What is Capacitive Sensor?

What is Capacitive Sensor?

Capacitive sensor definition

Capacitive sensor is a kind of sensor based on capacitance change to detect the change of physical quantity.

Working principle

The working principle of capacitive sensors is based on the definition formula of capacitance:

• C is capacitance.

• ϵ is the permittivity of the medium.

• A is the effective area between the plates.

• d is the distance between the two plates.

Capacitive sensors detect changes in physical quantities by changing one or more of these three parameters. Specifically, the output capacitance C of the capacitive sensor will change with the change of the physical quantity to be measured, so as to achieve the detection function.

Type

• Variable-area type

• Type variable clearance

• Variable dielectric constant type

Advantage

• High sensitivity: Can detect small changes in physical quantities.

• Fast response time: Very short response time to change.

• Simple structure: usually composed of a simple metal plate or foil.

• Non-contact measurement: can not directly contact the measurement under the condition of object to be tested.

• Wear resistance: no moving parts, not easy to wear.

Shortcoming

• Temperature effect: Temperature changes affect the dielectric constant of the medium, which affects the accuracy of the sensor.

• Nonlinear: Some types of capacitive sensors have nonlinear problems.

• Interfere with sensitive, vulnerable to electromagnetic interference of surrounding environment.