Eddy current testing probe composed of planar coils

This paper presents a new eddy-current probe composed of a micro-planar mesh coil and meander coil. The probe can be used to detect the existence and the size of cracks in metallic structures. Experimental results for the sensed output voltage of this device are presented. The output signal is shown to have a discrete nature. Also, the results show that the signal strength is weak and that an offset voltage exists. Improved probe characteristics are obtained by connecting two mesh coils in series, stacking the coils on top of each other and orienting the two coils 180° apart