The working principle of pressure sensors mainly relies on the deformation of the shaft or diaphragm to measure the magnitude of pressure. When external pressure acts on the shaft or diaphragm, it will cause a certain degree of deformation. By accurately measuring this deformation, we can determine the value of the applied pressure. The working principle of pressure sensors can be divided into two types: resistive and capacitive. Resistance pressure sensors are based on the principle of resistance change for measurement, usually including elastic metal thin films、Components such as electrodes and base plates. When external pressure is applied, the elastic metal film undergoes deformation, causing a change in its surface resistance value. By measuring the change in resistance, we can determine the applied pressure. Capacitive pressure sensors use the principle of capacitance change for measurement, consisting of components such as electrostatic capacitance, aluminum film, and conductive adhesive. When external pressure is applied, the aluminum film and conductive adhesive are compressed, causing a change in capacitance value. By accurately measuring this capacitance change, the magnitude of the pressure it is subjected to can be inferred.

The wiring method of pressure sensors varies depending on the type of sensor and system requirements. Common wiring methods include two-wire and three wire systems、Four wire system, etc. Two wire wiring is relatively simple, and most customers know how to wire it. One wire is connected to the positive pole of the power supply, and the other wire, which is the signal wire, is connected to the negative pole of the power supply through the instrument. The three wire system adds a wire to the two wire system, which is directly connected to the negative pole of the power supply. The four wire pressure sensor definitely has two power input terminals, and the other two are signal output terminals. Four wire systems are mostly voltage outputs rather than 4-20mA outputs. 4-20mA transmitters are called pressure transmitters, and most are made into two-wire systems.