We report a strategy to address stem-loop oligonucleotides on a gold surface in order to develop a robust and ultra-sensitive integrated electrochemical DNA sensor. Probe immobilization relies on the potential-assisted copper-catalyzed alkyne-azide cycloaddition. Firstly, a tetrathiol-hexynyl derivative was used to introduce alkyne functions onto the electrode surface. This anchor has proved its robustness in conditions used for the " click " reaction and in wet storage. Then, different ferrocenyl and azido-modified stem-loop oligonucleotides were synthesized using the solid-phase synthesis technique and their immobilization was studied. Hybridization assays with the DNA target were performed in a complex medium by cyclic voltammetry. The detection sensitivity achieved by our functionalized electrodes was significantly increased, as a detection limit of 10 fM was determined. We also demonstrated that grafting of the stem-loop oligonucleotides via the electroactivated " click " reaction was specific to the gold surface on a microfabricated electro chemical device for the Lab-on-Chip application that fully integrates Au working microelectrodes, Pt counter and Ag reference electrodes. ã