Introduction to strain gauge sensors
There are many kinds of pressure sensors, such as resistance strain gauge pressure sensor, semiconductor strain gauge pressure sensor, piezoresistive pressure sensor, inductive pressure sensor, capacitive pressure sensor, resonant pressure sensor and diaphragm electrode pressure sensor. But the most widely used is the resistance strain gauge pressure sensor, which has a very low price, high accuracy and better linear characteristics. It is composed of a base material, a metal strain wire or strain foil, an insulation protection sheet and an outlet line. According to different uses, the resistance value of the resistance gauge can be designed by the designer, but the value range of the resistance should be noted: the resistance value is too small, the required drive current is too large, and the heating of the strain gauge causes its own temperature to be too high, which is used in different environments, so that the resistance value of the strain gauge changes too much, the output zero drift is obvious, and the zeroing circuit is too complex. The resistance is too large, the impedance is too high, and the ability to resist external electromagnetic interference is poor. Generally, it is about tens of euros to tens of thousands of euros.
Working principle of strain gauge sensor
The resistance strain gauge pressure sensor is a sensor which is composed of a measuring circuit and an elastic sensor. When the elastic sensitive element is subjected to pressure, it will produce strain, and the resistance strain gauge pasted on the surface will also produce strain, which is manifested as a change in resistance value. Thus, the deformation of the elastomer is translated into a change in the resistance value of the resistance strain gauge. The four resistance strain gauges are connected in bridge mode. A certain voltage value is applied to the two input terminals, and the common mode voltage output by the two output terminals increases or decreases with the change of the resistance value on the bridge. In general, the corresponding relation of such changes is approximately linear. By finding the correspondence between the pressure change and the output common mode voltage change, the pressure value can be obtained by measuring the common mode voltage.
