Smart elastomer based liquid level sensors with capacitive and resistive measurement principles (Conference Presentation)

Different capacitive and resistive elastomer sensors for the measurement of the filling level of water in a vertical tube are introduced. The filling level sensors consist of elastomer membranes carrying conductive layers with special geometrical designs. Three different basic sensor principles in various versions were investigated. First, resistive strain sensors detect the pressure of the water column above the elastomer membrane by measuring the change of electrical resistance due to a stretch deformation. Second, capacitive strain sensors with different electrode designs and materials are also stretched by the water pressure acting on the membrane and change the capacitance. Third, capacitive proximity sensors detect the height of the water level by measuring the capacitance between two neighbored electrode layers on the membrane. The advantages and disadvantages of the different sensor principles are discussed.