Capacitive Sensor: Advantages and Disadvantages

This page explores the advantages and disadvantages of capacitive sensors.

Definition of a Capacitive Sensor: A capacitive sensor is a device that uses capacitive coupling to detect and measure objects. It can detect conductive materials or materials with a dielectric constant different from air. For example, in liquid level sensing, changes in the liquid between two sensors alter the dielectric material, causing a variation in capacitance.

The capacitance of two parallel plates with Area (‘A’) and separated by distance (‘d’) is expressed as follows:

A major application of capacitive sensors is level sensing, as mentioned above.

Advantages of Capacitive Sensors

Following are the advantages of Capacitive sensors :

• It can be used to detect non-metallic targets.
• It can detect through containers of certain types.
• It is simple in construction and adjustable.
• It can detect dense targets and liquids.
• It is lower in cost.
• It has higher sensitivity and can be operational with small magnitudes of force.
• It can be used for the measurement of force, pressure, and humidity.
• It has very good resolution (as low as 0.003 mm) and frequency response.

Disadvantages of Capacitive Sensors

Following are the disadvantages of Capacitive sensors:

• It is very sensitive to changes in environmental conditions such as temperature and humidity. This will affect performance.
• The measurement of capacitance is harder compared to the measurement of resistance.
• Capacitive proximity sensors are not as accurate compared to inductive sensor types.