Introduction to Photoresist Sensor of Photoelectric switch

The optical resistance sensor of photoelectric switch refers to the sensor made of the piezoresistive effect of monocrystalline silicon material and integrated circuit technology.





The photoresist effect means that when the force acts on the silicon crystal, the lattice of the crystal deforms to scatter the carrier from one energy valley to another, which changes the mobility of the carrier and affects the average longitudinal and transverse amount of the carrier. Thus, the resistivity of silicon changes. This change varies with the orientation of the crystal, so the piezoresistive effect of silicon is related to the orientation of the crystal.



The resistivity of monocrystalline silicon material will change after being subjected to force, and the electrical signal output proportional to the force change can be measured by measuring circuit, and results contribute to analyze the magnitude of the applied force accordingly.



The diffusion silicon optical force sensor integrates the resistance strip on the monocrystalline silicon film by integrated process, and makes the silicon photoresist chip, which is fixed in the shell, and then leads out the electrode lead, so that the measured external force can be felt through the silicon film. One side of the silicon film is a high-pressure cavity connected with the measured pressure, and the other side is a low-pressure cavity connected with the atmosphere. There are four resistance bars connected to the whole bridge in the silicon film domain, two of which are located in the light stress region and two in the tensile stress region, which are symmetrical relative to the center of the diaphragm.



The principle of photoresistor sensor is to convert the input mechanical strain into resistance value change. The input of resistance converter is the relative change of material length, it is a relative value without denier, and the output of resistance converter is the relative change of resistance value.



To measure other physical quantities, strain gauge will be put the on the corresponding elastic element, convert the change of these physical quantities into the strain of the elastic element, and finally convert the strain into the resistance output through the strain gauge.



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