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This paper reports on Giant‐Magneto Resistance (GMR) electronic second order gradiometer used as an EC probe to detect defects in Al‐Ti riveted multi‐layers non‐magnetic metallic samples used in aircraft structures. An electronic characterization of the GMR gradiometer set‐up for investigating the probe performance and its magnetic field sensitivity is presented. The comparison between magnetic images obtained by GMR probes and conventional excitation coils demonstrates the possibility to use successfully GMR technology as sensors for NDT applications.

We explored the modification of polymeric film conductivity by changing the conducting filler percentage in the frame of the percolation theory. The polymeric film is a polystyrene (PS) matrix, while the fillers are gold nanoparticles capped with 1‐dodecanethiol (Au‐DT NPs) and small conjugated molecules 8‐ hydroxyquinoline (8HQ). Experimental results show, that increasing the Au‐ DT and 8HQ wt%, film conductivity increases by up to three orders of magnitude due to charge transfer in the 3D network composed by Au‐ DT NPs and 8HQ.