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Capacitive Proximity and Touch Sensor


GEOMATEC has created a capacitive proximity and touch sensor that uses a transparent substrate as the detector. Both the material and dimensions of these detectors can be customized to meet your needs. Please feel free to contact us.

What is a capacitive proximity and touch sensor?

A capacitive proximity and touch sensor is a sensor that detects changes in the capacitance of an object. Capacitance is the quantity of electrical charge that a conducting body holds when voltage is applied. When an object enters this electric field (space in which voltage is applied), the object becomes polarized (see figure below).


The degree of polarization depends on various factors, such as the distance between the electrode and the object as well as the size, thickness, and relative permittivity (*1) of the object. The greater the polarization in the object, the greater the electrical charge buildup on the electrode side will be.
The capacitive proximity and touch sensor operates by detecting this change in quantity of electric charge.

*1 Relative permittivity: degree of polarization of electrical charges in an object; materials containing large amounts of conducting body or water have high relative permittivity.

Example of capacitive proximity and touch sensor system

With the capacitive proximity and touch sensor in the photo on the left, the lamp beneath the transparent dome lights up when the sensor detects a person approaching. The configuration is designed so that the light grows brighter as the person moves closer. The light fades and the lamp switches off when the person moves out of range.

Detector: transparent dome comprising a transparent conductive film
Converter: LED light


Features of the capacitive proximity and touch sensor

The capacitive proximity and touch sensor grows brighter when the relative permittivity of the approaching object is higher. The sensor does not respond to objects that have low relative permittivity.
Sensor activation depends on the distance between the detector and the object and is unaffected by the presence of other objects in between (objects having low relative permittivity, such as paper or dry wooden board).

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A paper tube held near the sensor A conducting body inside a paper tube held near the sensor
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The detector (sensor) features an ultrathin lightweight design.

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The transparent conductive film can be formed on almost any kind of material and in any shape, including glass substrates or plastic rods.


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