nearsensor

A nearsensor, typically called a proximity sensor, detects the presence or absence of nearby objects without physical contact. The term is used in some contexts to distinguish proximity sensing from touch sensors. A nearsensor measures changes in an electrical, magnetic, optical, or acoustic field caused by a nearby object, enabling a detected event or measurement.

Common technologies include infrared optical sensors (emitting and receiving light to detect reflections), capacitive sensors (changes in capacitance due to an approaching object), inductive sensors (electromagnetic field perturbations for ferrous materials), ultrasonic sensors (time-of-flight of sound), and RF or radar sensors (reflected waves). Each type has different ranges, resolutions, and material dependencies.

Operation can produce digital (on/off) or analog distance signals. Sensing ranges vary: infrared and capacitive/inductive sensors often from millimeters to a few centimeters; ultrasonic from centimeters to meters; radar from meters. Many devices require calibration or environmental compensation for reliable operation.

Applications span consumer electronics (screen proximity and gesture input), automotive sensing, industrial automation, and robotics. Advantages include contactless operation, fast response, and low mechanical wear. Limitations involve environmental sensitivity, material dependence, potential false detections, and the need for power and calibration.

See also: proximity sensor, optical sensor, capacitive sensor, inductive sensor, ultrasonic sensor.