Continuous monitoring of conductivity using a uniform magnetic field

Abstract

A spherical coil was used to measure a broad range of conductivities of solutions of NaCl in water. The method proposed in this paperrelates the conductivity of the sample with the frequency at the minimum value of an imaginary admittance spectrum when the coil is immersed in the solution. There is a high correlation between the experimental results and the fit equation (r = 0.95). Since the proposed method is an inductive one, the drawbacks of electrode methods are avoided, e.g. the interface polarization impedance. The method presented is fast, does not require an estimate for the Q factor and the measurements do not depend on the sample volume when the coil is completely immersed. This system is capable of continuous monitoring of biological and inorganic samples.