How are capacitive sensors used in liquid level sensing?

How are capacitive sensors used in liquid level sensing?

As the liquid level changes, the amount of dielectric material between the plates changes, which causes the capacitance to change as well. A second pair of capacitive sensors (shown as C 2) is used as a reference. Figure 3. Capacitive level sensing.

What happens to capacitance when liquid level changes?

As the liquid level changes, the amount of dielectric material between the plates changes, which causes the capacitance to change as well. A second pair of capacitive sensors (shown as C 2) is used as a reference.

How can you monitor the level of a liquid?

A simple technique for monitoring liquid levels is to immerse a parallel-plate capacitor in the liquid, as shown in Figure 3. As the liquid level changes, the amount of dielectric material between the plates changes, which causes the capacitance to change as well.

What can a water level sensor be used for?

This sensor can be used for anything that has a large height of liquid to be measured, most notably the water level in hydro- and aquaponics setups and ponds. It is not accurate to a mm, but it can tell the height within 1-2cm, more than enough for most applications.

How is the dielectric of a liquid level sensor created?

The sensor board is designed using two coplanar metal plates instead of two parallel plates. With parallel plates on a PCB, the dielectric is formed by the PCB material, air, and liquid. In contrast, the inner coplanar layer doesn’t have to contact the liquid directly.

What is the reduction factor of a capacitive sensor?

Objects being detected that are not metal will have a reduction factor based on the dielectric constant of that object material. This reduction factor must be measured to determine the actual sensing distance however there are some tables that will provide an approximation of the reduction factor.

Can a capacitance sensor be made calculable?

Capacitance sensor is a very precise sensor even in the sub-nm range that can be even made calculable, so we can directly determine the displacement from the actual capacitance and geometrical parameters of the sensor. I. Sherrington, in Tribology and Dynamics of Engine and Powertrain, 2010

How is a capacitive sensor different from an inductive sensor?

Unlike an inductive sensor that produces an electromagnetic field a capacitive sensor produces an electrostatic field. The external capacitance between the target and the internal sensor plate forms a part of the feedback capacitance in the oscillator circuit.