Measurement of electrical conductivity for metal wires using an electromagnetic sensor


In this paper, a strategy for non-contact measurement of the conductivity of metal wires used in wire based additive manufacture is proposed. A cylindrical magnetic sensor consisting of coil pair (transmitting and receiving coils) is designed and the change in the mutual impedance due to the presence of the wire inside the sensor is measured at multiple frequencies. It was found that the phase of the impedance (calculated from real/imaginary parts) is linearly related to the conductivity of the wire measured via a contact four-terminal measurement method. This technique can be potentially applied to the real-time and in-situ inspection of metal wires by measuring their conductivity variation, which could help in the quality control of wire based additive manufacture processes.