How does a proximity sensor work?

Inductive Proximity Sensors:

Inductive proximity sensors work based on the principle of electromagnetic induction.
These sensors generate an oscillating magnetic field using a coil or an inductor.
When a conductive object (metal) enters the sensing range of the sensor, it disturbs the magnetic field, causing a change in the inductance of the coil.
The change in inductance is detected by the sensor’s electronic circuitry, which triggers an output signal indicating the presence of the object.
Capacitive Proximity Sensors:

Capacitive proximity sensors operate based on changes in capacitance.
These sensors consist of two electrodes separated by a dielectric material (air or non-conductive material).
When an object enters the sensing range, it changes the capacitance between the electrodes due to its dielectric properties.
The change in capacitance is detected by the sensor’s circuitry, which generates an output signal indicating the presence of the object.
Ultrasonic Proximity Sensors:

Ultrasonic proximity sensors use ultrasonic waves (sound waves with frequencies above the audible range) to detect objects.
These sensors emit ultrasonic pulses and measure the time taken for the pulses to reflect off objects and return to the sensor.
The time-of-flight of the ultrasonic waves is proportional to the distance between the sensor and the object.
By analyzing the time delay, the sensor determines the presence and distance of the object within its sensing range.
Optical Proximity Sensors:

Optical proximity sensors use light-based techniques to detect objects.
These sensors typically consist of a light source (such as an LED) and a photodetector (such as a photodiode or phototransistor).
When an object enters the sensing range, it interrupts or reflects the light beam emitted by the sensor.
The change in light intensity detected by the photodetector triggers an output signal indicating the presence of the object.