Allen-Bradley makes several types of proximity sensors for detecting solids or liquids including general purpose and plastic barrel tubular capacitive models, inductive sensors for welding, harsh duty, and more, and ultrasonic proximity sensors.

Baumer Electric manufactures several ultrasonic proximity sensors for general, electrical, and mechanical data in varying sensing ranges from 10 to 200mm and a scanning range of 20 to 200mm.

Instronics offers ultrasonic proximity sensors that are stud-mountable, self-contained and offer 120VAC power as well as ranges of 5 to 30 or 10 to 72 inches with a narrow sensing beam, high frequency, LED indicator, and more.

Pepperl & Fuchs makes capacitive, hall effect, inductive, magnetic, and ultrasonic proximity sensors in cylindrival and rectangular housing styles as well as reed door sensors.

Siemens makes Simatic brand proximity sensors including inductive, photoelectric, ultrasonic, capacitive, and totally integrated models with applications including position measurement, color recognition, prescence detection, and absence counting.