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Design and Potential Analysis of an Eddy Current Sensor for Inductive Conductivity Measurement in Fluids
Julius Harms * , Thorsten Alexander Kern
1  Institute for Mechatronics in Mechanics, Hamburg University of Technology, 21073 Hamburg, Germany

Published: 19 May 2021 by MDPI in 8th International Symposium on Sensor Science session Physical Sensors
10.3390/I3S2021Dresden-10160 (registering DOI)

In the scope of this paper, a first exemplary eddy current sensor for seawater conductivity measurement is developed, based on the derived sensor theory of a previous work. By a high frequency excitation, eddy currents are induced in the fluid and counter-fields measured with a sensing coil. The coils resonance point is used for amplification. The developed prototype is analyzed based on a derived transfer function and FEM-Simulations. The theory is validated using a prototype implementation. With conducted experiments on a sensor test bench, the characteristic were confirmed and disturbances identified. It is shown that frequencies exist, where temperature influence is minimal. This work gives a perspective for a novel sensor to allow seawater conductivity measurement.

Keywords: salinity; conductivity; inductive; eddy current; sensor; low-cost; uncertainty