The invention relates to a miniature
eddy current sensor with a structure consisting of a
silicon substrate and multilayer coils, and belongs to the field of miniature sensors. The miniature
eddy current sensor is used for detecting micro-cracks on surfaces of
metal components, is based on the three-inch
silicon substrate with the thickness of 200 micrometers and comprises a single-layer
excitation coil, multiple
layers of detection coils, conducting
layers and insulating
layers, each two layers of detection coils are serially connected and communicated by a central lead in a reverse spiral surrounding manner, flow directions of induced currents of the detection coils are consistent assuredly, and detection signals are intensified; and each silica insulating layer is filled between the corresponding detection coil and the
excitation coil. The size of the section of each detection coil can be 10 micrometers X 10 micrometers, 20 micrometers X 15 micrometers and 30 micrometers X 15 micrometers, each coil includes 10 turns, the corresponding size of the section of the
excitation coil can be 140 micrometers X 20 micrometers, 290 micrometers X 20 micrometers and 430 micrometers X 20 micrometers, and the excitation coil includes a single turn. The
inductance coils are squarely or circularly spiral in a planar manner, and are distributed in a matrix manner according to the shapes and the sizes of the
inductance coils, so that detection area is increased, and detection efficiency is improved. By the aid of via UV-
LIGA (
ultraviolet-
lithography) which is precision
processing technology on the basis of a micro-electro-
mechanical system MEMS, the miniature
eddy current sensor has the advantages of slim structure,
miniaturization and high sensitivity and efficiency, and is applicable to nondestructive detection of microdefects on surfaces of
metal workpieces.