A Novel Dual Modality Sensor With Sensitivities to Permittivity, Conductivity, and Permeability

Abstract

-In this paper, an electromagnetic (EM) sensor which can operate simultaneously in capacitive and inductive modalities with sensitivities to permittivity, conductivity and permeability is developed, and a novel measurement strategy is proposed accordingly. The sensor is composed of two planar spiral coils with a track width of 4 mm, which promotes its capacitive mode. The capacitive coupling is measured in common mode while the inductive coupling is measured in differential mode. In capacitive mode, the sensor is sensitive to changes in permittivity, i.e. the dielectric material distribution; while in inductive mode, it is sensitive to magnetically permeable material and electrically conductive material. Furthermore, it is demonstrated that the sensor can simultaneously measure dielectric and conductive materials. This novel sensing element has been designed and implemented. Experimental results verified its effectiveness in dual modality measurement.

Three-Dimensional Electromagnetic Mixing Models for Dual-Phase Steel Microstructures

“…e and o represent the edge and vertex number of the whole mesh, respectively. For the austenite-ferrite alloy case, as shown in Equations (6) and 7, the L and N should be empty matrices.…”

“…When considering the effective electrical or magnetic property of a material, which has two components with contrasting properties, a finite element microstructure model can be used to predict the relative permeability [4][5][6] based on actual microstructures. The microstructural phases were considered as constituents with different relative permeability values.…”

Eddy Current Measurement for Planar Structures

“…The planar coil fabricated by flexible printed circuit (FPC) and printing electronic technology (PET) elevates the detection capability of micro-surface defects [116,117]. Furthermore, by employing a suitable track width of the planar spiral coils, the coil impedance consists of both the capacitance and inductance, reflecting various electromagnetic properties simultaneously [118]. To measure the defects in an arbitrary direction, it is efficient to employ a rotating magnetic field probe composed of several Tx coils with different excitation signal phase and positions [104,[119][120][121][122].…”

Experimental Study of Microstructures in Bias Weld of Coiled Tubing Steel Strip With Multi-Frequency Eddy Current Testing

“…Yin et al [15]- [21] and Lu et al [15]- [21] carried out a joint study on the determination of the magnetic permeability and electrical conductivity of ferrite metal plates by multifrequency electromagnetic sensor, and proposed a method to invert arbitrary permeability, conductivity, thickness and emission distance based on multi-frequency electromagnetic sensors. At the same time, Zhou et al [22] studied the effect of sensor lift on the electromagnetic properties of the steel plate and proposed a new method of magnetic permeability measurement.…”