A capacitive liquid level sensor with four electrodes

This paper presents a capacitive liquid level sensor with four electrodes. By detecting the level changes of liquid filled in a cylindrical vessel, not only liquid level information can be measured unrelated to gradient of the vessel, but also gradient status of the vessel can be evaluated at the same time. For this purpose, a new sensor with four electrodes sticked on inside wall of the cylindrical vessel has been designed and a novel measurement method different from conventional one is developed. Experimental results prove that this sensor can be used to detect the liquid level information and the gradient status of the vessel such as it is vertical or gradient, moreover, detailed gradient direction and gradient angle of the vessel on the gradient direction can be estimated if the vessel is gradient.