The development of displacement eddy current sensor independent of sample electromagnetic properties

The displacement between the coil of eddy current sensor and the sample can influence the distribution of the eddy current in sample, consequently cause the change of the coil impedance, so the eddy current can be developed as a displacement measurement device. This paper aims to develop a new of eddy current sensor which is independent of the sample electromagnetic properties. Extended from the theoretical analysis and experiment study for the relationship of the coil resistance and inductance, a new eddy current displacement measurement circuit is presented. Then, the validation for the developed displacement eddy current sensor is performed by a series of experiments. The experiment result indicates that the new eddy current displacement sensor can eliminate effectively the measurement error due to the change of the sample electromagnetic properties.