Piezoresistive pressure sensor working principle
The piezoresistive pressure sensor works by using ISO technology to package the sensitive chip of the semiconductor material in the housing of the stainless steel corrugated diaphragm, and fill the silicone oil between the stainless steel corrugated diaphragm and the chip.
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Chinese name piezoresistive pressure sensor working principle
外文名压力传感器的工作原理
an introduction to theory
Piezoresistive pressure sensor working principle
The sensitive chip of the semiconductor material is encapsulated in the housing of the corrugated stainless steel membrane by ISO technology, and silicone oil is filled between the corrugated stainless steel membrane and the chip. The chip lead leads through the shell and adopts sealing measures to prevent the silicone oil from leaking out or the outside pressure medium from penetrating into it, so that the chip, the silicone oil, the shell and the lead constitute a pressure sensor. When the sensor is in a pressure medium, the medium pressure acts on the corrugated diaphragm to pressure the silicone oil in it, and the silicone oil transfers the pressure of the diaphragm to the semiconductor chip. When the chip is pressed, its resistance value changes, and the resistance signal is drawn out through the lead. The corrugated stainless steel diaphragm housing is pressurized and protects the chip, so the piezoresistive pressure sensor can sense pressure signals in aggressive media.
Piezoresistive pressure sensors are generally connected to Wheatstone Bridges through leads. Usually, the sensitive chip has no external pressure effect, and the bridge is in a balanced state (called zero position). When the chip resistance changes after the sensor is pressurized, the bridge loses balance. If a constant current or voltage supply is added to the bridge, the bridge will output an electrical signal corresponding to the pressure, so that the resistance change of the sensor is converted into a pressure signal output through the bridge.
Because of the pressure fluctuations caused by the air flowing in the intake manifold, the measurement accuracy using the pressure sensor is not high, but the manufacturing cost of the control system is lower. Many EFI engines do not use an air flow meter but a manifold pressure sensor, which together with the crankshaft position sensor determines the basic fuel supply for engine operation.
In general, the sensor of the air volume measurement method can be divided into two types, the intake manifold pressure sensor (i.e. negative pressure type) and the air flow sensor. The pressure sensor detects the absolute pressure in the intake manifold, and the measurement method is indirect.