We report on a highly sensitive plasmon-based nanosensor. This hybrid sensor is composed of a glass tip
with a set of gold nanoparticles grafted at its apex. It allows to optimize the excitation and detection
of the localized surface plasmon resonance of metal nanoparticles and thus to increase dramatically the
sensitivity. First results show the possibility to detect a concentration as low as 10<sup>-10</sup> M on a single gold
dimer. Furthermore, promising SERS measurements are reported.