Analysis of the principle of pressure sensor

There are many types of sensors. Pressure sensors are the most common types of sensors in life. What is the working principle of pressure sensors? China's sensor trading network pointed out that pressure sensors are the most commonly used sensors in industrial practice. They are widely used in various industrial automation environments. Piezoelectric sensors are also widely used in biomedical measurements, such as ventricular catheter microphones. Made of piezoelectric sensors, because the measurement of dynamic pressure is so common, the application of piezoelectric sensors is very wide. The following briefly introduces some common sensor principles and their applications.

In understanding the piezoresistive force sensor, we first understand the element resistance strain gauge. The resistance strain gauge is a sensitive device that converts the strain change on the device under test into an electrical signal. It is one of the main components of a piezoresistive strain sensor. The most widely used resistance strain gauges are metal resistance strain gauges and semiconductor strain gauges.

Strain gauge pressure sensor principle and application of a wide range of mechanical sensors, such as resistance strain gauge pressure sensor, semiconductor strain gauge pressure sensor, level transmitter, input level transmitter, static pressure level transmitter, piezoresistance Pressure sensors, inductive pressure sensors, capacitive pressure sensors, resonant pressure sensors, and capacitive acceleration sensors. But the most widely used is the piezoresistive pressure sensor, which has a very low price, high accuracy and good linearity. Below we mainly introduce such sensors.

There are two kinds of wire strain gauges and metal foil strain gauges. Usually, the strain gauges are tightly bonded to a mechanical strain matrix through a special adhesive agent. When the stress of the base body changes, the strain gauges also deform together, so that the resistance of the strain gauges is changed. The voltage applied to the resistor changes. These strain gauges usually have a small change in resistance when they are subjected to stress. In general, these strain gauges form a strain bridge and are amplified by a subsequent instrumentation amplifier and transmitted to a processing circuit (usually A/D conversion). And CPU) display or actuator.

The internal structure of the metal resistance strain gauge The metal resistance strainer consists of a base material, a strained metal wire or a strain foil, an insulating protection sheet, and lead wires. According to different uses, the resistance of the strain gauge can be designed by the designer. Jiangsu Hengtai Instrument Co., Ltd. specializes in the production of instrumentation equipment. However, the value range of the resistor should be taken into account: the resistance is too small, the required drive current is too large, and at the same time the heat of the strain gauge causes its own temperature to be too high. Therefore, the resistance of the chip should be changed too much when used in different environments. The output zero drift is obvious, and the zero adjustment circuit is too complicated. The resistance is too high, the impedance is too high, and the resistance to external electromagnetic interference is poor. Generally, they are several tens of euros to several tens of thousands of euros.