The paper reports a capacitive sensor for measuring liquid level which was fully fabricated with the inkjet printing technology. The liquid level measurement based on capacitive sensing is already well known technique. The novelty of presented capacitive sensor is used technology, obtained structure flexibility and its dimension. The sensor structure was printed on a thin Kapton substrate with dimensions of 210 mm × 12 mm, and the thickness approximately 27 μm. The sensor was tested on a vessel witch was filled and emptied with water. The tests shown sensor linearity in liquid level sensing and the lack of hysteresis. Obtained sensitivity of the prototype sensor was approximately 74·10-3 pF/mm. The sensor structure can be applied to any shape of vessel. Furthermore, its construction is very simple and in mass production costs could be extremely low. This type of sensor was designed especially for autonomous cleaning and washing machines for large areas.
Paczesnya, D., Tarapata, G., Michał, M., & Jachowicz, R. (2015). The capacitive sensor for liquid level measurement made with ink-jet printing technology. In Procedia Engineering (Vol. 120, pp. 731–735). Elsevier Ltd. https://doi.org/10.1016/j.proeng.2015.08.776