Capacitive Linear Position Sensors Information

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Capacitive linear position sensors measure position, displacement, vibration, and run out (thickness), primarily in a noncontact manner. They have good accuracy and very high resolution, but may be sensitive to environmental factors.




Noncontact capacitive sensors measure changes in capacitance. Capacitance describes how two objects with a space between them respond to a voltage difference applied to them. This video illustrates:


Video Credit: Pebble Soup



One type of capacitive sensor features conductive probe and target objects.

Image Credit: Machine


For nonconductive targets, a stationary target plate may be used. When the nonconductor is placed between the probe and the target, the thickness, density, and/or position of the material changes the dielectric constant of the interval space.

Image Credit: Lion Precision


In cases of nonconductive sensing without a reference, the sensing electric field wraps back to the probe, creating a "fringe field." When a nonconductive material nears the probe, its ectric changes the field.

Image Credit: Lion Precision


Specifications and Features

  • Measurement ranges vary (e.g. 0.004 to 0.35 inches).
  • Sensing frequency varies (e.g. 0.42 to 26 kHz).
  • Electrical output signals can be analog (current, voltage, or frequency), digital (serial, parallel, or other), an alarm, or a change in state of switches.
  • Packaging varies from none (a sensor element) to housed (transducer). Instruments or meters are self-contained and display output at or near the device. A gauge or indicator has an analog display and no electronic output.
  • Devices can tolerate maximum shocks, maximum vibrations, and certain temperature ranges (e.g. -100 to 1832°F).
  • Recorders and totalizerscan be added to collect and store data locally.



Capacitive sensors measure position (automation, semiconductor processing, disk drives), dynamic motion (tool spindles, disk drive spindles, high-speed drill spindles, ultrasonic welders), and thickness (silicon wafer, brake rotor, disk drive platter, label positioning). They also can perform assembly testing.




Capacitive Sensors-An Overview

Capacitive Sensor Operation and Optimization (How Capacitive Sensors Work and How to Use Them Effectively)

Capacitive Sensors

Finding the Right Sensor for Linear Displacement


Image Credits:  MTI Instruments

Related Products & Services

  • Eddy Current Linear Encoders

    Eddy current linear encoders detect the distance from a target by using magnetic fields generated by a reference and sensing coils.

  • Linear Variable Differential Transformers (LVDT)

    Linear variable differential transformer (LVDT) linear position sensors have a series of inductors in a hollow cylindrical shaft and a solid cylindrical core. These devices produce an electrical output proportional to the position of the core

  • Optical Linear Encoders

    Optical linear encoders use fiber optic technology to sense position and displacement.

  • Optical Triangulation Position Sensors

    Optical triangulation position sensors use reflected waves to pinpoint position and displacement. The source of these waves may be a light emitting diode (LED), infrared (IR) light, or laser.

  • Photoelectric Sensors

    Photoelectric sensors use emitters and receivers to detect the presence, absence, or distance of target objects.

  • String Potentiometers

    String Potentiometers are used to measure the movement and displacement of objects. A cable or wire is attached to an object, and as the object moves, the transducer produces an electrical signal proportional to the wire's linear extension.

  • Ultrasonic Linear Position Sensors and Switches

    Ultrasonic linear position sensors and switches use ultrasonic waves in combination with light and frequency readings for position and displacement sensing.