Capacitive Level Sensor

elobau, a leader in the development of non-contact sensors, is currently prototyping a new capacitive level sensor. The sensor is designed for use in various tank level applications including food equipment, and mobile fluid containers and medical.

With our new prototypes elobau’s solution allows customers to accurately measure the level of fluids from outside the tank.
 

Prototype 1 – Up to four discrete switching points available

Prototype 2 - Analog continuous level monitoring with power supply and LEDs,

The advantages of Non-contact to fluid

• No mechanical parts
• High lifetime, no wear
• Fluid is not contaminated (by sensor)
• Simple replacement in case of defect
• Suitable with plastic- and glass containers
• Adhesion can be recognized
• Limit level detectors are more robust in case of deviations compared to continuous level sensors.
• With continuous level sensors there is a self calibration common with the first operation

The actual Capacitive Level Sensor operation is as follows:

The liquid is known as the dielectric. The key property of dielectric materials is the dielectric constant or relative permittivity. This property is the amount of charge the liquid can absorb.
 

As the liquid is introduced near the electrodes of the capacitor the capacitance changes progressively and liquid level can be determined. To measure variations in capacitance electric energy flowing into and out of the electrodes is measured as the circuit potential is varied. A regular flow of energy is established by connecting the electrodes to an alternating current measurement circuit. The more energy flow to the electrodes, the greater the capacitance, meaning more liquid between the electrodes.
 

For sensor calibration reference measurements at empty and full must be taken. Generally, we need to know the dielectric constant of the liquid being measured to calibrate the sensor at its full condition. With the empty and full outputs are established, liquid level sensing comes to relating sensor output to these values.

Capacitive Sensor Protoype Datasheet

Application information: Tell us about your application

As our product is currently in development its possible to demonstrate the function with initial samples but we are also asking for your feedback. Please fill out the form and tell us about your application: