Magneto-inductive conductivity sensor

Abstract

Multi-element inductive coil systems are used to measure locally resolved conductivity profile. Usually such sensors rely on the separate interrogation of each coil. In addition, the coils must generally be magnetically decoupled for accurate signal processing. Here we demonstrate a metamaterial conductivity sensor that uses broadband interrogation of a line of coupled resonators. No decoupling is needed, which allows a transmission measurement to be carried out. The resonant elements of the metamaterial are coupled with each other and their neighbourhood which affects their quality factor. We derive analytically an algorithm to extract the local perturbation in each element from the modal measurement. We investigate numerically the performance of the sensor and derive an optimal configuration in terms of nearest neighbour coupling and the initial non-uniformity. Finally we implement a four-element magneto inductive conductivity sensor and show that a conductive perturbation along the line can be accurately reconstructed. Generalisation to higher number of elements is also discussed.