Pressure sensor basics - solutions - Huaqiang Electronic Network

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Sensitive components are components that are sensitive to the measured variable and respond. For example, an elastic bellows can sense the level of pressure and cause deformation. The degree of deformation is that the response sensitive element to the pressure level is a component that can sensitively sense and respond to the measured variable. For example, the elastic bellows can sense the pressure and cause deformation. The degree of deformation is the response to the pressure. Therefore, the elastic capsule is a pressure sensitive component.
The sensor should not only be sensitive to the measurement, but also have the ability to transmit its response to the measurement. That is to say, the sensor is not only a general sensitive component, but its output response must also be a physical quantity that is easy to transmit. For example, the output response of the appealing elastic bellows is deformation, which is a small geometric amount and is not convenient for transmission to a distant place. If the displacement at the center of the capsule is changed to the gap change of the capacitor plate, it becomes a pressure sensor whose output response is capacitance.
Since electrical signals are most convenient to transmit, the output of most sensors is in the form of electrical quantities such as voltage, current, resistance, inductance, capacitance, frequency, and so on.
Transmitters are developed from sensors. Any sensor that outputs a standard signal is called a transmitter. (Standard signals are signals with physical quantities and values ​​that conform to international standards. For example, DC 4 to 20 mA.) With a uniform signal form and numerical range, it is easy to combine various transmitters and other instruments into a detection system or adjustment system. . (Electrician Forum http://)
Sensors that are output as non-standard signals must be matched to a specific meter or device for detection or adjustment. To enhance versatility and flexibility, the output of some sensors can be converted to a standard signal by a converter to match a meter with an input circuit or interface with a standard signal. Different standard signals can also be converted to each other by means of a converter. For example, a gas/electric converter can be used to convert an air pressure of 20 to 100 kPa into a direct current of 0 to 10 mA.
Positional effect and continuous action:
The positional effect, also known as the switching action, means that the sensor has only two states in its output over the entire range of the input variable, such as "high" and "low" of the air state.
The position-based sensors are mostly used for over-limit alarms, interlock protection, and sequence control of measured variables. For example our pressure switch.
When it is necessary to continuously detect or adjust certain variables, it is necessary to use a continuously acting sensor or transmitter.
The characteristics of the sensor SS-evaporation type semiconductor strain gauge used in Nagano's transmitter:
(1) Evaporation is a new technology with respect to paste type and diffusion type.
(2) The measurable pressure range is -0.1 to 0.3 MPa; 0 to 200 MPa.
(3) It has good durability and stability.
Semiconductor strain gauge manufacturing method: paste method, evaporation method, diffusion method.
Nagano's transmitters, such as KM31 and KM10, have a semiconductor strain gage section, an inductive component (stainless steel diaphragm) and a pressure interface part that are welded together to provide high stability and reliability, shock resistance and impact resistance. good.
The specific manufacturing method of the evaporative semiconductor strain gauge is as follows:
(1) Precipitating a layer of polysilicon on the SiO2 insulating film by depositing a SiO2 insulating film (2) on the stainless steel separator using CVD plasma.
(3) Laser etching is used on the polycrystalline silicon to form a strain gauge.
(4) Electrode beam evaporation was carried out, and a gold electrode was attached.
(5) A layer of SiNx protective film was deposited using CVD plasma.
Flameproof and intrinsically safe type are selected according to the non-flammable and explosive gas and the degree of danger of the sensor or transmitter installation site.
(1) The flameproof type adopts isolation measures between the internal circuit and the surrounding flammable gas, and is allowed to be used in a dangerous environment.
(2) Intrinsically safe type is the abbreviation of intrinsic safety type. It relies on specially designed circuit to ensure that it will not cause explosion accidents under normal working and faults (accident short circuit or open circuit). It can be used in places that are very flammable and explosive.