Capacitive sensors – find manufacturers and suppliers

Capacitive sensors are non-contact measuring devices that detect changes in electrical capacitance in order to detect the presence or distance of objects, regardless of whether they are conductive or non-conductive.

They are widely used in industry and are used for non-contact detection of a wide variety of materials. In contrast to inductive sensors, which only react to metallic objects, capacitive sensors can detect both metallic and non-metallic objects, such as plastics, liquids, glass or wood.

Below you will find the functionality and typical designs of capacitive sensors, their areas of application and their advantages, as well as the challenges that need to be considered when using them:

How capacitive sensors work:

1. Capacitive sensors consist of two electrodes that generate an electric field.
2. When an object enters the electric field, the capacitance between the electrodes changes.
3. This change is detected by the sensors and converted into a switching signal.
4. Capacitive sensors can detect both conductive (metallic) and non-conductive (non-metallic) materials, which makes them versatile in many applications.

Typical designs of capacitive sensors:

1. Like inductive sensors, capacitive sensors are often available in cylindrical designs (e.g. M12, M18), which makes them easy to use in many standard applications.
2. Flat, rectangular sensors are also available for applications where compact installation is required.
3. Many capacitive sensors are equipped with adjustable sensitivity and integrated circuits to adapt the responsiveness to the respective application.

Typical areas of application for capacitive sensors:

1. Level measurement:
Capacitive sensors are often used to monitor fill levels in containers and tanks. They can detect liquids (water, oil, chemicals) and bulk materials (grains, powders, granulates) through container walls.

2. Position detection:
Like inductive sensors, capacitive sensors are also used for position detection, but with the advantage that they can detect not only metallic but also non-metallic objects (e.g. glass, paper, plastic).

3. Distance measurement:
In applications where the distance between an object and a sensor is crucial, such as in quality control or production processes, capacitive sensors can be used for precise distance measurement.

4. Detection of objects through materials:
Capacitive sensors can detect objects through non-conductive materials such as plastic, glass or paper. This makes them ideal for applications in which the object to be detected lies behind a barrier.

5. monitoring objects in packaging:
They are used in the packaging industry to ensure that packages are correctly filled or products are present.

Advantages of capacitive sensors:

• Capacitive sensors can detect both metallic and non-metallic materials, making them more versatile than inductive sensors.
• Like inductive sensors, capacitive sensors are non-contact, which protects them from mechanical wear.
• Capacitive sensors can also detect objects through thin, non-conductive materials such as plastic or glass walls.
• They react sensitively to dielectric materials, which is advantageous for special applications such as fill level detection.

Challenges of capacitive sensors:

• Capacitive sensors can be sensitive to moisture, dust or dirt, as these factors can affect the capacitance in the electric field.
• The detection range can be significantly lower with non-conductive materials, such as plastic or glass, than with conductive objects.

Capacitive sensors are an excellent choice when non-contact detection of different materials is required, especially when non-metallic materials are involved. They are ideal for applications such as level measurement, position and distance monitoring, and are indispensable in many industries.

Below you will find an overview of the most important criteria to look out for when purchasing capacitive sensors:

When purchasing capacitive sensors, there are several important factors to consider to ensure that the sensor is suitable for the specific application.

• The nominal sensing distance indicates how far the sensor can detect an object. Non-conductive materials (such as plastic or glass) have a shorter range than conductive materials (such as metals or water). Typical ranges are between 1 mm and 25 mm.
• Make sure that the range of the sensor is sufficient to reliably detect the objects to be detected. Take the material properties of the object into account.
• Metals and liquids offer a greater detection range.
• Plastic, wood, glass and paper have a shorter range.
• If the target object is made of non-conductive materials, select a sensor with a higher nominal range to ensure reliable detection.
• Select the design according to the spatial conditions of your system. The size can also influence the detection range - larger sensors often have a greater detection range.
• Cylindrical sensors are often available in standard sizes such as M12, M18 or M30 and are well suited for universal applications.
• Cuboid sensors are better suited for tight installation spaces or special mounting situations.
• Many capacitive sensors offer the option of manually adjusting the sensitivity to adapt the detection performance to the target object and the ambient conditions.
• If your application needs to detect different materials with varying dielectric constants, a sensor with adjustable sensitivity is advantageous.
• Select the switching type according to the required logic of your control system or machine control.
• Normally open (NO): The sensor gives a signal when an object is detected.
• Normally closed (NC): The sensor emits a signal when no object is detected.
• Switchable (NO/NC): Some sensors offer both options and are switchable.
• Make sure that the supply voltage of the sensor matches the voltage of your system.
• DC sensors (direct voltage): Typically 10-30 V DC, which is used in many industrial applications.
• AC sensors (alternating voltage): These often operate in the range of 20-250 V AC.
• Multi-voltage sensors: Some sensors support both DC and AC.
• Take into account the speed of movement or passage of the object to be detected. If you need fast switching, make sure the sensor supports the required frequency.
• Capacitive sensors have a lower switching frequency compared to inductive sensors, so they are often used to detect slow-moving or static objects. Nevertheless, they can be used reliably in many applications.
• Capacitive sensors can react to environmental conditions that affect their performance, as moisture or dust can influence the capacitance measurement.
• Use sensors with appropriate protection mechanisms (e.g. IP67 or IP68) if they are used in harsh environments or under difficult conditions.
• IP67: Protected against the ingress of dust and temporary immersion in water.
• IP68: Provides protection against permanent immersion in water.
• Select the appropriate mounting type for your application to minimize interference from surrounding objects.
• Capacitive sensors can be flush or non-flush mounted. With flush mounting, the sensor is completely integrated into the surface, while with non-flush mounting, the sensor protrudes slightly.
• Most capacitive sensors operate in a temperature range from -25 °C to +70 °C, special models also support larger temperature ranges.
• Sensors with a permanently connected cable are suitable for applications where frequent maintenance or sensor replacement is not required.
• Connectors (M8 or M12) offer flexibility, especially if the sensor needs to be replaced or serviced frequently.
• Don't choose the cheapest sensor, but make sure it meets the requirements of your application. A reliable, durable sensor will save costs in the long term due to fewer failures and maintenance.
• For demanding applications, choose sensors with these additional features to optimize performance.
• If the sensor needs to work through non-conductive materials such as glass or plastic, make sure the sensor is suitable for this.
• Adjustable detection: Some sensors offer potentiometers or digital settings to fine-tune the detection range.

When purchasing capacitive sensors, it is crucial to consider the specific requirements of the application. Important factors are the detection range, the material to be detected, the design, the environmental influences as well as the supply voltage and protection class. A well-chosen capacitive sensor ensures a reliable and durable solution, especially in applications where different materials need to be detected.

Capacitive sensors can be obtained from various suppliers. Comprehensive information about manufacturers and suppliers of Capacitive sensors from all over the world can be found on Exportpages.