Planar coil eddy current sensor based on fractal self-similar structure

The invention relates to a novel eddy current sensor structure device used for detecting micro crack defects of metal members. A Koch snowflake graphic scheme in the fractal theory is adopted, and an exciting coil structure of the eddy current sensor is designed by means of a copying method of a self-similar structure, so as to perfect the eddy current distribution density in an eddy current exciting field of a test specimen, improve the sensitivity of micro cracks in the test specimen on the eddy current field and provide a novel structure and a scheme of using the eddy current sensor to perform nondestructive testing on the micro cracks. The invention provides a thought of using a fractal geometrical figure as the exciting coil of the eddy current sensor, the exciting part of the eddy current sensor is designed according to the self similarity of the figures in the fractal theory, and the exciting part forms a planar sensor with the receiving coil of an Archimedean spiral structure. When alternating current is introduced, relatively uniform eddy current with certain strength and different curvatures can be sensed on the surface of a conductor, and cracks with different scales can generate stronger disturbance to the eddy current so as to sense micro defect information in a detecting coil or element.