Proximity sensors measure distances without requiring physical contact with the object being measured. Proximity sensing utilizes various forms of technology. All proximity sensors emit a field, and an object, often called the target, triggers the sensor when it enters the field. The type of target object dictates the kind of proximity sensor you need. Inductive proximity sensors are ideal for metallic objects while capacitive sensors detect non-metallic objects.

Proximity sensors are frequently used in the security industry to control access door and gates, as well as in industrial machinery applications. Sensors typically detect a predetermined distance, called the nominal range, although some sensors allow the nominal range to be adjusted. When purchasing proximity sensors, consider the following:

1. Check the proximity sensor info or specifications to be sure it can detect your target objects.

2. Use inductive proximity sensors when detecting metallic objects.

3. Know that microwave sensors are capable of detecting through walls.

Action Steps
The best contacts and resources to help you get it done

Purchase inductive proximity sensors

An inductive proximity sensor operates by setting up a radio frequency field with an oscillator and a coil. When an object enters the radio frequency field, the sensor detects the alteration in the field. Inductive proximity sensors are used in various applications, including security, machine and process control, level detection and valve position.

I recommend: Order one of four models of inductive proximity sensors from wenglor sensoric. The company manufactures standard inductive proximity sensors, inductive all-metal sensors, inductive full metal sensors and analog inductive sensors. Spectec offers inductive proximity sensors with near-zero speed sensing. The units are available in a variety of sizes.

Order microwave proximity sensors

Microwave proximity sensors aren't inhibited by distance or physical barriers. A microwave proximity sensor detects moving targets and can do so from great distances and through walls. The sensors are also used for security, as well as in applications such as paper making and textiles.

I recommend: Browse an inventory of microwave sensors at Steven Engineering. The sensors are available in different styles, sizes and configurations, and the company offers same-day shipping. NDC Infrared Engineering is a custom manufacturer of microwave sensors.

Use capacitive proximity sensors

A capacitive proximity sensor detects the distance between the sensor's face plate and the target object. The sensor's plate and the object function as the two capacitors, and the capacitance varies inversely with the distance between the capacitors. The operator sets the value at which the proximity sensor is triggered.

I recommend: Order a custom capacitive proximity sensor from ISSC-Kanson Electronics. The company also offers proximity switch accessories, such as bracket and adapters. Fargo Controls offers capacitive proximity sensors that detect metallic and non-metallic objects from distances ranging from 0 to 35mm. Browse capacitive proximity sensors in a variety of sizes and specifications at Turck.

Implement magnetic proximity sensors

Magnetic proximity sensors are non-contact units and can be placed away from the extreme conditions they're monitoring. The units detect distance by using Hall effect principles, inductance and variable reluctance.

I recommend: Purchase a custom magnetic proximity sensor from Smith Systems. The units are compatible with digital equipment and powered with a wide range of supply voltages. EMX Industries offers several models of magnetic proximity sensors. EMX sensors are used in a wide range of industries, including automotive, packaging, plastics and metal stamping.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Proximity sensors are available in several types of body styles, with the most common being tubular and block styles. Tubular styles are threaded for easy installation and block styles are simplistic and inconspicuous.