A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor’s target.
Different proximity sensor targets demand different sensors. You can get here Autonics Sensor Proximity Sensor, Generic Proximity Sensor. Autonics Sensor includes capacitive proximity Sensor and inductive proximity Sensor with Operating Voltage 10VDC ~ 30VDC and different Detection Distance, Output Type, Outer Thread Size etc… Capacitive proximity sensor suitable for a plastic target an inductive proximity sensor always requires a metal target.