Pressure sensors are one of the most widely used sensors. Traditional pressure sensors are mainly mechanical structure devices, and the deformation of elastic elements indicates the pressure, but this structure is large in size and heavy in weight, and cannot provide electrical output. With the development of semiconductor technology, semiconductor pressure sensors have also come into being. It is characterized by small size, light weight, high accuracy and good temperature characteristics. In particular, with the development of MEMS technology, semiconductor sensors are developing towards miniaturization, and their power consumption is low and reliable.
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Introduction to the working principle of several common pressure sensors:
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1. Piezoresistive pressure sensor
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Resistive strain gauges are one of the main components of piezoresistive strain transducers. The working principle of metal resistance strain gauge is the phenomenon that the resistance value changes due to mechanical deformation due to the strain resistance adsorbed on the base material, which is commonly known as the resistance strain effect.
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2. Ceramic pressure sensor
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The ceramic pressure sensor is based on the piezoresistive effect, the pressure directly acts on the front surface of the ceramic diaphragm, so that the diaphragm produces a slight deformation, the thick film resistor 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 to 2.0/3.0/3.3mV/V according to the different pressure ranges, etc., which can be compatible with strain gauge sensors.
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3. Diffusion silicon pressure sensor
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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 this pressure.
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4. Sapphire pressure sensor
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Using the strain resistance operating principle, silicon-sapphire is used as a semiconductor sensitive element with unmatched metering characteristics. Therefore, semiconductor sensitive components made of silicon-sapphire are not sensitive to temperature changes and have good working characteristics even under high temperature conditions. Sapphire has strong radiation resistance; In addition, silicon-sapphire semiconductor sensitive components have no p-n drift.
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5. Piezoelectric pressure sensor
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The piezoelectric effect is the main operating principle of piezoelectric sensors, which cannot be used for static measurements because the charge after the action of 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.
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