Résumé
The main way to increase the spatial selectivity hasbeen to make coils with smaller and smaller diameters. Thisis especially true for secure applications (side-channel attacks).In this paper, we investigate an alternative way with secureapplications in mind. It consists in designing probes that measurethe derivative of the magnetic flux instead of the flux itself.The paper presents the motivation, the concept and preliminaryresults obtained with a first prototype.