, doping concentration and crystal orientation.The technology can be realized by semiconductor technology, and has the advantages of small size, high yield, low cost, and high signal output sensitivity.The shortcomings are mainly reflected in the low degree of medium tolerance, poor temperature characteristics and poor long-term stability.Common in the range of medium and low pressure ranges, such as 5kPa~700kPa.There are also solutions in the industry to improve the dielectric tolerance of silicon piezoresistive technology through special packaging processes, such as oil filling, back pressure and other technologies, but it will also bring about problems such as a significant increase in cost.
The ceramic resistor technology uses the thick film printing process to print the Wheatstone bridge on the surface of the ceramic structure, and uses the varistor effect to convert the pressure signal of the medium into a voltage signal.Ceramic resistance technology has the advantages of moderate cost and simple process. At present, many domestic manufacturers provide ceramic resistance pressure sensor cores.However, the signal output sensitivity of this technology is low, the range is generally limited to 500kPa~10MPa, and the conventional hollow structure only relies on the diaphragm to bear the pressure, and the anti-overload capability is poor. When the pressure of the medium to be measured is overloaded, the ceramic resistance sensor will have diaphragm rupture. Risk of media leakage.
Glass micro-melting technology uses a high-temperature sintering process that combines silicon strain gauges with stainless steel structures.The equivalent four resistances of the silicon strain gauge form a Wheatstone bridge. When there is medium pressure on the other side of the stainless steel diaphragm, the stainless steel diaphragm produces a small deformation and causes the bridge to change, forming a voltage signal proportional to the pressure change.The glass micro-melting process is difficult to realize and the cost is high. The main advantage is that it has good medium tolerance and strong overload resistance. It is generally suitable for high pressure and ultra-high pressure ranges, such as 10MPa~200MPa, and the application is relatively limited.
The ceramic capacitor technology adopts a fixed ceramic base and a movable ceramic diaphragm structure, and the movable diaphragm is sealed and fixed to the base by means of glass paste or the like.
The electrode pattern is printed on the inner side of the two to form a variable capacitor. When the medium pressure on the diaphragm changes, the capacitance between the two changes accordingly. The signal is converted and conditioned by the conditioning chip and then output. Use for the rear stage.Ceramic capacitor technology has the advantages of moderate cost, wide range, good temperature characteristics, consistency, and long-term stability.