Capacitive pressure sensor is a pressure sensor that uses capacitance as a sensitive element to convert the measured pressure into a change in capacitance value.This kind of pressure sensor generally uses a circular metal film or a metal-plated film as an electrode of the capacitor.When the film is deformed by pressure, the capacitance formed between the film and the fixed electrode changes, and an electrical signal that has a certain relationship with the voltage can be output through the measuring circuit.Capacitive pressure sensors belong to the polar distance variable capacitive sensors, which can be divided into single capacitive pressure sensors and differential capacitive pressure sensors.
The single capacitive pressure sensor consists of a circular membrane and a fixed electrode.The film deforms under pressure, thereby changing the capacity of the capacitor,The sensitivity is roughly proportional to the area and pressure of the membrane and inversely proportional to the tension of the membrane and the distance from the membrane to the fixed electrode.Another type of fixed electrode takes the shape of a concave spherical surface, and the diaphragm is a tension plane fixed around the periphery.This type is suitable for measuring low pressure and has a high overload capacity.A single-capacitive pressure sensor for measuring high pressure can also be made of a diaphragm with a piston moving pole.This type can reduce the direct pressure area of the diaphragm, so that a thinner diaphragm can be used to improve the sensitivity. It is also integrally packaged with various compensation and protection sections and amplifier circuits to improve anti-jamming capability.This sensor is suitable for measuring dynamic high pressure and for telemetry of aircraft. There are also types of single capacitive pressure sensors such as microphone type (ie microphone type) and stethoscope type.
The pressure-receiving diaphragm electrode of the differential capacitive pressure sensor is located between two fixed electrodes, forming two capacitors.Under the action of pressure, the capacity of one capacitor increases and the other decreases accordingly, and the measurement result is output by the differential circuit.Its fixed electrode is made of metallized layer on the concave curved glass surface. The diaphragm is protected against rupture by the concave surface when overloaded.Differential capacitive pressure sensor has higher sensitivity and better linearity than single capacitive pressure sensor, but it is more difficult to process (especially difficult to ensure symmetry), and it cannot achieve isolation of the gas or liquid to be measured, so it is not suitable for working in corrosive environments. sex or impurities in the fluid.
Post time: Apr-07-2022