Model-based Calibration of a Magnetic Induction Spectroscopy System for Absolute Conductivity Measurement

Magnetic induction spectroscopy (MIS) is a measurement technique where the impedance spectra of an object can be determined by inducing eddy-currents in that object, then detecting the resultant magnetic field. It is an entirely non-contact method, but suffers the drawback of only being able to return relative impedance contingent on the shape of the test object, rather than independent and physically meaningful absolute measurements.In this paper, we address this shortfall by demonstrating a simulation-derived procedure to obtain true conductivities from MIS measurements. We determine calibration constants by using saline solutions of different sizes and conductivities and find an approximate accuracy of +/- 65 mS/m. We further employ this procedure to find approximate absolute conductivities of a baking potato, braeburn apple and conference pear over part of their beta-dispersion region between 100 kHz and 10 MHz.