What are the basic principles of capacitive sensors?

The sensing surface of the capacitive sensor consists of two coaxial metal electrodes, which form a capacitor and are connected in series in the RC oscillation circuit. When the power is turned on, the RC oscillator does not oscillate. When a target approaches the sensor surface, the capacitance increases and the oscillator starts to oscillate. It is converted into a switch signal through the processing of the downstream circuit, thereby achieving the purpose of detecting the presence or absence of objects. Capacitive sensors can detect metal objects as well as non-metallic objects. For metal objects, they can obtain a suitable large operating distance. For non-metallic objects, the operating distance depends on the dielectric constant of the material. The greater the dielectric constant of the material, the greater the operating distance. The greater the action distance.