Detection and Characterisation of Conductive Objects Using Electromagnetic Induction and a Fluxgate Magnetometer

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 16; p. 5934
• Main Authors: Elson, Lucy, Meraki, Adil, Rushton, Lucas M, Pyragius, Tadas, Jensen, Kasper
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.08.2022; MDPI
• Subjects: conductivity; eddy current; Eddy currents; Electric contacts; Electric properties; Electrical conductivity; Electrical resistivity; Electromagnetic induction; Electromagnetism; Field programmable gate arrays; Fluxgate magnetometers; magnetic field; Magnetic fields; Magnetic permeability; Material properties; non-destructive testing; Numerical analysis; numerical simulation; Permeability; electromagnetic induction; magnetic field; magnetic permeability; conductivity; fluxgate magnetometer; eddy current; non-destructive testing; numerical simulation
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22165934

Eddy currents induced in electrically conductive objects can be used to locate metallic objects as well as to assess the properties of materials non-destructively without physical contact. This technique is useful for material identification, such as measuring conductivity and for discriminating whether a sample is magnetic or non-magnetic. In this study, we carried out experiments and numerical simulations for the evaluation of conductive objects. We investigated the frequency dependence of the secondary magnetic field generated by induced eddy currents when a conductive object is placed in a primary oscillating magnetic field. According to electromagnetic theory, conductive objects have different responses at different frequencies. Using a table-top setup consisting of a fluxgate magnetometer and a primary coil generating a magnetic field with frequency up to 1 kHz, we were able to detect aluminium and steel cylinders using the principle of electromagnetic induction. The experimental results were compared to numerical simulations, with good overall agreement. This technique enables the identification and characterisation of objects using their electrical conductivity and magnetic permeability.