Resistive sensors are sensors that convert non-electrical physical quantities such as displacement, force, pressure, acceleration, torque, etc. into changes in electrical resistance. It mainly includes resistance strain sensors, potentiometer sensors (see displacement sensors) and manganese copper piezoresistive sensors.
Structure of resistive sensors
The structure of resistive sensors consists of two basic parts: the resistive element and the brush (movable contact). The movement of the brush relative to the resistive element can be linear, rotational and spiral movement, and thus can be converted into a linear displacement or angular displacement with a certain function of the resistance or voltage output. The following is the structure and material of the potentiometer:
1, resistance wire: copper wire, platinum-iridium alloy and Karma wire, etc.
2, brush: commonly used silver, platinum-iridium, platinum-rhodium and other metals
3, skeleton: commonly used materials for ceramics, phenolic resin, clamped cloth and other insulating materials such as wood, the skeleton of the structure of many forms, commonly used rectangular.
Resistive sensor advantages
1, there is a large nonlinearity, the output signal is weak, but can take certain compensation measures. Therefore, it is widely used in automatic testing and control technology.
2, resistance strain sensors in the resistance strain gage has a metal strain effect, that is, under the action of external forces to produce mechanical deformation, so that the resistance value with the corresponding changes
Disadvantages of resistive sensors
1, for large strains have greater nonlinearity, but the output signal is weak.
2, with time and environmental changes, the composition of the sensor material and device performance will change. Therefore, it is not suitable for long-term monitoring, because the time drift, temperature drift is large, long time measurement may not be able to obtain real and effective data.
3, susceptible to electric fields, magnetic fields, vibration, radiation, air pressure, sound pressure, airflow and other influences.
Resistive sensors and the corresponding measurement circuit composed of force, pressure, weighing, displacement, acceleration, torque and other measuring instruments are metallurgy, electric power, transportation, petrochemical, commercial, biomedical and defense sectors for automatic weighing, process detection and automation of the production process is one of the indispensable tools.