A device for forming waves at the interface (I) of a liquid drop (F1) by electrowetting, enabling the micro-mixing and concentration of constituents at the interface (I) of the drop (F1). The device comprises at least one excitation electrode suitable for generating an oscillating and radial electric field about a first axis of symmetry, under the effect of an electric control, and a liquid drop (F1) arranged on said excitation electrode and having an axis of symmetry coinciding substantially with said first axis of symmetry, such that said electric field generates essentially axisymmetric waves at the interface (I) of said drop (F1).