Proximity sensors are used to detect the presence of any unwanted objects within their field of operation, by several mechanisms such as magnetic triggers, electromagnetic induction circuits and capacitors. Proximity Sensors make no actual physical contact, but assess data remotely transmitted by any object that intrudes into or moves within their range. This data is converted into an electrical signal that then provides an automatic response or activates an alarm to alert human intervention.

What are Proximity Sensors?

Proximity sensors are produced in five main categories:

• Magnetic sensors are believed to be the oldest historically, and can be used to actuate a magnetic field in pneumatic processes. These sensors are designed to detect the intermediate or end positions of a pneumatic cylinder stroke, but can also be used to identify ferrous (iron) particles in similar applications.
• Electromagnetic inductive sensors are most commonly found in applications where the main focus is the detection of metallic particles or objects.
• Capacitive sensors are used for detecting both metallic and non-metallic particles and objects, and most frequently in flow processes for grains, liquids, powders and plastics.
• Ultrasonic sensors function by means of sound resonance, and offer extreme precision for almost any conceivable application. This type of sensor is immune to contact abrasion or contamination by foreign objects.
• Photoelectric sensors have many uses where light can be used as a trigger, starting with a simple sound alarm that is triggered by a light-beam interruption when some margin is crossed.