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.
