Capacitive proximity sensors
A proximity sensor that
maintains a certain distance from the object to be tested and can detect
non-contact. It can be used to detect small displacements by taking advantage
of the fact that the capacitance between the object to be tested and the sensor
is inversely proportional to the distance between the two. This sensor has a
simple structure and high detection accuracy, but its disadvantages are that it
is difficult to machine, has high output impedance, and is easily affected by
stray capacitance.