Working principle of capacitive sensors
Capacitive sensors, also known as capacitive level gauges, operate on the principle of a cylindrical capacitor. The capacitor consists of two insulated, coaxial cylindrical plates, an inner electrode and an outer electrode. When an electrolyte with a dielectric constant ε is filled between the two cylinders, the capacitance between them is given by the formula: L = (D/e) * C * D * D * e ...
Capacitive sensors use various types of capacitors as sensing elements. Changes in the measured quantity cause changes in the capacitor's capacitance. A measuring circuit converts these capacitance changes into an electrical signal output. By measuring the magnitude of this electrical signal, the magnitude of the measured quantity can be determined. This is the basic working principle of capacitive sensors.
Applications of capacitive sensors
Capacitive sensors have advantages such as simple structure, high temperature resistance, radiation resistance, high resolution, and good dynamic response characteristics, and are widely used in the measurement of pressure, displacement, acceleration, thickness, vibration, and liquid level. However, the following factors should be noted regarding their impact on the measurement results during use:
1. Reduce changes in ambient temperature and humidity (which may cause changes in the dielectric constant of certain media or the geometric dimensions and relative positions of the plates);
2. Reduce edge effects;
3. Reduce parasitic capacitance;
4. Use shielded electrodes and ground them (to protect the electric field of sensitive electrodes and isolate them from external electric fields);
5. Pay attention to leakage resistance, excitation frequency, and the insulation of the electrode support material.
