1. CAPACITANCE SENSOR

2. Capacitance Sensor
It is based on the capacitance of a parallel plate capacitor.
Variable Capacitance type
It varying distance between two or more parallel electrodes.
Variable area between the electrodes.
Variable dielectric constant materials.

3. Parallel Plate Capacitance Sensor
the ability of a substance to store electrical energy in an electric field.
Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum.

4. Capacitance Value

5. Equivalent Circuit of Capacitance Transducer

6. Parallel plate Capacitive sensor

7. Serrated Plate Capacitive Sensor

8. Variable Permittivity or Variable Thickness Dielectric Capacitive Sensor

9. Advantage Extremely sensitive Good frequency response
High input impedance
Loading effects are minimum
Small forces to operate them use in small systems.

10. Disadvantage
Metallic parts must be insulated each other (reduce the effect of stray capacitances), frame must be earthed.
Non linear behavior many a times on account of edge effects. (guard ring used eliminate this effect)
Cable connecting the sensor to the measuring point is also a source of error.

11. Applications Measurement of both linear and angular displacement.
Force and pressure
Humidity in gases
Volume, density, liquid level, weight.