Widely use of pressure sensor:
Now,the pressure sensor is a typical automotive sensor, it is widely used in the car. The history of automotive pressure sensors began in 1979,a variety of absolute pressure sensors for engine combustion control. Subsequently, it is widely used in high pressure applications such as suspension pressure detection and air conditioning refrigeration pressure detection.The pressure sensor is also extended to low pressure applications,such as volatile gasoline leak detection. Now, the pressure sensor is further extended to high pressure applications such as gasoline combustion and diesel common rail combustion injection systems. Obviously,the pressure sensor in the car has broad prospects for development.
The pressure sensitive element of the piezoresistive pressure sensor is a piezoresistive element that operates based on the piezoresistive effect.The so-called piezoresistive element actually refers to the diffusion resistance of an integrated circuit process on a substrate of a semiconductor material, and when it is subjected to external force, its resistance changes due to the change in resistivity. Diffusion resistance to work properly to be attached to the elastic components, commonly used is a single crystal silicon diaphragm.
The piezoresistive chip is housed in a housing with a fixed silicon cup structure. On a circular monocrystalline silicon diaphragm, four diffusion resistors are arranged,two in the compressive stress region, and the other two in the tensile stress region, which form a full bridge measurement circuit. The silicon diaphragm is fixed with a circular silicon cup with two pressure chambers on both sides, a high pressure chamber connected to the measured pressure, and the other being a low pressure chamber,which is connected to the pressure and is normally in contact with the atmosphere. When there is pressure, the diaphragm deformation, so that the resistance of the two pairs of resistance changes, the bridge out of balance, the output voltage reflects the pressure on both sides of the diaphragm to bear the size of the difference.
In order to transform the pressure signal into an electrical signal,the Wheatstone detection bridge is fabricated on the monocrystalline silicon wafer using the strain principle, making the monocrystalline silicon wafer a sensitive element that integrates stress sensitivity and power conversion.
A single silicon chip can only be part of a detection unit can not independently complete the signal conversion, it must have a specific package to have the ability to detect pressure.
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