Structure of resistive sensor
A resistive sensor consists of two basic parts: a resistive element and a brush (moving contact). The brush can move linearly, rotaryly, or helically relative to the resistive element, thus converting linear or angular displacement into a resistance or voltage output that has a specific functional relationship with it. Below is the structure and materials of a potentiometer:
1. Resistance wire: constantan wire, platinum-iridium alloy, and kamma wire, etc.
2. Brushes: Commonly used metals include silver, platinum-iridium, and platinum-rhodium.
3. Frame: Commonly used materials are ceramic, phenolic resin, and fabric-reinforced bakelite, etc. There are many structural forms of the frame, with rectangles being the most common.
Advantages and disadvantages of resistive sensors
Advantages of resistive sensors
1. It exhibits significant nonlinearity and a relatively weak output signal, but certain compensation measures can be taken. Therefore, it is widely used in automatic testing and control technologies.
2. The resistance strain gauge in a resistance strain gauge sensor exhibits the strain effect of metals, meaning that it undergoes mechanical deformation under external force, thereby causing a corresponding change in resistance value.
Disadvantages of resistive sensors
1. It exhibits significant nonlinearity for large strains, but the output signal is relatively weak.
2. The properties of the materials and components that make up the sensor will change with time and environmental changes. Therefore, it is not suitable for long-term monitoring because the time drift and temperature drift are large, and it may be impossible to obtain truly effective data over a long period of time.
3. It is susceptible to the effects of electric fields, magnetic fields, vibrations, radiation, air pressure, sound pressure, airflow, etc.
Resistive sensors, along with corresponding measuring circuits, are used to construct measuring instruments for force, pressure, weight, displacement, acceleration, torque, etc. These instruments are indispensable tools for automatic weighing, process monitoring, and production automation in sectors such as metallurgy, power, transportation, petrochemicals, commerce, biomedicine, and national defense.
